CA1097345A - Intermediates for polycyclic quinonoid antibiotics - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

There is provided a novel tetracyclic quinones par-ticularly 7,10-dihydro-1,6,11 and 4,6,11-trihydroxy-5,9,12(8H)-naphthacenetrione and the 1- and 4-ethers thereof which are useful as intermediates in the synthesis of (?)-7-deoxydauno-mycinone and analogs thereof. The 7-deoxydaunomycinone derived from naturally occurring daunomycin is a known compound, which is itself an intermediate in the preparation of the clinically accepted anti-tumor antibiotics daunomycine and its derivative adriamycin.

Description

RELATED APPLICAI'IONS
., ,, _ NoneO

BACKGROUND OF THE INVENTION

Adriamycin, an antibiotic compound which is use-full in the treatment of certain tumors is described and claimed in U. S. Patent No. 3,590,028, to Arcamone, et al.
A further procedure for the preparation of adriamycin will be found in U.~ S. Patent No. 3,803,124 to Arcamone, et al. Said patent also disclose~ that the adriamycin may be prepaxed from daunomycinè or its aglycone dauno-mycinone.

;, . ' A total synthesis of daunomycinone has been disclosed by Wong, et al, ~Canad. J. Chem., 51, 446 ~1973)).
This synthesis, while apparently operative, gives such small yields that its use as a commercially viable alter-native to the fermentation derivation of daunomycin and ~ ~
.

I adriamycin is not considered feasible.
.

A further approach to the synthesis of (+)-9-deoxydaunomycinone, another intermediate in the synthesis of daunomycin, is disclosed by the Applicant herein and co-workers in J. Amer~Chem.5Oc., 97, 4425 (1975~. This ap-proach is quite different ~rom the approach to the synthesis of daunomycinone to be described and claimed herein.
"'' , ' . . . .

3719 (30~
. . .

It should also be noted that the couplir.q of daunomycinone with the appropriate sugar to yield aauno-mycin (also known as daunorubicin) is found in Acton, et al., J.Med.Chem., 17, 659, (1974). The sugar, dauno-samine utilized in the Acton synthesis of daunomycinone is disclosed in Marsh, et al, Chem. Commun., 973, (1967).

DESCRIPTION OF THE PRIOR ART
The first novel compound in the synthetic sequence to be disclosed and claimed herein is the ether of ~-hydroxy-quinizarinquinone, in particular, the lower alkyl, especially the methyl ether thereof. The immediate precursor in the present synthesis is 1,4,5-trimethoxy-9, 10-anthraquinone which is described in several publica-tions, for example, Wiles and Thomas, J.Chem.Soc., 4811 ~1956). The 5-hydroxy-1,4,9,10-anthradiquinone is also known. (Dimroth and Hilcken, Ber., 54, 3050 (1921)).
While it might be thought, that the 5-hydroxy anthradi-quinone is a suitable starting material for the cor,es-ponding ether, that is, in fact, not the case. It is ) taught by Wiles and by Dimroth that the conditions which would be required to alkylate, in particular,methylate a hydrogen bonded phenol of this type would be so vigorous as to destroy the desired product. It should be noted in this connection that the 5-methoxy ether decomposes above 85C or in the presence of a strong base, and thus would not be readily accessible by the O-alkylation, suitably methylation of the corresponding phenol.

The oxidative dealkylation of the triether of 1,4,5-trihydroxy-9,10-anthraquinone to the corresponding ,. _ .

~ 73~;

monoe~her of 5-hydroxy-1,4,9,10-anthradiquinone is ac-complished by the method of Snyder and Rappaport, J.Amer.
Chem.Soc., 94, 227 (197~).

A Diels-Alder reaction of a type related to, but distinguishable from, the conversion of the quini-zarinquinone (III) in the principal reaction sequence to the corresponding naphthacenetetraone SIV) is disclosed in Inhoffen, et al, Ber. 90, 1448 (1957). The present reaction can be distinguished therefrom in that the reaction of the reference i5 concerned with esters and ethers of l-hydroxy-1,3-butadiene and the present reaction sequence is concerned with esters of 2-hydroxy-1,3-butadiene While this difference may appear, at first gla~;ce, to be minor, it should be noted that the reference is concerned not only with addition at the 2 and 3 posi-tions but also at the 4a and 9a positions of the quini-zarinquinone nucleus. The provision of the good yields obtained in the present process by addition across the

2 and 3 positions cannot be considered to be a foregone conclusion and is highly dependent on the substituent(s~

in the diene component. Thus, 2-ethoxy-1,3-butadiene in our hands adds mainly to the undesired 4a,9a ~ouble bond, as do certain Examples cited by Inhoffen.

SU~ARY OF THE INVENTION

There is provided a novel process for the pre-paration of c~rtain polycyclic quinones and polyquinones, in particular, there is provided a method of synthesizing daunomycinone ana analogs thereof.

~1(2i) 3 78 _ _ )~7)

3~5 The general reaction scheme is set forth herein below. It should be noted that compound ~ wherein R1 equals R2 equals R3 equals methyl is a known compound.
Similarly, compound II wherein Rl equals R2 equals R3 equals methyl or H are known compounds.

+ ~ ~ ~ ~ ~ Il 2CR4 ~ ~ 02C.R4 III ~ 3 ~ ~ IV

OH O OH

R1 ~ ~ ~ ~ VI
O OH O OH
V

~ QH O QH OH
~~_ I I 11 1 1 ~ I I I
~ ~ ~f ~

~
o ~ ~w x IX

~ ~ "OH ~ DAUNOMYCIN

3700t8) r n R10 O OH d ~ XI

- 4 -~ s will be seen ~rom the attached flow chart, suitable starting materials for the process of the present invention may be trihydxoxy compounds of formula (II) where it is desired to produce the 4-0-demethyl analog of (+)-7-deoxydaunomycinone, otherwise known as (+)-7-deoxy-carminomycinone,which is an`intermediate for the biologi-cally active Carminomycin-I described inter lia (M. Wani, et al, J. Am. Chem. Soc, 97, 5955 (1975)). Similarly, if this compound is the desired end compound, compound (II) may be the triester. Since the trihydroxy compound is readily available, ~see for example, U.S.-Patent No.
1,963,136 to Kirk, et al), there appears to be little point in synthesizing the triester.

Where it is desired to provide a compound of general formula (IX) wherein the group at position 4 is an ether, then it is desirable to commence the reaction with a compound of general formula (II) wherein formula (II) is a triether. Triethers of general formula (II) may be readily prepared by a Friedel-Cxafts reaction between the appropriate phthalic anhydride and the corres~
ponding diether of hydroquinone. The resulting bicyclic acid (I) is then ring closed by means of a cyclodehydrating a~e~lt, suitably concentrated sulfuric acid, anhydrous hy-drogen fluoride or polyphosphoric acid, to yield the de-sired triether (II).

Compound (II) is then oxidized to yield the corresponding substituted quinizarinquinone (III). Where compound ~II) is a triether, th~ compound (III) will be the 5-ether of quinizarinquinone. In this case, it is pxeferred to use as oxidant silver (II) oxide in a suit-able water-miscible organic solvent in th~ presence of !5 ~2~8) '34~
mineral acid. Where c~mpound (II) has R2 = R3 = H, oxidation may be carried out by hea~y metal oxidants including ceric ammoni.um nitrate or by lead tetraacetate in acetic acid. ~her~ it is desired to form compounds leading to carminomyc-n where there is a hydroxy group at the 5 position, 5-hydroxyquinizarinquinone is prepared ~y methods known to the art and utilized as the starting material at this stage.

The quinizarinquinone compound (III) is then subjected to a Diels-Alder reaction with an ester of 2-hydroxy-1,3-butadiene to yield the mixture of regioisomers namely, the 1- and 4-ethers or esters of 7,10-dihydro-1,9-and 4,9-dihydroxy-5,6,11,12-naphthacenetetraone 9-ester (IV).

Similar].y, when compound (III) is the 5-hy-droxyquinizarinquinone rather than the ether thereof, com-pound (IV) consists of the corresponding mixture of the 1- and 4-phenolic 9-esters.

The mixture of regioisomers of compound (IV) are then r~acted with a proton acceptor or proton donor in a suitable solvent to yield the corresponding 7,10-dihydro-1,6,9,11 and -4,6,9,11-tetrahydroxy-5,12-naphthacenedione 9-ester and the corresponding 1- and 4-ethers thereof (compounds Y).

The 9-ester is then cleaved, suita~ly by mineral acid in a water-miscible organic solvent such as ethanol, aqu~ous acetic acid or tetrahydrofuran to yield 7,10-di-hydro-1,6,11- and 4,6,11-trihydroxy-5,9,12(8H)-naphtha-cenetrione and the 1- and 4-ethers thereof (compounds VI).

!~8) -6-a5 Mild base is also operative but not as efficient. The direct conversion of Diels-Alder a2ducts IV to compounds (VI) with strong acid in a water-miscible organic solvent -is a feasible alternative to the two step sequence outlined above and proceeds in comparable yield.

Compound (VII) is then converted to the corres-ponding 9-ethynylcarbinol by reaction with an alXali metal acetylide or an ethynyl Gxignard reagent to yield the 4-. ether of 9-eLhynyl-7,10~dihydro-4,6,9,11-tetrahydroxy-5,12 ~8H~-naphthacenedione (VIII). The ethynyl moiety of com-pound (VIII) is hydrated to yield the 4-ether of 9-acetyl-7,10-dihydro-4,6,9,11-tetrahydro~y-5,12(8H)-naphthacene-dione (IX). Where the 4-ether is the methyl ether~ com-po~nd (IX) is (-~)-7-deoxydaunomycinone, and where, in place of an ether group at the 4 position, there is a hydroxy group compound (IX) is (~)-7-deoxycar~,inomycinone.

Both deoxydaunomycinone and deoxycarminomycinone may be converted into the corresponding 7-hyuroxylated compound and thence ~o daunomycin and carminomycin by various methods. The introduction of the 7-hydroxyl may be accomplished by a novel variant of benzylic bromination followed by solvolysis. The subsequent glycosidation at the C-7 hydroxyl is achieved in the man~er set forth hereinabove by Acton, et al .

3592(~) ~56~

~73~L~

DESCRIPTION OF THE PREFERRE:D EMBoDIMENTs . _ Preparation of Starting Materials The starting materials of the process of the present invention may be considered the compounds of formula (III) hereinabove. The 4-hydroxyquinizarinqui-none of this general formula is a known compound and may be pxepared either by the method of Dimroth and Hilcken (ser., 54, 3050 (1921), or Kirk, et al, (U.S. Patent No.
1,963,136). Where compound (III) is a 4-ether it is to be considered a novel compound and may-be prepared by generally known methods from the appropriate ether of 3-hydroxyphthalic anhydride. In this procedure, there may be employed any appropriate ether, for example, the ether group may be alkyl, suitably lower alXyl, for example, methyl, ethyl, propyl, butyl, or pentyl. The ether may also be an aralkyl ether such as a phenyl-alkyl or substituted phenyl-alkyl ether, suitably where the ~lkyl is a lower alkyl, for example, wherein lower alkyl is as listed above and the substituents of which there may be be-tween 1 and 5, and may be alkyl, suitably lower alkyl, such as those listed above, or alkoxy, suitably lower alkoxy such as the oxy derivatives of the lower alkyl moieties listed above, or halo, for example, fluoro, chloro, bromo or iodo.
E'urthermore, hereinabove and hereinbelow the prefix "lower alk" shall be considered as designating a saturated carbon skeleton bearing hydrogen atoms on said skeleton in all positions except where said skeleton is ~onded to another group and containing 1-5 carbon atoms Where compound III is a 4-ester, it can be pre-pared from the appropriate ester of 3-hydroxyphthalic an-hydride in the same manner as the 4-ether.
g(29) - 8 -~9~3~5;
~he phthalic anhydride is then subjected to a Friedel-Crafts reaction with hydroquinone, hydroquinone diether or hydroquinone diester. The ether groups utilized may be the same as each other or different from each other and may be the same as or different from the ether moiety on the 3-position of the phthalic anhydride with which it is to be reacted. Since however in a subsequent stage of this reaction, said ether groups are to be oxidati~ely removed to form a quinone moiety, it is preferred to utilize any readily available ether in this category of which p-dimethoxybenzene is preferred.
In carrying out the Priedel-Crafts reaction, the 3-hy-- droxyphthalic anhydride or its derivatives is taken up in a dry reaction inert organic solvent to form a solu.ion or suspension therein. The solvent utilized should of course be non-hydrox~lic; solvents such as methylene chloride, nitrobenzene or carbon disulfide are considered suitable. To the mixture is added an excess, suitably about a 100% excess of anhydrous alumlnum chloride.
There is no specific temperature limitation upon the ; reaction, however, the reaction is rather slow at temperatures below O~C, and proceeds too rapidly at - elevated temperatures r thus it has been found advantageous ts carry out the reaction at ambient temperatures, that is to say, at temperatures between about 10 and abou~
30C, suitably about 20C. To this solution is added the hydroquinone derivative in a similar solvent. Thexe is utilized an excess of said hydroquinone derivative, suitably a 100~ excess relative to the anhydride. The xeaction mixture is stirred vigorously and after completion of the addition agitation is continued at ambient tempera-ture for from about 12 to 36 hours.

8~g130 027(25) 9 :~97;~5 The reaction is then quenched by pouring it onto a mixture of ice and concen~rated hydrochloric acid. The slurry is agitated vigorously and then ex-tracted with a water immiscible polar organic solvent, suitably a halogenated hydrocarbon solvent such as chloroform. Other organic solvents, for example, hy-drocarbon solvents such as benzene, may be empl~yed but are not preferred. During this extraction some of the desired ketoacid may precipitate and is colledted by filtration.

The organic extract is washed with water, ex-tracted with mild aqueous base, suitably saturated alkali metal carbonate or bicarbonate, such as sodium carbonate or bicarbonate, and said aqueous basic extract after washing with a fresh sample of the organic solvent used in the previous step, is acidified, suitably with a mineral acid, preferably with concentrated hydrochloric acid, cooled, suitably to between -5 and ~5C and the precipitate thereby formed is separated, preferably by ~0 filtration. There is thus obtained a product o~ g~neral formula (I) in the foregoing flow chart which, except for the desired st~p of drying same to remove the moisture therefrom, is of sufficient purity for use in the next step of the reaction.

Compound ~I) is then converted to the corres-ponding anthraquinone (II) by reaction with a cyclodehy drating agent. Any reagent which will thus dehydrate an O-benzoylbenzoic acid may be utilized. Am~ng these reagents may be listed phosphorus pentoxide, polyphos-phoric ~cid, anhydrous hydrogen fluoride and concentratedsulphuric acid; of these concentrated sulphuric acid is 27(26) 15 (19) ~ 739~

to be preferred. Compound ~I) is added portionwise to a substantial excess of agita~ed concentrated sulpnuric acid. After aadition is complete the mixture is heated to moderately elevated temperatures suitably from about 70 to about 9CC, with constant agitation, for from about 15 to about 40, suitably from about 20 minutes.
The now blue-colol-ed mixture is cooled to ambient tempera-ture and then the reaction is quenched by pouring onto crushed ice. The aqueous mixture is then extracted with a water immiscible organic solvent, preferably a polar organic solvent, suitably a halosenated hydrocarbon sol-vent, preferably chloroform, and the organic extract washed with dilute aqueous alkali, and then water, fol-lowing which the extract is dried and the solvent re-moved to yield the desired product ~II). It is preferred to further purify compound (II) and such purification may be achieved by recrystallization, suitably from a lswer alkanol, such as ethanol or 2-butanol.

Compound (II) is then oxidized to Compound (III3.
In the case of triether, Compound (II) is taken up in a reaction inert, water-miscible organic solvent. In view of the fact that the present step involves oxidation, said solvent should be relatively inert to oxidation.
It has been found that ketones, suitably dialkyl Xetones, pref~rably acetone, may be utilized. It i~ further pre-ferred that the solvent be heated to a temperature at or near its boiling point.

To the warm solution is added a substantial excess of the oxidizing agent. It is preferred to utilize between 2 to ~ moles, suitably about 3 to about 5 moles

5(20~
~(18) ~73~

of oxidizing agent per mole o~ compound (II). It has been found advisable to briefly sonicate the mixture to obtain uniform dispersal of the oxidant. Among the oxidizing agents which may be used silver (II) oxide (argentic oxide) is especially preferred. The mixture is then heated, suitably under reflux, and vigorously agitated The reaction is then initiated by the addi-tion of a small amount of acid, suitably mineral acid, preferably concentrated nitric acid. The reaction is rapid and should be considered complete in 10-30 minutes.

The acid utilized should be a strong acid, however, the quantity thereof is more critical than its nature. The amount of acid utilized should be just suf-ficient to dissolve all of the silver oxide. If an amoun$ substantially greater than this is employed, the water present in the acid will interfere with the reaction and lower the yields obtained. The reaction mixture is then filtered, and the residue washed thoroughly with 2 water and dried under reduced pressure to yield the ap-propriate 4-ether compound (III~ in sufficient purity to take part in the next stage of the reaction.

Wh~re Compound ~II) carries ester groups in the 1 and 4 position (i.e. R2 and R3 are acyl as defined) tne compound is cleaved to yield the free hydroquinone analog.

Where compound (II) has a hydroquinone structure (R2 = R3 = H) oxidation to III is preferably accomplished using lead ~etraacetate in acetic acid.

I ~19) ~12~

The 4-hydroxyquinizarinquinone or 4-ether thereof (Compound III) is taken up in an organic sol-vent, preferably in the presence o~ an organic acid and subjected to a Di~ls Alder condensation with 2-hydroxy-1,3-butadiene 2-ester. Since the ester group at the 2 position of the butadiene will be removed in the next but one stage of the reaction sequence, the nature thereof is in no way critical. Any fairly readily hydrolyzable ester group may be employed. These include alkanoates, suitably lower alkanoates such as acetate, propionate, butyrate, valerate, and the like, aroyl esters for example benzoate and naphthoate, and their nuclearly substituted derivati~es, aralkanoates, suitably aryl lower alkanoates, such as phenyl lower alkanoates, suitably benzylacetate, benzylpropionate, benzylbutyrate, and the like. Among these groups the acetate and the benzoate are to be preferred merely for reasons of ready accessibility and cost.

The reaction may be carried out in polar or nonpolar solvents, hydrocarbon solvents, suitably aromatic hydrocarbon solvents such as xylene or toluene may be employed, similarly halogenated hydrocarbons such as chloroform or methylene chloride may be l~sed, equally mixtures of b~th of these groups of solvents may be em-ployed. To improve the yield of the desired adduct it has been found advantageous to employ an organic acid as solvent or cosolvent. It has been found that lower alkan-oic acids suitably acetic acicl are to be preferred. It has been found suitable tG prepare a solution of between 5 and 15~ by weight of the reac~ants in a solvent mixture of the inert solvent and the acid~ A mixture of 1 part 3(~3~
~(11) -13-73~5 of solvent to 2 parts (by volume) of the acid have been found suitable, although pure acetic acid is also satis factory. In order to maximize the yield of desired pro-duct, that is to say, a compound wherein the addition takes place as shown in ccmpound IV, rather than at the 4a and 9a positions, the reaction should be carried out under the mildest conditions concommitant with reasonable reaction rates. Thus, it is preferred to run the reaction at ambient temperature, that is to say, between about 10 and about 40C, suitably about 20C for from about 2 to about 6 days under agitation, at about 20~C the time for completion of the reaction is about 4 days.
The adduct (IV) formed in the xeaction usually separates out as a precipitate and may be removed from the reaction mixture by filtration. rhe adduct may then be purified, suitably by washing with water and drying under reduced pressure.
.

The adduct !IV~ is then enolized to the phenolic tautomer (V). The enolization is achieved by treatment f IV with a proton acceptvr or proton donor in a suitable organic sol~ent. It has been found that salts of alkanoic, aroic or aralkanoic acid, such as acetates~ butyrates, benzo2tes, naphthoates, ~henyl acetates, phenyl propion-ates, ana the like in the presence of the corresponding acid, suitably the same acid as that forming the anion of the salt, may be employed. The preferred conditions include, for example warming the compound in an alkanoic acid solvent containing either an alkali salt of that acid, or mineral acid, or p-toluene sulfonic acid. In the 3~ preferred variant of the r~action, the adduct is dissolved o (4r) ~739!~

in giacial acetic acid at a temperature just below its boiling point, and the proton acceptor, preferably anhy-drous sodium acetate, added thereto. There need only be utilized between 0.1 and 0.3 mg of the proton acceptor per mole of adduct. The enolization takes place very rapidly, but it is desirable to continue heating for 1 or 2 minutes after the addition. The reaction mixture is then ~ooled to ambient temperature, sufficient water added to precipi-tate the enolized adduct which is then separated suitably iO by filtration, washed, and dried under reduced pressure.

She two-step conversion of Diels-Alder adducts (IV) to the corresponding 9-ketones (VI) can be combined into one by warming compounds (IV) with a small amount of strong acid in a water-miscible organic solvent (e.g. lower alcohols), followed by work-up as described above for (VI). This alternative route proceeds in yields similar to the two~step sequence.

The enol ester (V~ is then hydrolyzed to the corresponding 9-ketone (VIj. While the hydrolysis itself 20 is a step which is well known in the art, extreme care must be taken that in the course of this step the presence of oxidizing agents, in particular, air, are held to an ab-solute minimum in order to avoid unwanted aromatizatlon of the saturated alicyclic ring. This aim is suitably achieved by degassing the reaction medium and carrying out the reaction in the presence of a substantially inert gas. For this purpose any of the inert gases or nitrogen may be utilized, nitrogen being preferred for reasons of cost. In the pxeferred procedure, the enol ester (V) is 30 suspended in an alkanol, suitably a lower alkanol, for 3~(41) '7(2~ -15-~7345 example, ethanol, ~che suspension degassed and the con-tainer flushed wi~.~. nitrogen. There is added to the suspension, an eY.cess o mineral acid, preferably 6N
hydrochloric acid, since this acid does not have any oxidizing properties. Degassing and nitrogen flushing procedure is again repeate~, the mixture heated under reflux for from about 4 to about 8 hours, suitably for about 6 hours, cooled to ambient temperature, suitably about 20C, diluted with water and the aqueous mixture extracted with a suitable immiscible organic solvent, preferably halogenated hydrocarbon solvent, such as chloroform. The chloroform extract is washed with water, dried, and the solvent removed to leave a residue which is then purified to yield the desired 9-ketone (VI) which is then purified.

Puriication of the 9-ketone may ke carried out by chromatography. Where small quantities are involv~d, chromatography on silica gel plates and elution with 5~
hexane in chloroform or 3% methanol in methylene chloride has been found operative. It should be noted that the product (VI) is not a single compound but is in fact the reg;oisomeric mixture of the 1- and 4-ethers or phenols as the case may be. In some reactions the 9-Xetone ~reci-pitates directly rom the aqueous-ethanolic reaction mix-ture enriched in the 4-methoxy regioisomer.

These regioisomers may be separated by differential crystallization. It has been fotnd very useful to carry Otlt this crystallization in ethanol. The 4~isomer is 7~28) the less soluble and may be readily separated from the 7~i~

~16-17;34~

l-isomer by treatment with boiling ethanol follo~ed by filtration. It has been found sllfficient to carry out two (2) treat~lents in this manner, in order to re-move the l-isomer from the 4-isomer. Needless to say, there will be a certain loss of 4-isomer in the solution thus removed, however, this may be recovered by crystal-lization techniques well known in the art. Other solvents such as ethyl acetate or isoamyl alcohol may also be em-ployed for the separation but offer no advantage.

While it is preferred to carry out the afore-mentioned resolution of the regioisomers prior to the ethynylation s~ep, the reactions are operative without said step and the resolution may be carried out at ~ later stage. Hence, any statements which are made hereinbelow with respect to the 4-hydroxy compound or the 4-ether are equally appl~cable to the mixture of the corresponding 1-and 4- regioisomers.

It is noteworthy that treatment of the 1- and 4-methyl ethers corresponding to strucutre VI (Rl = C~3~
with anhydrous aluminum chloride in methylene chloride gives a high yield of the corresponding 1- and ~-hydroxy derivatives (VI) ~Rl - ~), providing an alternative route to the latter compounds.
:
The ethynylation of compound (VII) may be carried out by reaction with an ethynyl Grignard reagent. In the preferred approach, acetylene is purified, suitably by passage thru, sequentially, alumina and concentrated sul-phuric acid, and bubbled into a suitable ethereal solvent until said solvent is saturated with a sufficient quantity o* acetylene, but bubbling is continued. Dioxan, tetra-77(1) 77(25~ -17-~73~i hydrofuran or diethylether may be employed, however, freshly distilled tetrahydrofuran under an inert atmos-phere such as an nitrogen atmosphere is preferred. The acetylenic solution is then converted into the corres-ponding Grignard reagent in the usual manner, that is to say, a predetermined quantity of a suitable alkyl Grignard reagent, preferably a lower al]cyl magnesium halide, most suitably ethyl magnesium halide, in an ethereal solution, is added in portions. When all of the said Grignard reagent has been added, the passage of acetylene is stopped and less than equimolar amount of a solution of compound (VI), preferably comprising about 0.01-0.2 moles relative to the Grignard reagent as prepared above, is added in a suitable ethereal solvent, preferably in dry tetrahydrofuran The mixture is then agitated, suitably at ambient temperature, under an inert atmosphere, for from about 12 to about 18 hours. The reaction mixture is then quenched, preferably by the addition or cold saturated ammonium chloride solution, or aqueous oxalic ^~ acid, the organic (ethereal) phase set aside and retained, and the aqueous phase extracted with a suitable nonhy-droxylic, water immiscible, organic solvent, preferably ethyl acetate. The ethyl acetate extract and the ether extr~ct are then combined, dried, and evaporated to dryness to yield the ethynyl carbinol (VIII). This xesidue may be further purified.

The manner of purification is not critical and will depend upon the quantities available. It has been found found that chromatsgraphy on silica, utilizing as an eluent 30 a mixture of an alkanol with an alkylene halide, suitably 3% methanol in methylene chloride may be employed.

(25) (20) ~ 973~

The thus produced ethynyl carbinol (VIII) is then hydrated to form the desired 9-hydroxy-9-acetyl com-pound (IX). Where the substituent in the 4-position is methoxy, this compound will be (+)-7-deoxydaunomycinOne and where the substituent at position 4 is hydroxy, the compound thus produced will be (+)-7-deoxycarminomycinone.

In this procedure the ethynyl carbinol (VIII) is taken up in a reaction-inert polar organic solvent, suit-ably a halogenated hydrocarbon such as chloroform, methylene chloride, or the likeO There is also prepared a fresh solution of mercuric lon, preferably in the presence of a mineral acid. The source of the mercuric ion is not critical, salts of mineral acids such as mercuric sulphate or salts of organic acids, such as mersuric acetate or the yellow mercuric oxide itself, ~ay be employed. It is generally preferred to utilize yellow mercuric oxide in a small amount of watPr contain-ing about 15~ pex volume of concentrated sulphuric acid.
The zcidic solution is warmed to betweè~ 60 and 80~C, the solution of the carbinol added thereto, and the mixture heated, suitably under reflux, for from about 2 to about

6, suitably from about 4 hours, cooled to ambient tempera-ture, quenched in water, and extracted with a suitable solvent, for example, a water immiscible organic solvent such as chloroform or ~he like. The organic extracts are washed, treated with a mild base, suitably saturated sodium bicarbona~e, to remove residual traces of acid, dried and the solvent removed.

38 (10) -19-~97134~;

The residual material, compound ~IX), may be then further purified, suitably by chromatography, pre-ferably on silica gel, to yield the racemic mixture of the desired product.

In an alternative procedure, compounds (VIII) may be eonverted to the 9-acetates or trifluoroacetates of compounds (IX) by stirring with mercuric acetate or trifluoroacetate respectively in an inert polar organic solvent, preferably ethyl acetate. Vnder these reaction cvnditions, certain compounds of type VIII lead directly or in part ~o the free 9-hydroxy compounds (IX), isolated as noted above. Subsequent treatment of the 9-esters by dilute aqueous base yields the free 9-hydroxy compounds (IX), isolated and purified as described above.

As stated above, the compounds of general formula (IX) wherein the 4-substituent is methoxy, namely the (~)-7-deoxydaunomycinone, and where it is hydroxy, namely ( )-7-deoxycarminomycinone, may be converted to the 7-hydroxylated compounds by a sequence proceedin~ through benzylic bromination.

Although similar chemistry utilizing N-bromo-succinimide on related but different substrates has b~en reported by Wong, et al.~ (Canad. J.Chem., 51, 446, ~1~73)), that reagent i5 generally unsat:isfactory when applied to the intermediates of our invention.

Compound (IX~ (either as the mexiture of regio-~omers or the 4-ether or hydroxy isomer) is treated with a free radical source o bromine under conditions which 3~

substantially reduce the accumulation of hydrobromine acid.

Suitably, compound (IX) is taken up in an inert, non-polar organic solvent. sromine, a similar solvent, is added in the presence of a free radical source, suitably a source of ultra violet light. The concentration of hy-drobromic acid is reduced to preclude conditions of ionic bromination, a stream of inert gas, suitably a stream of nitrogen is passed continuously thru the reaction syste~.
Other means of elimination of the acid may also be employed.
Specifically, dry nitrogen is bubbled through a dilute solutïon of (+)~7-deoxydaunomycincne in carbon tetrachloride.
; The solution is irradiated with a sunlamp while a dilute solution of bromine in carbon tetr~chloride is added (in large excess, say from 2-6 fold excess~ over several, say, 1~4 hours, under steady nitrogen bubbling and stirring.
The brominated material is no~ isolated as such but is merely concentrated. The brominated material is then hydrolyzed to replace the bromine at the 7-position with a hydroxyl. The hydrolysis may be one stage or two stage.

In the single stage method, there is used water, mild base, such as aqueous alkali, an a kaline earth metal carbonate, such as sodium carbonate or calcium rar-bonate. Hydrolysis may be achieved in substantially non-aqueous media by passing a solution of the brominated material in an organic solvent over alumina or silica gel.
While the reaction is carried out in a substantially dry environment - since otherwise the alumina on the silica gel would clog, i~ is advisable for either the solvent or, the alumina or the silica gel ~o contain some water, up to 10~ by wei~ht is suitable. Preferably, the residue ~193 ~73~L~

taken up in chloroform, and the chloroform solution run through silica, either in the form of silica gel column or a silica gel plate. Elution with a suitable solvent, for example, 3% methanol in methylene chloride, yields a mixture of daunomycinone, epi 7-epidaunomycinone, and recovered starting materials in an approximate ratio of 2:3:1.5.

In the two-stage hydrolysis, the brominated material is treated with a suitable derivative of an alkanoic acid, an ester or the silYer salt of an alkaline acid may be employed, suitably the silver salt is used.
Most suitably, silver trifluoroacetate is employed. The thus produced 7-trifluoroacetate is readily removed, suitably with mild base to yield the desired 7-hydroxy derivative.

The epidaunomycinone may be readily converted to the desired daunomycinone by acid epimerization. In this procedure the epidaunomycinone is taken up in tri-fluoroacetic acid, allowed to stand at ambient temperature from about 1 to about 3 hours, quenched in water, ex-tracted with a water immiscible polar non-hydroxylic sol-vent, preferably halogenated hydrocarbon solvent, such as chloroform, the solution washed with water, dried~ and chromatographed as set forth above, to yield the desired daunomycinone in approximately 75% yield.

An entirely parallel sequence o~ benzylic bro-mination, solvolysis and acid catalyzed 7-epimerization is carried out with (~)-7-deoxycarminomycinone to give carminomycinone.

2(1g) D~5) _22-~73~i An alternative route to (*)-7-deoxycarminomycinone may be achieved by O-d~methylation of (*)-7-deoxydaunomy-cinone by anhydrous aluminum chloride in an inert organic solvent such as benzene or methylene chloride at tempera-tures of 10-35, preferably 20, for about 16 hours. Under the same conditions, (+)-daunomycinone itself is 0-demethylated to give (+)-carminomycinone in good yiela; the natural (+)-daunomycinone reacts in the same manner to give (+)-carminomycinone. These procedures illustrate that synthetic access to the carminomycinone series is available either by starting with the 5-hydroxy variants of diquinone (III) or by demethylation of t~.e above tetracyclic dauno-mycinone derivatives/ or of the 4-methyl ether (VII) (Rl = CH3).

The synthetic ( ~-7-deoxydaunomycinone prepared by this invention serves not merPly as a precursor for use-ful anti-tumor substances, but also as a new and sensitive reagnet for certain metal ions, including cobalt (II) nickel (II~, copper (II), and zirconium (IV). In the presence of the above divalent ions, a dilute ~.02-.Od M) solution of (~)-daunomycinone in methanol was colored purple, and with zirconium (IV) a salmon pink color de-veloped~ The limit of detection by eye for cobalt (II~
was 3 X 10-8 M.

Optical resolution of synthetic (+)-daunomycinone is carried out by the conventional method of conversion to diastereomeric derivatives using a chiral resolving agent (Ct. Eliel, "Stereochemistry of Carbon Compounds", McGraw Hill, lg62, Chapter 4~. In the preferred variant, (+)-~O ~
0(36~ -23-

7~S

daunomycinone is monoesterified with l-menthoxy acetyl chloride in pyridine, the diastereomeric C-7 esters separated by careful chromatography, and the ester derived from the (+)-~aunomycinone cleared with dilute base to give ~+)-daunomycinone.

The daunomycinone and the analogs thereof may be converted to the corresponding glycosides by methods well known and disclosed in the art.

~4~(37) _24-~73~

EXAMPLE I
.
2-(2',5'-Dimethoxybenzoyl)-6-methoxybenzoic acid (I?

3-Methoxyphthalic anhydride (17.8 g, 0.1 mole) was suspended in 100 ml. d~y methylene chloride (previously distilled over anhydrous potassium carbonate). To the sus-pension was added anhydrous aluminum chloride (30.5 g, 0.23 mole) in one portion. The suspension quickly became bright yellow and was stirred at room temperature for 2 hours. A solution of p-dimethoxybenzene (27.6 g, 0.2 mole) in ~,ethylene chloride (100 ml) was added slowly to the viyorously stirred solution. The reaction mixture was stirred overnight at 25 and poured onto ice (300 g~
and concentrated hydrochloric acid (S0 ml). The slurry was stirred fvr 30 minutes and extracted with chloroform ~4 X 150 ml). A white precipitate suspended in the aqueous layer is collected by filtration. The or~anic ex- -tract was washed once with water (200 ml) and washed with saturated sodium bicarbonate (4 X 150 ml). The aqueous bicarbonate extract was washed once wi~h chloroform (150 ml) and acidified with concentrated hydrochloric acid, the mixture cooled on an ice bath and filtered.
The residue was washed well with water and dried unaer reduced pressure and combined with the white precipi~ate to yield 2-(2',5'-dime~hoxybenæoyl~6-methoxybenzoic acid (I) as a pale yellow solid (13 g, 41% yield), m.p.
180-182~C (from ethanol); IR (XBr) 2.95, 5.72~; NMR

(CDC13) ~, 7.60-6.80 (m, 6H), 6.10 (s, lH), 3.75 (s, 3H), 3.70 ~s, 3H), 3.49 (s, 3H).

~73~

In accordance with the foregoing procedurPs, but where in place of p-dimethoxybenzene, ~here is usPd hydro-quinone, there is obtained the corresponding 2-(2',5'-dihy-droxybenzoyl)-6-methoxybenzoic acid.

In accordance with the foregoing procedures, but where in place of 3-methoxyphthalic anhydride, there is utilized 3-acetoxy, or 3-benzoyloxyphthalic anhydride, there are obtained the corresponding 2-(2',5'-dimethoxy benzoyl)-6-acetoxy, and 6-benzoyioxybenzoic acids.

In accordance with the i~mediately foregoing al-ternate procedure where in place of p-dimethoxybenzene there is utilized hydroquinone, there are obtained the corres-: ponding 2-(2',5'-dihydroxyhenzoyl)-6-acetoxy, and 6-benzoyl-oxy benzoic acids.

EXAMPLE II

1,4,5-Trimethoxyanthraquinone (II) 2-(2',5'-Dimethoxybenzoyl)-6-methoxybenzoic acid (I) ~3 g, 0.01 mole) was added in portions to stirred concentrated suluric acid (20 ml). After addition the mixture was heated on steam bath wi~h constant stirring for 20 minutes, cooled to room temperature and poured onto crushed ice (400 g) and extracted with chloroform (3 X
100 ml). The organic extract was washed with 2% agueous sodium hydroxide solution (10 X 100 ml) and water (100 ml), then dried over anhydrous sodium sulfate and the solvent ~tripped off under reduced pressure to yield 1,4,5-tri-methoxyanthraquinone (II), as a brownish yellow solid 34(28) -26-73~

(2.7 g, 90~ yield). ~ecrystallization from ethanol gave yellow crystals, m.p. 201-203C; IR (CDC13), 5.9~u; NMR (CDC13) ~ 7.88-7.20 (m, SH), 3.94 (s, 3H), 3.92 (d, 6H). Calcd: C, 68.46; H, 4-70. Found: C, 68.33;
H, 4.82.

In accordance with the above procedures, but starting with any of the other benzoic acids prepared in accordance with Example I, therP are obtained 1,4-dihy-droxy-5-methoxyanthraquinone, 5-acetoxy-1,4-dimethoXy anthraquinone, 5-benzoyloxy-1,4-dimethoxyanthraquinone, S-acetoxy-1,4-dihydroxyanthraquinone D and 5-benzoyloxy-1,4-di~ydroxyanthraguinone respectively.

EXAMPLE III

S-Methox uin~zarin uinone (III) yq q 1,4,5-Tximethoxyanthraquinone (II3 (0.596 g, 2 mmole) was dissolved in hot acetone (60 ml) and argentic oxide ~1 g, 8 mmole) was added to this warm snlution.
Brief sonication formed a uniform dispersal of oxidant.
The mixture was hea~ed up to boiling on steam bath again and the mix~ure stirred vigorously with magnetic stirrer.
The oxidation was *hen initiated by the addition of 6N

aqueous nitric acid (2 ml)~ After addi~ion, the mixture was stirred while cooling for an extra 20 minutes and filtered. The residue was washed thoroughly with water and dried under reduced pressure to give 5-methoxyquini-zarinquinone ~III) as a brownish yellow solid, ~0.44 g, 82~ yiela) ~ m.p~ 252~-3C ~decomp.); IR (KBr), 5.94, 6.05JU;

-27~

~73~L~

NMR ~CDC13)~ ,7.80-7.20 ~m, 3H~, 6.84 (s, 2H), 3.96 ~s, 3H). Calca: C, 67.1; H, 2.98. Found: C, 66.4; H, 2.92.

In accordance with the above procedure, but where in place of 1,4,5-trimethoxyanthraquinone there is utilized 5-acetoxy-1,4-dimethoxyanthraquinone or 5-benzoyloxy-1,4-dimethoxyanthraquinone, there is obtained the corresponding 5-acetoxyquinizarinquinone or 5-benzoyloxyquinizarinquinone.

EXAMPLE IV

5-Methoxyquinazirin~uinone (I _ A mixture of 1,4-dihydroxy-5-methoxyanthra-quin~ne (80 mg, 0.3 mmole), lead tetraacetate (180 mg, 10%
acetic acid) and acetic acid (0.~ ml) was ground together in a 5 mlO flask for lO minutes at 25. The reaction mix-ture was fil'ered and the solid washed with water. The crude solid was taken up in a larye ~olume of acetone, the solution filtered thrsugh Celite, dried over sodium sul-fate and evaporated under reduced pressure to give 5-methoxyquinizarinquinone (48 mg, 60% yield). The spectra and mp of this diquinone were identical with those of the 2~ sample synthesized by the method of Example III.

' In accordance with the above procedure but where in place of l,~-dihydroxy-5~methoxyanthraquinone there is utilized 1,4-dihydrsxy-5-acetoxyanthraquinone or 5-benzoyloxyan~hraquinone, there is obtained the cor-responding S-acetoxyquinizarinquinone or S-benzoyloxy-quinizarinquinone.

-2~-73~
EX~MPLE V

Regioisomeric mixture of 1- and 4-methyl ethers of 6a, 7,10,10a tetrahydro-l,9- and 4,9-dihydroxy-5,6,11,1~-naphthacenetetraone 9-acetate (IV~

5-Methoxyquinizarinquinone (II~) (0.3 g, 1.12 mmole) and 2-acetoxy-1,3-butadiene (2.4 g, 21.4 mmole) were stirred in a mixed solvent of xylene (10 ml) and acetic acid (20 ml) at room ~emperature ~or 4 days. A
yellow solid precipitate separated and was washed well with water. After drying under reduced pressure and filtration through silica gel to remove polymers, a yellow solid comprising the regioisomeric mixture of 1- and 4^methyl esters of 6a,7,10,10a-tetrahydro-1,9-and 4,9-dihydroxy-5,6,11,12-naphthacenetetraone 9-acetate (IV) was obtained (0.3 g, 71% yield). m.p. 165-9CJ

IR (.CDC13~, 5.71, 5.83, 6.01y; NMR (CDC13) ~j, 7.~5-7.32 (m, 3H), 5.50 ~m, lH), 4.05 (s, 3H), 3.80-3.45 ~, 2H), 2.70-2.35 (m, 4H), 2.20 (s, 3H).

In accordance with the abov~ procedures, but where in place of 2-aoetoxy-1,3-butadiene there is utilized 2-propionoxy- or 2-benzoyloxy-1,3-butadiene, there is obtained ~he corresponding 9-propionate, or 9-benzoate respectively.

Similarly, but where in place of 5 methoxy-quinizarinquinone, there is utilized 5-benzoxyquiniza-rinquinone, there is obtained a r~gioisomeric mixture of the analogues l-benzyl and 4--benzyl ethers.

~7;~5 Similarly, but where in place of 5-met~,oxy quiniza~i~quinone, there is utilized 5-acetoxyq~inizarin-quinone or 5-benzoyloxyquinizarinquinone, there is obtained a regioisomeric mixture of 6a,7,10-tetrahydro-1, 9- and 4,9-dihydroxy-5,6,11,12-naphthacenetetraone-l,9-diacetate and 4,9-diacetate or 9-acetate l-benzoate and 9-acetate 4-benzoate respectively.

- Similarly, to the principal procedure, ~ut where in place of 5-methoxyquinizarinquinone, there is o utilized 5-hydroxy~uinizarinquinone, there is obtained the mixture of regioisomers of 6a,7,10,10a-tetrahydro-1, 9- and 4,9-dihydroxy-5,6,11,12-naphthacenetetraone 9-esters.

EXAMPLE VI

Regioisomeric mixture of l-methyl and 4-methyl ethers of 7,10-dihydro-1,6,9,11- and 4,6,9,11-~etrahydroxy-5,12-naphthacene dione 9-acetate (V) A regioisomeric mixture of 1- and 4-methyl ethers of 6a,7,10,10a-~etrahydro-1,9 and 4,9-dihydroxy-5,6,11,12-naphthacenetetraone 9-acetate (IV) ~0.38g, 1 mmole) was dissolved in 10 ml. glacial acetic acid at 130-140. To ~o this solution was added anhydrous sodium acetate (0.164 g, 2.0 mmole) in portions. After addition, the mixture was heated for an extra 2 minu~es and cooled to room tempera-~ure. Sufficient water was added to precipitate the product. The precipita~e was washed well with water and dried under reduced pressuxe to give an isomeric mixture of l-methyl and 4-methyl ether of 7,10-dihydro-1,6,9,11-~73g~5 and 4,6,9,11-tetrahydroxy-5,12-naphthacenedione-9-aceta~e (V) as a red solid (0.37 g, 100% yield). m.p. 222-6C.
IR (C~C13), 5.70, 6.18~; NMR (CDC13)~, 13.80 (d, lH), 13.40 (d, lH), 8.04-7.28 (m, 3H), 5.60 (m, lH), 4.04 (s, 3H), 3.50 (m, 4H), 2.20 (s, 3H).

In accordance with the above procedure, but starting with ~ny of the compounds prepared in accordance with Example V, there are obtained the corresponding regioisomeric mixtures of 7 t 10-dihydro-1,6,9,11- and 4,6,9,11-tetra-hydroxy-5,12-naphthacenedione 9-ester derivatives.

EXAMPLE VII

Resioisomeric mixture of l-methyl and 4-methyl ethers of 7,10-dihydro-1,6,11- and 4,6,11-trihydroxy-5,9,12(8H)-naphthacene-trione (VI) The red enolacetates (V) (33.8 my, 0.09 mmole) were suspended in ethanol (5 ml~. The suspension was degassed and flushed with nitxogen. 6N hydrochloric acid ~3.1 ml) was added to the mixture which was again degassed and flushed with ~i~rogen. The mixture was s~irred at 80-85 for 6 hours, cooled to room temperature and diluted with water (20 ml). The mixture was extrac~ed with chloroform (3 X 15 ml) and the chloroform extract was washed once with water (20 ml) and dried over anhydrous sodium sulfate.
The solvent was stripped off under reduced pressure to give a dar'~ red residue (31 mg). The residue was chromatographed on silica prep plates ~elutiny with S~ hexane in chloroform) to give a regioisomeric mixture of l-methyl and 4-methyl ethers of 7,10-dihydro-1,6,11- and 4,6,11-trihydroxy-5,9, 3~5 12 t8H) -naphthacenetrione ~VI), as a dark red solid t25.2 mg, 84% yield~. m.p. 230-234C (decomp ~; IR
(CDC13), 5 . 80 , 6 . 18~u; NMR (CDC13) ~, 13.81, 13.30 (singlets, two phenolic protons of the 4-methoxy isomer), 13.70, 13.~1 (singlets, two phenolic protons of the l-methoxy isomer), 8.00-7.20 (m, 3H~, 4.0~ (s, 3H), 3.60 (d, 2H), 3.20 (m, 2H), 2.64 (m, 2H).

- In accordance with the above procedure but where in place of the 9-acetate there is used the 9-benzoate, the same product is obtained.

Similarly, where the mixture of l-benzyl and 4-benzyl ether is used in place of the corresponding l-methyl and 4-methyl esters, the corresponding l-benzyl an~ 4-benzyl ether mixture is obtained.

In accordance with the above procedure but starting with the regioisomeric mixtures of 7,10-dihydro-1,6,9,11 and 4,6,9,11-tetrahydroxy-5,12-naphthacenedione 9-acetate or 9- benzoate, the corresponding mixture of 7,10-dihydro-1,6,11- and 4,6,11-trihydroxy-5,9,12(8H)-naphthacenetriones are obtained.

If in accordance with the above procedure,there is utilized ~he mixture of regioisomers of 6a, 7,10,10a-tetrahydro-l,9- and 4,9-dihydroxy-5,6,~1,12-naphthacenete-trasne 9-esters or ~he corresponding ethers themselves produced in accordance with Example V, the intermediate step of Exampl~ VI may be omitted to yield the foregoing products dlrectly.

.
. . -EXAMPLE VIII

4-Methyl ether of 7,10-dihydro-4,6,11-trihydroxy-5,9,12(8H)-naphthacenetrione (VII) The mixture of isomers produced in accordance with the principal embodiment of Example VII, (50 : 50) was heated in ethanol to boiling and filtered. The residue was again heated in ethanol to boiling and filtered. The NMR of the second residue showed a better than 90% pure A-methyl ether ~VII). m.p. 242-245C (decomp.). Calcd.e C, 67.46;- H-, 4.14. Found = Ct 66.97; H, 4.31.

In accordance with the foregoing procedure similar treatment of the other regioisomers produced in ~ccordanoe with Example VII provides a means of separating saîd regioisomers into the corresponding 1- and 4-isomeric components.

EXAMPLE IX

4-Methyl ether of 9-ethynyl-7,10-dihydro-4~6,9,11-tetrahydroxy-5,1?(8H~naphthacenedione (VIII)_ Acetylene, purified by passing it first through a column of alumina, then thxough concentrated sulfuric acid, was bubbled rapidly through freshly distilled tetrahydrofuran (50 ml) under nitrogen for 1 hour. Ethyl-mag~esium bromide (4 ml, 3.15 M in ether, 12.6 mmole) was added in portions. When the frothing subsides, poxtionwise addition of the ethylmagnesium bromide solution was continued until the total solution had been Added. The passage of ;lf. D9734S
acetylene was stopped and 4-methyl ether of 7,10-dihydro-4,6,11-trihydroxy-5,9,12(8H) naphthacenedione (VII) ~40 mg, 0O12 mmole~ in dry tetrahydrofuran (50 ml) was added drop-wise. After addition was completed, the mixture was stirred at room temperature under dry nitrogen overnight.
The dark blue solution was added carefully to cooled saturated aqueous ammonium chloride (200 ml) and then - aqueous phase extracted with ethyl acetate (2 X 50 ml).
The ethyl acetate extracts were combined with tetrahydro-furan solution and washed once with saturated aqueous sodi~n chloride, then water, dried over anhydrous sodium sulfate and the solvent removed to give a dark residue.
T~e residue was chromatographed on silica prep plates, elution with 3% methanol/methylene chloride yielded 4-methyl ether of 9-ethynyl-7,10-dihydro-4,6,9,11-tetrahy-droxy-5,12(8H)-naphthacenedione (VIII) (21.9 mg, 50~ -yield~. IR (CDC13), 2.77, 3.04, 6.19~; NMR (CDC13)~, 13.88 (s, lH, 13.48 (s,lH), 8.23-7.20 (m, 3H), 4.07-4.01 (d, 3H), 3.20-2.90 (m, 4H), 2.48 (d, lH), 2.10 (m, 3H;
OH and CH2); mass spectrum, m/e 354 (M~), 346.

In accordance ~ith the above procedure but where in place of the 4-methyl e~her there is utili~ed the corresponding 4-hydroxy compound itself or the 4~benzyl ether, there i5 obtained the corresponding 9-ethynyl-7,10-dihydro-4,6,9,11-~.2trahydroxy-5,12(8H)-naphthacenedione or the 4-benzylether thereof.

In accordance with the foregoing procedures but where there is used as starting material any of the 1- and 4-regioisomeric mixtures prepared in accordance with Ex~mple VII, there are obtained the correspondinq 1- and ~i973~S

4-regioisomeric mixtures of the appropriate 9-ethynyl carbinols.

EXAMPLE X

(+)-7-Deoxydaunomycinone (IX) -To a warm vigorously stirred solution of yellow mercuric oxide (78 mg) in water (3 ml) and concentrated sul-furic acid (0.5 ml) was added quickly to a solution of 4-m~t~.yl ether of 9-ethynyl-7,10-dihydro-4-6,9,11-tetrahy-droxy-5,12(8H)naphthacenedione (VIII) (26 mg, 0.07 mmole) in chloroform (5 ml). The mixture was then heated at 70-80 for 4 hours, cooled to room temperature, pGured into water (20 ml) and extracted with chloroform (2 X 15 ml).
The organic extracts were washed in brine, then water, then dried over anhydrous sodium sulfate. The residue was chromatographed on silica prep plates to give a racemic mixture of (+)-7-deoxydaunomycinone (IX) (10.9 mg, 40% yield~. NMR(CDC13)~ , 13.94 (d, lH), 13.54 (s, lH),

8.04-7.28 (m, 3H), 4.03 (s, 3H), 2 0 98 (m, 4H~, 1.92 ~m, ~H); Mass spectrum m/e 382 (M+), 364, 339, 321. The spectroscopic and chromatographic properties of this ma-terial were identical with 7-deoxydaunomycinone from natural ~+)-daunomyc.inone.

In accordance with the above procedure but wher~
in place of the 4-methyl ether, the 9-ethynyl-7,10-dihydro-4,Ç,9,11-tetrahydroxy-5,12(8H) naphthacenedione itself is utilized, there is obtained (~)-7-deoxycarminomycinone, rf (in 3% MeOH-CH2C12) = 0.44, rela~ive to daunomycinone (~f = 0.14).

Similarly, where, in place of the 4-methyl ether there is used the ~-benzyl ether, there is obtained (+)-7-deoxycarminomycin~ne 4-benæylether.

Further, in accordance with the above procedure where any of the 1- and ~-regioisomeric mixtures of 9-ethynyl carbinols prepared in accordance with Example IX, are used as the starting material, there are obtained the corresponding 1-and 4-regioisomeric mixtures o~ the appropriate 9-acetyl carbinols.

o ~XAMPLE XI
-Regioisomeric mixture of 1- and 4-methyl ethers of 9-acetyl-7,10-dihydro-1,6,9,11- and 4,6,9,11-tetrahydroxy-5,12(8~)-naphthacenedione 9-acetate .
Regioisomeric mixture of 1- an~ 4-methyl ethers of 9-ethinyl-7,10-dihydro-1,6,9,11- and 4,6,9,11-tetrahydroxy-5,12(8H)-naphthacenedione (15 mg, 0.04 mmole) and mercuric acetate (75 mg, 0.24 J~mole~ were suspen~ed in ethyl acetate (10 ml) and the mixture stirred at room temperature overnight. Hydrogen sulfide gas was bubbled through until no more ~lack precipitate was formed. The reaction mixture was filtered through celite and the filtrate evaporated to dryness~ The residue was chromatographed on silica prep plate~ eluted with 10% hexane/chloroform to give ~n regioisomeric mixture of 1- and 4-methyl e~her of 9-acetyl-7,10-dihydro-1,6,9,11- and 4,6,9,11-tetrahvdroxy-5,12(8H)-naphthacenedione 9-acetate (4.2 mg, 25% yield). IR (CDC13), 5.75, 5.82, 6.19~; NMR (CDC13) ~, 13.92 (s, lH), 13.52 3~5 ~s,l~), 8.~4-7.28 (m, 3H), 4.04 ~s, 3H), 3.26-2.90 (m, 4H)~ 2.40-2.20 (m, ZH), ~.22 (s, 3H), 2.04 (s, 3H);
MS, m/e, 424 (M+, 7%), 434 (3%), 374 (39%), 364 (100%).

In accordance with the above procedure but where in place of the mixture of 1- and 4-methyl ethers, there are utilized the corresponding 1- and 4-benzyl ethers, there is obtained the corresponding mixture of the appropriate

9-acetyl acetate. When however, the mixture correspondlng to 1- and 4-hydroxy compounds is reacted according to the above procedure there is obtained directly a mixture of the l-hydroxy isomer of (+)-7-deoxydaunomycinon2 and (+)-7-deoxy-carminomycinone, respectively in 73% total yield.

In accordance with the above procedures, but where in place of the regioisomeric mixtures there is utilized the appropriate 4-ether compound per se pro~ueed in accor~ance with Example IX, there is obtained the corres-ponding 9-acetyl acetate.

In accordance wit~ all of the foregoing procedures ~t where in place of mercuric acetate~ there is utilized mercuric trifluoroacetate, mercuric propionate, mercuric valerate, or mercuric benzoa~e, ~here are obtained from the ethers ~VIII) the corresponding 9-acetyl trifluoro-acetate,propionates, valerates or bQnzoates, respectively.

EXAMPLE XII

Regioisomeric mixture of (~)-7-Deoxydaunomycinone and its l-me~hoxy isomer .

Regioisomeric mixture o~ 1~ and ~-methyl ethers 9-acetyl-~,10-dihydro-1;6,9,11- and 4,6,9,11-tetrahydroxy-_~7._ ~

~ 73~

5,12(8H~-nap~thacenedione-9-acetate (3 mg, 0.07 mmole) was dissolved in ethanol ~g ml) and water (1 ml). The solution was degassed and flushed with ni~rogen 3 times. To the resulting mixture was added 0.05N agueous sodium hydroxide (1 ml) and the resultant solution degassed and flushed with nitrogen. The mixture became dark blue and was stirred at room temperature for 3 hours. The reaction mixture was poured onto crushed ice (10 g) and 3N aqueous hydro-chloric acid and extracted with ethyl acetate (2 X 10 ml3.

The extract was washed with water and dried over anhydrous sodium sulfate. The solvent stripped off under reduced pressure and the residue chromatographed on silica prep plate, and eluted with 10% hexane/chloroform to give a mixture of 5~)-7-deoxydaunomycinone and its l-methoxy regioisomer (2.7 mg, 100% yield~.

In accordance with the foregoing procedures, but starting instead with any of the other 9-acetyl-9-esters produced in accordance with Example XI, there is produced the corresponding 9-acetyl carbinol.

~ EX~MPLE XIII

Daunomvcinone and epi-dauno~ycinone a) Dry nitrogen was hubbled rapidly ~hrough a solution of (~)-7-deoxydaunomycinone (7.1 mg) in carbon tetrachloride ~50 ml~. The solu~ion was irradiated with a GE-sunlamp while a solution o bromine in carbon tetrachloride (2 ml, 0.1 M) was added very slowly with stirring. The reaction is periodically monitored using h.p.l.c. (three -3~-3~9~3~

X 1/8" Corasil columns elu~ed with chloroorm in a Waters h.p.l.c.unit, ~low rate .6 ml/min.). Bxomine addition and irradiation are continuPd for 2-3 hours until h.p.l.c.
shows disappearance of over 80% of the starting material.
The solutiGn is concentrated and the residue was taken up in chloroform.

b) An 0.5 mm silica gel tlc plate (F-254, EM Lab #5769-9H3 was pretreated by elution with 3~ methanol in methylene chloride and allowed to air dry in a hood.

The chloroform solution was ~hen carefully applied and the plate eluted as usual with 3% methanol in methylene chloride. Bands corresponding to (+)-daunom~cinone (Rf = 0.27), (+)-7-epidaunomycinone (Rf = 0.25) and a little starting material (R~ = 0.5) were separately iso-lated, extracted with 10~ methanol in methylene chloride and concentra~ed. The above Rf values refer to hydrated plates. Each residue was taken up in chloroform and fi~tered through a glass fiber plug and concentrated.

From this procedure there are obtained the following products:
(+)-daunomycinone (1.3 mg), (+)-7-epidaunomycinone (2.1 mg) and (~)-7-deoxydaunomycinone (1.0 mg. starting material).

. . .
Tn accordance with the foregoing ~rocedure, but where in place of (~)-7-deoxydaunomycinone ther is u~ilized (~3-7-deoxycarminomycinone and other 4-ethers of (~)-7-deoxycarmino-mycinone, there i5 obtained t 3-carminomycinone, (~)-7-epi--3~-73~S

carminomycinone, and (~)-7-deoxyc~rminomycinone(starting material), all ~f which are separable from each o~her, and the corresponding 4-ethers thereof when the ap~ropriate (+)-7-deoxy-4-et~.ers are used as starting materials.

EXAMPLE XIV

Epimerization of (+)-~-epidaunomycinone to (+)-daunomycinone The (+)~7-epidaunomycinone (2.4 mg) above was taken up in trifluoroacetic acid (1.5 ml) and the solution allowed to stand 2 hours at room temperature. The reaction w~^s poured into water (5 ml), extracted with chloroform and the chloroform washed well with water, then dried over sodium sulrate.
ChrDma~ography as described above (3% methanol/methylene chloride) gave (+)-daunomycinone as the major product (1.8 mg) accompanied by ~race~ of 7-epidaun~mycinone, a non-polar purple band, and 2 less polar orange bands. Th~
identity o this daunomycinone was confirmed by ms and h.p.l~c. analysis (same system as before, flow rate 1.0 ml chloroorm 3/min.) by comparison wi~h ~ daunomycinone derived from natural daunomycin.

In accordance with the foregoing procedure, but starting with ~ 7-epicarminomycinone or any of the other tl)-7-epicarminomycinone 4-ethers, there are obtained the corresponding (+)-caxminomycinone ~nd (+)-7-carminomycinone 4-ethers.

--~0--~73~L~

EXAMPLE XV

Resolution of (+)-daunomycinone Recamic daunomycinone (10 mg) is taken up in dry benzene (2 ml) and dry pyridine (3 drops) are added, fol-lowe~ by freshly prepared l-menthoxyacetyl chloride ~30 mg~.
The reaction mixture i5 refluxed for 30 minutes, allowed to cool, then poured into water and extracted with chloro-form. The chloroform extracts ~re combined, washed with 5% aqueous oxalic acid, followed by water and brine. The chlorol~rm ar~ dried over anhydrous sodium sulfate, concen~rated at reduced pressure, and the residue applied to a preparative thin-layer plate of silica gel. Elution with 3% methanol in me~hylene chloride (v/v) produces an orange band between Rf = O.3 and O.38. The segment at Rf - 0.33 i~ carefully removed and extracted with 10%
meth~nol in methylene chloride, then the eluate concentrated and rechro~atographed in the iden~ical manner. There is thus obtained the l-menthoxyacetyl ester (at C-7 OH) of ~+)-daunomycinon~.

The l-menthoxyacetyl ester is dissolved in ethanol (2 ml~, the solu~ion degassed and flushed with ni-trogen three times, and several drops of 2M sodium hydroxide are added. The resul~ing solution is again degassed and f~ushed with nitrogen, then stirred at 25 for 3 hours.
The mixture is poured onto ice and dilute aqueous oxalic acid, extracted with chloroform, the extracts washed and dried over anhydrous sodium sulfate. After solvent re-moYal, the residue is chromatographed on silica and the (f ~ -daunomycinone isolated.

:~7~
EX~PLE XVI

4-O~Demethylation of daunomycinone derivatives a) Natural daunomycinone (14.7 mg) was taken up in anhydrous ~enzene (100 ml). Sea sand (1 g) was added and the mixture was stirred until all the daunomycinone went into solution. The reaction~was stirred under nitro-gen and anhydrous aluminum chloride~ (0.22 g) was added.
The reaction gradually turned purple; stirring was con-tinued at room temperature overnight. The reaction was 0 w~rked up by pouring in aqueous oxalic acid (25 ml., 25%) a~d the layers mixed thoroughly until the color was dis-charged. The aqueous phase was extracted once with chloroform (10 ml) and the chloroform added to the benzene.
The combined organic phases were ~shed once with watPr, dried over anhydrous sodium sulfate and concentrated to give (+~-carminomycinone, R~ = 0.16 (on silica gel, 3%
methanol in methylene chloride, V/V3O The mass spectrum showed 384 (M~, 45%3, 366 (7%), 348 (100%), 341 (3%), 333 ~21%), 323 (67%), 305 (19%), 295 (39%), 277 ~1~%), ~49 (8%).
!0 The NMR (C~C13) taken using Fourier-transform spectroscopy gave ~ 13.47, 12.96, 12~17 (s, lH ea~; 7.14-7.25 (m, 3H), .43 (s, 3~), 2.27 (m, 2H~; the w spectrum showed ma~ma at 527~ 512, 492, 480 and 466 nm.

Application of the above demethylation to racemic daunomycinone proc~eds in the identical manner to yield arminomycinone.

-4~-1!~97345 b) Treatment of 11.5 mg of 7-deoxydaUnymycinone in dry benzene (45 ml) with sea sand (0.5 g) and anhydrous aluminum chloride (0.1 g) under dry nitrogen overnigh~, as in the Example above, followed by work-up as described above gave 7-deoxycarminomycinone (10.9 mg), Rf = 0.44 (3% methanol in methylene chloride v/v), MS 368 (27~), 327 (33%), 326 (21%), 325 (100%), 307 (20%), NMR (CDC1 13.62, 12.Bl, 12.28 (s, lH ea). 7.84-7.25 (m, 3H), 2.38 (s, 3H).

c~ A suspension of the 4-methyl ether of 7,10-~inydro-4~6~ll-trihydroxy-5r9~l2(8H)-naph~hacenetrione (VII, Rl = C~3) (20 mg,.06 mmole) in anhydrous methylene chloride (ml ml) was stirred at room temperature under dry nitrogen with an excess of anhydrous aluminum chloride (133 mg, 1 mmole). After 16 hours, the reaction was quenched with 5~ aqueous oxalic acid as in the above pro-cedure and the demethylation product isolated by chloroform (3 X 20 ml) extraction, water wash (2 X 20 ml), drying over sodium sulfate and solvent removal. There was obtained 17 mg. o~ the red trihydro~y compound, MS 324 (M~3, NMR
(CDC13)~ 13.64, 12.74, 12.22 (s, 1~ ea), 7.88-7.2~ (m, 3H), 3.60 (s, 2H), 3.21 (t, 2H), Z.62 (t, 2H).

EXAMPLE ~VII
-_eference chromatographic values for synthetic materials Vsing 250~ thickness precoated silica gel GF
plates from Araltech (Uniplates) and an eluting solvent of 3% methanol in methylene chloride ~V/V), the following Rf values were reproducibly observed (~ .01):

73~5 daunomycinone 0,14 7-deoxydaunomycinone 0.26 ~+)-7-epidaunomycinone0.08 (+)-carminomyc.inone0.16 (+)-7-epicarminomycinone 0.13 (+)-7-deoxycarminomycinone 0.44 This application is a division of Canadian Application Serial No. 265,482, filed November 12, 1976.

' .

Claims (6)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. The process of preparing a mixture of the 1- and 4- regioisomers of the formula:

wherein R1 is hydrogen, a lower alkyl of 1-5 carbon atoms;
phenyl- or substituted phenyl-lower alkyl wherein the sub-stituent groups are lower alkyl, lower alkoxy, each containing 1-5 carbon atoms, or halo;. and lower alkyl contains 1-5 carbon atoms and comprises-reacting a compound of the formula:

with an acid wherein R8 has the same value as R1.

2. The process of Claim 1, wherein R1 is methyl, benzyl or hydrogen.

3. The process of Claim 1, wherein R1 is methyl.

4. A mixture of the 1- and 4- regioisomers of the formula:

wherein R1 is as defined in Claim 1, when prepared by the process defined in Claim 1 or by an obvious chemical equiva-lent.

5. A mixture of Claim 4 wherein R1 is methyl, benzyl or hydrogen, when prepared by the process defined in Claim 2 or by an obvious chemical equivalent.

6. The component of the mixture of Claim 4 having the formula:
when prepared by the process defined in Claim 3 or by an obvious chemical equivalent.