NZ617613B2 - Process for the production of estetrol intermediates - Google Patents

Abstract

Disclosed is a process for the preparation of a compound of formula (I), said process comprising the steps of : a) reacting a compound of formula (II), with an acylating or a silylating agent to produce a compound of formula (III); b) reacting the compound of formula (III) in the presence of palladium acetate or a derivative thereof to produce compound of formula (IV); and c) reacting the compound of formula (IV) with a reducing agent to produce compound of formula (I). The compound of formula I can then be used to produce estetrol. um acetate or a derivative thereof to produce compound of formula (IV); and c) reacting the compound of formula (IV) with a reducing agent to produce compound of formula (I). The compound of formula I can then be used to produce estetrol.

Description

PROCESS FOR THE PRODUCTION OF ESTETROL INTERMEDIATES Field of the invention The present invention relates to a new process for the synthesis of a key intermediate in the synthesis of Estetrol.

BACKGROUND OF THE INVENTION Estrogenic substances are commonly used in methods of Hormone Replacement Therapy (HRT) and methods of female contraception. Estetrol is a biogenic estrogen that is endogenously produced by the fetal liver during human ncy. Recently, estetrol has been found effective as an estrogenic substance for use in HRT. Other ant applications of estetrol are in the fields of contraception, therapy of auto-immune diseases, prevention and therapy of breast and colon tumors, enhancement of libido, skin care, and wound healing.

The synthesis of estetrol and tives thereof is known in the art. Verhaar M.T; et al () describes a process for the preparation of estetrol starting from a 3-A- oxy-estra 1,3,5(10),15-tetraenone, wherein A is an C1-C5alkyl group, or a benzylic group. In this document, 3-A-oxy-estra 1,3,5(10),15-tetraenol is prepared in 6 steps from estrone where A is a benzyl group, the steps comprising protection of the 3-OH group by a benzyl group, then transformation of the o-group to a ethylenedioxy derivative which is halogenated at the C15 on using pyridinium bromide perbromide. ohalogenation is carried out by using potassium oxyde in dimethylsulfoxide. Deprotection of the 17-keto-group is conducted using p- toluene-sulfonic acid monohydrate in aqueous acetone. Reduction of 17-keto-group affords the 17-ol derivative.

One of the disadvantages of the process bed in WO 41839 is the protection of 3-OH function with a benzyl group which can be removed only by hydrogenation using Pd/C as catalyst in the last steps of the estetrol synthesis. Furthermore the level of this catalyst in the final drug substance must be determined and must comply with the ICH guidelines.

Another disadvantage of the synthesis described in WO 41839 is the two step protection/deprotection of the 17-keto function in order to generate the 15-16 double bond.

There remain a need for an improved synthesis of 3-Protected-oxy-estra-1,3,5(10),15- tetraeneol.

WO 64096 It is therefore an object of the present invention to provide a process for the preparation of 3-Protected-oxy-estra-1,3,5(10),15-tetraeneol which overcome at least one the antages of the prior art.

Summary of the invention The present inventors have now found that this object can be obtained by using a process as d in the appended claims.

According to a first aspect of the present invention, a process for the preparation of a compound of formula (I) (3-P1-oxy-estra-1,3,5(10),15-tetraeneol ) is ed: (I) said process comprises the steps of : a) reacting a compound of formula (II), with an ing or a silylating agent to produce a compound of formula (III), wherein P1 and P2 are each independently a protecting group selected from R1CO-, or RZ'Si-RsR“, wherein R1 is a group selected from C1_6alkyl or 03-5cycloalkyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C1-4alkyl; R2, R3 and R4 are each independently a group ed from C1-6alkyl or phenyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C1_4alkyl; HO \0 (II) (III) b) reacting the compound of a (III) in the presence of palladium acetate or a derivative thereof to produce compound of formula (IV); and (IV) c) reacting the compound of formula (IV) with a ng agent to produce compound of formula (I).

Preferably, the present invention encompasses a process for the preparation of a compound of formula (I), said process comprising the steps of a) reacting a compound of a (II), with an acylating or a silylating agent to produce a compound of formula (III), n P1 and P2 are each independently a protecting group selected from RZ'Si-R3R4, or R1CO-, wherein R1 is a group selected from C1_6alkyl or Cs. scycloalkyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C1-4alkyl; R2, R3 and R4 are each independently a group selected from C1-6alkyl or phenyl, each group being optionally substituted by one or more substituents ndently selected from fluoro or C1_4alkyl; b) reacting the compound of formula (III) in the presence of palladium e present in catalytic or sub-stoichiometric amounts, in an oxygen atmosphere to produce compound of a (IV); and c) reacting the compound of formula (IV) with a reducing agent to produce compound of formula (I).

The invention provides an improved process for producing 3-P1-oxy-estra-1, 3, 5(10),15- tetraeneol of formula (I) in significantly higher yield and/or at lower cost than possible by the previous known syntheses.

According to a second , the present ion also encompasses a process for the preparation of estetrol, said process comprising preparing a compound of formula (I) by a process ing to the first aspect of the invention and further ng compound of formula (I) to produce estetrol. ing to a third aspect, the t invention also encompasses estetrol directly obtained by the process according to the second aspect of the invention, for use in a method selected from a method of e replacement therapy, a method of treating l dryness, a method of contraception, a method of enhancing libido, of method of treating skin, a method of promoting wound healing, and a method of treating or preventing a disorder selected from the group consisting of autoimmune diseases, breast tumors and colorectal tumors.

The above and other characteristics, features and advantages of the present invention will become apparent from the following ed description, which illustrate, by way of example, the principles of the invention.

Detailed description of the invention It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

As used herein, the singular forms a , an", and "the" include both singular and plural referents unless the t clearly dictates othenNise.

The terms "comprising , comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", ins", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprisingII II , comprises" and "comprised of" as used herein comprise the terms "consisting of", "consists" and "consists of".

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the tive ranges, as well as the recited endpoints.

All references cited in the present specification are hereby incorporated by reference in their ty. In particular, the ngs of all references herein specifically referred to are orated by reference.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the t invention.

In the following passages, different aspects of the invention are defined in more detail.

Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being red or advantageous may be combined with any other feature or features indicated as being red or advantageous.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in s places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any le manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features ed in other ments, ations of features of different embodiments are meant to be within the scope of the ion, and form different embodiments, as would be understood by those in the art.

For example, in the appended claims, any of the claimed embodiments can be used in any combination.

The term “alkyl” by itself or as part of another substituent, refers to a straight or branched saturated hydrocarbon group joined by single carbon-carbon bonds having 1 to 6 carbon atoms, for e 1 to 5 carbon atoms, for example 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. Thus, for example, C1_6alkyl means an alkyl of one to six carbon atoms. Examples of alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, terf-butyl, 2-methylbutyl, pentyl iso-amyl and its isomers, hexyl and its isomers.

The term “03-6cycloalkyl”, as a group or part of a group, refers to a saturated cyclic alkyl radical containing from about 3 to about 6 carbon atoms. Examples of monocyclic cloalkyl radicals e cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

The term lkenyl” by itself or as part of another substituent, refers to an unsaturated hydrocarbyl group, which may be linear, or branched, comprising one or more carbon- carbon double bonds. Examples of 02-6alkenyl groups are ethenyl, enyl, 2-butenyl, 3-butenyl, 2-pentenyl and its isomers, 2-hexenyl and its s, 2,4-pentadienyl and the like.

The term “Cs_1oaryl”, by itself or as part of another substituent, refers to a polyunsaturated, aromatic hydrocarbyl group having a single ring (i.e. ) or multiple aromatic rings fused together (e.g. naphthyl). or linked covalently, typically containing from 6 to 10 carbon atoms, wherein at least one ring is aromatic. Cs-1oaryl is also intended to include the partially hydrogenated derivatives of the carbocyclic systems enumerated herein. Non- limiting examples of ryl se phenyl, naphthyl, indanyl, or 1,2,3,4-tetrahydronaphthyl.

The term aryIC1_6alkyl", by itself or as part of another substituent, refers to a C1-6alkyl group as defined herein, wherein one or more hydrogen atoms are replaced by one or more Cs-1oaryl as defined . es of aralkyl radicals include benzyl, phenethyl, dibenzylmethyl, methylphenylmethyl, 3-(2-naphthyl)—butyl, and the like.

The term “C1_6alkylcarbonyl”, as a group or part of a group, represents a group of Formula —CO-Ra, wherein Ra is C1_6alkyl as defined herein.

The term “Cg.6cycloalkylcarbonyl”, as a group or part of a group, represents a group of Formula —CO-R°, wherein Ra is 03-5cycloalkyl as defined herein.

The term “Cz_6alkenle1_5alkanoate” refers to a compound having the a Rb-O-CO-Ra wherein Ra is C1_6alkyl as defined herein and Rb is 02-6alkenyl as defined herein.

The term “02-5a|kenyl03-5cycloalkanoate” refers to a compound having the Formula Rb-O-CO-RC wherein RC is cloalkyl as defined herein and Rb is 02-6alkenyl as defined herein.

The term “C1_5alkylenecarbonate” refers to a nd having the Formula Rb-O-CO-O-Ra wherein Ra is C1_6alkyl as defined herein and Rb is 02-6alkenyl as defined The present invention s to a process for preparing 3-P1-oxy-estra-1,3,5(10),15- tetraeneol of formula (I), wherein P1 is a protecting group selected from R1CO-, RZSi-RsR“; wherein R1 is a group selected from C1-6alkyl or 03-5cycloalkyl, each group being optionally substituted by 1, 2 or 3 substituents independently selected from fluoro or C1_4alkyl; preferably R1 is selected from the group comprising methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert—butyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl, each group being optionally substituted by 1, 2 or 3 substituents independently selected from fluoro or C1_4alkyl; more ably R1 is methyl, ethyl, propyl, isopropyl, entyl, or cyclohexyl, yet more preferably R1 is methyl, or ethyl; R2, R3 and R4 are each independently a group ed from C1-6alkyl or phenyl, said C1_6alkyl or phenyl, being optionally substituted with 1, 2 or 3 substituents independently ed from fluoro or kyl; preferably R2, R3 and R4 are each independently selected from the group comprising methyl, ethyl, propyl, isopropyl, butyl, isobutyl, terf-butyl, and phenyl, each group being optionally substituted with 1, 2 or 3 substituents each independently selected from fluoro or C1-4alkyl; preferably R2, R3 and R4 are each independently selected from the group comprising methyl, ethyl, propyl, isopropyl, or tert- butyl, and phenyl, each group being ally substituted with 1, 2 or 3 tuents each independently selected from fluoro or kyl, said process comprises the steps of a) protecting the hydroxyl and the ketone of estrone of formula (II) to produce compound of formula (III), n P1 is as defined above and P2 is a protecting group selected from R1CO-, RZ'Si-RsR“, HO \O (II) (”D b) reacting the compound of a (III) in the presence of ium acetate or a derivative thereof such as palladium chloride or Tris(dibenzylideneacetone)dipalladium (Pd2(dba)3) to produce a compound of formula (IV), preferably in the presence of an oxygen atmosphere; and (IV) c) ng the compound of formula (IV) with a reducing agent to produce compound of formula (I); and if necessary any protective group used in the reactions described above is cleaved rently or subsequently; and if desired, nd of formula (I) is subsequently converted into another compound by routine processes applicable for conversion of functional groups, if desired a compound of formula I thus obtained is resolved into its stereoisomers.

In an embodiment, P1 is R1CO-; preferably P1 is a group selected from C1-4alkylcarbonyl or C4-6cycloalkylcarbonyl, each group being optionally substituted by 1, 2 or 3 tuents independently selected from fluoro or C1-4alkyl; more preferably P1 is a group selected from C1-2alkylcarbony or cloalkylcarbonyl, each group being optionally substituted by 1, 2 or 3 tuents independently selected from fluoro or C1_2alkyl; for example P1 is selected from acetyl, or cyclohexylcarbonyl, preferably P1 is acetyl.

In an embodiment, P2 is R1CO-; preferably P2 is a group selected from C1-4alkylcarbonyl or C4-6cycloalkylcarbonyl, each group being ally substituted by 1, 2 or 3 substituents independently selected from fluoro or C1-4alkyl; more preferably P2 is a group selected from C1-2alkylcarbony or 05.6cycloalkylcarbonyl, each group being optionally substituted by 1, 2 or 3 substituents independently selected from fluoro or C1_4alkyl; for example P2 is selected from acetyl, or cyclohexylcarbonyl, preferably P2 is acetyl.

In an ment, P1 and P2 are each independently R1CO-.

In an embodiment, P1 is RZ'Si-R3R4. Preferably P1 is selected from the group comprising tert—butyI-dimethyl-silyl, diphenyl-methyl-silyl, dimethyl-phenyl-silyl, trimethyl-silyl, triethyl- sinI and triisopropyI-sinI, each group being optionally substituted by one or more substituents independently ed from quoro or C1_4a|kyl; more preferably P1 is tert- butyl-dimethyl-silyl.

In an embodiment, step (a) comprises the steps of (a1) protecting the hydroxyl of compound of formula (II) with a silylating agent to produce a nd of formula (Ila), wherein P1 is RZ'Si-RsR“; and (Ila) (III) (a2) protecting the ketone of compound of formula (Ila) in the presence of an acylating agent to produce compound of formula (III), wherein P2 is R1CO-.

In an embodiment, P2 is R3R4; preferably P2 is selected from the group sing tert—butyI-dimethyl-silyl, diphenyl-methyl-silyl, dimethyl-phenyl-silyl, trimethyl-silyl, triethyl- sinI and propyI-sinI, each group being ally substituted by one or more substituents independently selected from quoro or C1_4a|kyl, more preferably P2 is tert- butyl-dimethyl-silyl.

In an embodiment, P1 and P2 are each independently RZ'Si-R3R4.

In an embodiment, P1 is R3R4; and P2 is R1CO-. Preferably P1 is ed from the group comprising terf-butyI-dimethyl-silyl, diphenyl-methyl-silyl, dimethyl-phenyl-silyl, trimethyI-silyl, triethyI-silyl or triisopropyI-silyl, each group being optionally substituted by one or more substituents ndently selected from fluoro or kyl; more preferably P1 is tert—butyI-dimethyI-silyl; and preferably P2 is a group selected from C1-6a|ky|carbony| or 03.6cycloalkylcarbonyl, each group being optionally tuted by 1, 2 or 3 substituents independently selected from fluoro or C1-4a|ky|; preferably P2 is a group selected from C1-4a|ky|carbony| or 05.6cycloalkylcarbonyl; each group being optionally tuted by 1, 2 or 3 substituents independently selected from fluoro or C1_2alkyl; more preferably P2 is C1-2a|kylcarbony or 05.6cycloalkylcarbonyl, for example P2 is acetyl or cyclohexylcarbonyl, preferably acetyl.

In an embodiment, the silylating agent can be selected from the group comprising C1_5alkylsilylchloride, C1_5alkylsilyltriflate, phenylsilylchloride, phenylsilyltriflate, C1.6aIkylphenylsilylchloride, C1.6aIkylphenylsilyltriflate, each group being optionally substituted by one or more substituents independently selected from fluoro or C1_4a|kyl.

In an embodiment, the process for the ation of 3-P1-estra 1, 3, 5(10),15-tetraene- 17-ol of formula (I) from estrone of formula (II) can be preformed in 3 steps as shown in Scheme 1. The compound of formula (I) can then be further reacted to prepare estetrol.

(II) (III)l o’H /o P1\o O. 1 O.

F’\o (I) (M ---IOH estetrol According to scheme 1, the hydroxyl and the ketone of estrone of formula (II) are both protected, preferably in one step, to produce compound of formula (III).

WO 64096 In an ment, wherein P1 and P2 are each independently R1CO-, estrone is d with an acylating agent. Preferably, said acylating agent is 02-6alkenle1.6alkanoate or 02-6alkenleg-6cycloalkanoate. Preferably, the acylating agent is selected from the group comprising 02-6alkenylpropanoate, 02-5alkenylbutanoate, 02-6alkenylpentanoate, 02-6alkenylhexanoate, 02-6alkenylcyclopropanoate, 02-6alkenylcyclobutanoate, 02-6alkenylcyclopentanoate, and 02-6alkenylcyclohexanoate. More preferably, the acylating agent is selected from the group comprising isopropenyl acetate, isopropenyl propionate, isopropenyl te, isopropenyl isobutyrate, vinyl acetate, vinyl propionate, propenyl cyclohexanecarboxylate, ethenyl cyclopentanecarboxylate, and vinyl exanoate. More preferably, the acylating agent is selected from the group comprising isopropenyl acetate, isopropenyl nate, isopropenyl butyrate, isopropenyl isobutyrate, vinyl acetate, and vinyl propionate.

The acylation can be performed in the presence of an acid, such as in the presence of sulfuric acid, or in the presence of a Cs-1oarylsulfonic acid, optionally substituted by one or more chloro substituents. miting examples of a suitable acid include para-toluene sulfonic acid, and sulfuric acid.

For example, estrone of formula (II) can be was reacted with penyl acetate in the presence of sulfuric acid or para-toluene sulfonic acid to give the estra-1,3,5 (10), 16- ne-3,17-diol, 3,17-diacetate. The on can be performed under reflux, ally under inert atmosphere, such as nitrogen atmosphere. The product can be used as such in the next step or further purified by known techniques in the art such as by chromatography, for example on silica with a suitable eluant such as methylene chloride/hexane or ethyl acetate/hexane.

In an embodiment, wherein P1 and P2 are each ndently RZ'Si-R3R4, estrone of formula (II) is reacted with a silylating agent. The silylating agent can be selected from the group comprising C1-5alkylsilyl triflate, phenylsilyltriflate, C1.6alkylphenylsilyltriflate, C1_5alkylsilylchloride, C1_phenylsilylchloride, C1.6alkylphenylsilylchloride, each group being optionally substituted by one or more substituents independently selected from fluoro or C1-4alkyl.

WO 64096 2012/060447 For example, formation of protected estrone silyl ether can be performed by reaction of a silylating agent such as terf-butyl dimethylsilyltriflate, diphenylmethylsilyltriflate, ylphenylsilyltriflate, trimethylsilyltriflate, triethylsilyltriflate, or propylsilyltriflate.

The reaction can be performed in the presence of a suitable base such as imidazole, 2,6- lutidine, co||idine, triethylamine, or 1,8—diazabicyclo[5.4.0]undecene (DBU). The reaction can be performed at room temperature or under reflux. The reaction can be performed in the presence of a suitable solvent such as dichloromethane, toluene or ylformamide or a e thereof. The formation of protected estrone silyl ether can also be performed by reaction of a silylating agent such as tert—butyl dimethylsilylchloride, diphenylmethylsilylchloride, dimethylphenylsilylchloride, trimethylsilylchloride, triethylsilylchloride or triisopropylsilylchloride in the presence of a suitable base such as m diisopropylamide (LDA), tert-butyl lithium, sodium or potassium bis(trimethylsilyl)amide (NaHMDS, KHMDS) or lithium tetramethylpiperidine.

Step (b) of the present process comprises reacting the nd of formula (III) in the presence of ium acetate or a derivative thereof such as palladium chloride or Tris(dibenzylideneacetone)dipalladium (Pd2(dba)3), preferably palladium acetate or palladium chloride, more preferably palladium acetate to produce a compound of formula (IV).

In an embodiment, said palladium acetate or a derivative thereof can be present in stoichiometric amounts, or sub-stoichiometric catalytic amounts.

For example the on of step (b) can be performed using stoichiometric s of ium acetate, palladium chloride or Tris(dibenzylideneacetone)dipalladium, preferably stoichiometric amounts of palladium acetate, preferably in a le solvent such acetonitrile, benzonitrile or dimethylsulfoxide, preferably benzonitrile.

This reaction can be performed at room temperature.

In another example, said step (b) can be performed using sub-stoichiometric tic amounts of palladium acetate, palladium chloride, or Tris(dibenzylideneacetone)dipalladium, preferably sub-stoichiometric catalytic amounts of palladium acetate, in the presence of a C1-6alkylene ate such as allyl carbonate and in the presence of an organotin compound as catalyst. Preferably, the organotin compound is tri-butyltin methoxide. Preferably the C1_6alkylene carbonate is allyl methyl carbonate. The reaction can be performed under reflux conditions, optionally under inert atmosphere such as nitrogen or argon atmosphere.

In another example, said step (b) can be performed using sub-stoichiometric catalytic amounts of palladium acetate under an oxygen atmosphere. In r e, said step (b) can be performed using sub-stoichiometric catalytic amounts of palladium chloride, under an oxygen here. In another example, said step (b) can be performed using sub-stoichiometric catalytic amounts of Tris(dibenzylideneacetone)dipalladium, under an oxygen atmosphere.

Preferably, said oxygen atmosphere is pure lar oxygen or atmospheric oxygen (air or circulating air, or renewable air). ably, in step (b) the amount of palladium acetate, palladium chloride or ibenzylideneacetone)dipalladium is at most 0.50 equivalents, preferably at most 0.40 lents, more preferably at most 0.30 equivalents, yet more preferably at most 0.2 equivalents, yet more preferably at most 0.10 equivalents, yet more preferably at most 0.05 equivalents, yet more preferably at most 0.03 equivalents per equivalent of compound of formula (III).

In a preferred embodiment, step (b) is performed with at most 0.10 equivalents of palladium acetate, preferably at most 0.05 equivalents, preferably at most 0.03 equivalents per equivalent of compound of formula (III), in the presence of pure lar oxygen or atmospheric oxygen.

The next step in the process ses the reduction of the compound of formula (IV) with a reducing agent to produce compound of formula (I). Preferably, said reducing agent is a metal hydride nd. For example, the metal hydride compound can be selected from the group comprising LiAIH4, NaBH4, NaBH(OAc)3, ZnBH4, and NaBH4/CeCI3. preferably, said reducing agent is NaBH4/CeCI3_ For example said reduction can be performed in a suitable solvent or a mixture thereof, such as in tetrahydrofuran, or a mixture of methanol and tetrahydrofuran. The reaction can be performed at low atures such as below 15°C, for example below 10°C.

In an embodiment, compound of formula (IV) is not ed but directly d to the alcohol using said reducing agent. In this embodiment, step (b) and (c) are performed in one pot. This one-pot/two-step procedure is the shortest chemical pathway described to obtain compound of formula (I).

WO 64096 This process offers the advantages that the 17-hydroxy function of the nd of formula (I) could be also protected by a protecting group such as an acyl group, more preferably an acetyl group which could be removed in the same time that the 3-protecting group such as 3-acetyl, preferably 3-acetoxy group offering a never described synthesis of estetrol in 6 steps. The roxy function of the nd of formula (I) could be also protected by a silyl group, which could be removed in the same time that the 3-silyl protecting group offering a never described synthesis of estetrol in 6 steps.

According to another embodiment, step (a) can be performed in two steps and comprises the steps of (a1) protecting the hydroxyl of compound of formula (II) using a ting agent to produce a compound of formula (Ila), wherein P1 RZ'Si-RsR“; and (Ila) (a2) converting the ketone of nd of formula (Ila) to its enol ether in the presence of an acylating agent to produce a compound of formula (III).

According to this embodiment, the process for the preparation of 3-P1-estra 1, 3, 5(10),15- tetraeneol of formula (I) from estrone of formula (II) can be preformed as shown in Scheme 2. ("l (Ila) 3 R2 I Rhea R/ ‘o (la) Scheme 2 In this embodiment, rated in Scheme 2, wherein P1 independently RZ'Si-R3R4, and P2 is CO-R1, estrone of formula (II) is reacted with a silylating agent to produce compound of a (Ila). The silylating agent can be selected from the group comprising C1-5alkylsilyl chloride, silyl chloride, C1_6alkylphenylsilyl de; each group being optionally substituted by one or more substituents independently selected from fluoro or C1_4alkyl.

For example, ion of protected estrone silyl ether can be performed by reaction of a silylating agent such as terf-butyl dimethylsilylchloride, diphenylmethylsilylchloride, dimethylphenylsilylchloride, trimethylsilylchloride, triethylsilylchloride, or triisopropylsilylchloride. The reaction can be performed in the presence of a base such as imidazole, 2,6-lutidine, collidine, triethylamine, or 1,8—diazabicyclo[5.4.0]undecene (DBU).

The next step comprises, converting the ketone of compound of formula (Ila) in the presence of an acylating agent to produce a compound of formula (II) wherein P2 is acyl (compound of formula (|||a)). Suitable acylating agents and conditions are as described herein above.

The next step in the process of scheme 2 comprises reacting the nd of formula (Illa) in the presence of palladium acetate or a derivative thereof such as palladium chloride or Tris(dibenzylideneacetone)dipa||adium (Pd2(dba)3) to produce compound of formula (IV) wherein P1 is RZ'Si-R3R4 (compound of formula (|Va)). This reaction can be performed as described herein above.

The next step in the process comprises the reduction of the compound of formula (IVa) with a reducing agent to produce compound of formula (I) wherein P1 is RZ'Si-RsR4 und of formula (Ia)). This on can be performed as described herein above.

The processes according to the present invention have the advantage that the protective group can be removed in situ at the end of the synthesis by conventional methods such as removal of silyl protecting group with fluoride ions, such as tetra-n-butylammonium fluoride; as described in Coppola,G.M. Org Prep Proced, 2007, 39 (2),199-292 hereby incorporated by reference; or removal of si|y| protecting groups using 2,3-dichloro-5,6- dicyano-p-benzoquinone as described in ra, K. J Chem Soc, Perkin Trans 1 1992, (22), 2997-2998; hereby incorporated by nce.

The present s has the age that 3-P1-oxy-estra1,3,5(10),15-tetraenol of formula (I), and subsequently estetrol, can be obtained from e in a reduced number of steps compared to prior art processes, which is more convenient for an economical and industrial synthesis.

The present ion also encompasses a process for the preparation of estetrol, said process comprising preparing a compound of formula (I) using the process of the ion and further reacting compound of formula (I) to produce estetrol.

The t ion also encompasses the use of estetrol directly obtained by the process the ion for the manufacture of a pharmaceutical composition, ably for use in a method selected from a method of hormone replacement therapy, a method of treating vaginal dryness, a method of contraception, a method of enhancing libido, of method of treating skin, a method of promoting wound healing, and a method of treating or preventing a er selected from the group consisting of autoimmune diseases, breast tumors and colorectal tumors.

The invention is illustrated but not limited by the following examples.

EXAMPLES Example 1: Preparation of a compound of formula (I) wherein P1 is acetyl according to an embodiment of the invention.

Step 1: Estra-1, 3, 5 (10), 16-tetraene-3, 17-diol, iacetate 100g of 3-hydroxy-estra-1, 3, 5(10)—trienone (0.370 mole) was poured in 500ml of isopropenyl acetate and 10g of para-toluene-sulfonic acid. The mixture was refluxed.

Acetone and isopropenyl acetate was continuously led off until the temperature d 98°C. Then the mixture was cooled to 0°C and K2C03 was added.

After one hour at 0°C the mixture was filtered, the resulting solution was concentrated and diisopropyl ether added. The precipitate was collected by filtration and dried. It weighted 111.59 (yield: 85%) 1HNMR (CDCI3) 6 0.90 (s,3H, CH3 at C-18),1.30-1.50 (m, 11H), 2.20 (s, 3H, CH3 e), 2.30 CH3 acetate), 2.30-2.50 (m, 2H), 5.54 (broad s,1H)), 6.80 (broad s, 1H, H4), 6.82 (dd, 1H, H2), 7.27 (d, 1H, H1) mp =148.3°C Step 2: 3-acetoxy-estra-1, 3, 5 (10), 15-tetraenone To a solution of 115.59 (0.315 mole) of estra-1,3,5 etraene-3,17-diol, 3,17, diacetate in 1500 ml of acetonitrile were added 3049 (0.095mole) of tri-n-butyltin methoxyde and 11.29 (0.05 mole) of palladium (ll) acetate and allyl methyl carbonate 20 ml. The mixture was refluxed for 2 hours then cooled to room temperature and filtered through a pad of silica gel. The reaction was then diluted with water and extracted with ethyl acetate. After concentration to one third of the l volume diisopropyl ether 1000m| was slowly added.

The precipitate was collected by filtration, washed with diisopropyl ether and used in the next step without further purification. 1HNMR (CDCI3) 6 1.10 (s, 3H, CH3 at C-18), 1.30-2.60 (m, 9H), 2.30 (s, 3H,CH3 3- acetate), 2.90-3.00 (m, 2H), 6.00-6.15 (m, 1H, H15), 6.80 (broad s, 1H, H4), 6.85 (dd, 1H, H2), 7.29 (d, 1H, H1), 7.60 (d, 1H, H16), mp: 177.7°c Step 3: 3-acetoxy-estra-1, 3, 5 (10), 15-tetraeneol The collected material was dissolved in tetrahydrofuran (THF) 300ml and a solution of cerium chloride heptahydrate (123g, 0.33mole) in methanol (300ml) was added. The mixture was cooled to 0°C and sodium dride , 0.47 mole, 1.5q) was added portion wise keeping the temperature below 5°C. At this end of the on, the mixture was stirred for one hour then quenched by addition of a 2N HCI solution (100ml). The solution was partly evaporated in situ and water (4L) was added. The precipitate was collected by tion and dried. After crystallization form a mixture of l propy| ether 3-acetoxy-estra-1, 3, 5(10),15-tetraeneol was isolated in 75 % yield. 1HNMR (CDCI3) 6 0.85 (s, 3H, CH3 at C-18), 1.20-2.50 (m, 8H), 2.30 (s, 3H,CH3 3- acetate), 2.80-3.05 (m, 2H), 4.40 (broad s, 1H, H17), 5.75 (broad s, 1H), 6.04 (broad s, 1H), 6.80 (broad s, 1H, H4), 6.84 (broad s, 1H, H2), 7.29 (d, 1H, H1), mp: 120.7°C e 2: Preparation of a compound of formula (I) wherein P1 is t-butyldimethylsilyl according to an embodiment of the invention.

Step 1: 3,17-di-t-butyldimethylsiloxy-estra-1, 3, 5(10)tetraeneol To a solution of estrone (509, 0.185 mole) and 2,6-lutidine (62g, 0.58 mole) in dichloromethane 400ml was added drop wise t-butyl-dimethylsilyl-triflate g,0.39 mole).The solution was stirred at room temperature for 6 hours. Water (300ml) was added and the organic layer was washed with a diluted solution of sodium carbonate. The dichloromethane solution was partially evaporated and ethyl acetate was added.

Diisopropyl ether was added to this solution. The mixture was stirred for 2 hours at 0°C.

The itate was ted by filtration and dried. 83 g of the title compound were obtained (90% yield). 1HNMR ) 5 0.20 (s, 12H, (CH3)2-Si-), 0.90 (s, 3H, CH3 at C-18), 0.95 (s, 9H, (CH3)3- C-Si-), 1.00 (s, 9H, (CH3)3-C-Si-), 1.20-2.40 (m, 11H), 2.75-2.95 (m, 2H), 4.48 (m, 1H, H16), 6.58 (broad s, 1H, H4), 6.62 (dd, 1H, H2), 7.12 (d, 1H, H1), mp: 976°C Step 2: 3-t-butyldimethylsiloxy-estra-1, 3, 5 (10)tetraeneone To a solution of 3, 17-di-t-butyldimethylsiloxy-estra-1, 3, 5(10)—16-tetraeneol 83 g (0.166 mole) in 400ml of acetonitrile was added Pd(OAc)2 3.8 g (0.017 mole) in an oxygen atmosphere. The mixture was stirred at 40°C for 12 hours then filtered through a pad of celite. A diluted solution of sodium carbonate was added and the mixture was extracted with ethyl acetate.

WO 64096 After tration, ropyl ether was added and the mixture was stirred at 0°C for one hour. The product (5479, 86% yield) was collected by filtration and used in the next step without further purification. 1HNMR (CDCI3) 6 0.20 (s, 6H, (CH3)2-Si-), 1.00 (s, 9H, (CH3)3-C-Si-), 1.13 (s, 3H, CH3 at C-18), 1.20-2.70 (m, 11H), 2.80-3.00 (m, 2H), 6.10 (dd, 1H, H15), 6.58 (broad s, 1H, H4), 6.62 (dd, 1H, H2), 7.11 (d, 1H, H1), 7.63 (dd, 1H, H16), mp: 165°C Step 3: 3 y|dimethylsiloxy-estra-1, 3, 5 (10)tetraeneol The collected material , 0.143 mole) was dissolved in THF 300ml and a solution of cerium chloride heptahydrate (53.39, 0.143 mole) in methanol (300ml) was added. The mixture was cooled to 0°C sodium borohydride (8.129, 0.213 mole, 1.5eq) was added portion wise keeping the temperature below 9°C. At this end of the addition the mixture was stored for one hour then quenched by addition of a 2N HCI solution (100ml). The solution was partly evaporated in situ and water (4L) was added. The precipitate was collected by filtration and dried. After crystallization from a mixture of ethanol propy| ether the product was collected by filtration and dried. lt weighted 46.6g (85% yield). 1HNMR (CDCI3) 6 0.20 (s, 6H, (CH3)2-Si-), 0.89 (s, 3H, CH3 at C-18), 1.00 (s, 9H, (CH3)3- C-Si-), 1.20-2.40 (m, 10H), 2.75-2.95 (m, 2H), 4.40 (broad s, 1H, H17), 5.65-5.75 (m, 1H), .95-6.10 (m, 1H), 6.57 (broad s, 1H, H4), 6.60 (dd, 1H, H2), 7.13 (d, 1H, H1) mp: 107.5°c Example 3: Preparation of a compound of formula (I) wherein P1 is t-butyldimethylsilyl according to an embodiment of the invention.

Step 1: 3 -t-buty|dimethylsiloxy-estra-1, 3, 5(10) eone To a solution of estrone (1009, 0.37 mole) in 400ml of dichloromethane, imidazole (50.36g, 0.74 mole) and t-butyl-dimethylsilyl chloride (61.3g,0.41 mole) were added The solution was stirred at room temperature for 24 hours. Then water (200ml) was added.

The c layer was partially evaporated and diisopropyl ether added. The white solid formed was collected by filtration and dried. lt ed , yield 95%, mp 172°C. 1HNMR (CDCI3) 6 0.20 (s, 6H, (CH3)2-Si-), 0.90 (s, 3H, CH3 at C-18), 1.00 (s, 9H, (CH3)3- C-Si-), 1.20-2.60 (m, 13H), 2.75-2.95 (m, 2H), 5.65-5.75 (m, 1H), 6.58 (broad s, 1H, H4), 6.63 (dd, 1H, H2), 7.12 (d, 1H, H1) mp: 171.6°C Step 2: 3 yldimethylsiloxy-estra-1, 3, 5(10) tetraeneacetate 3 -t-butyldimethylsiloxy-estra-1, 3, 5(10) -trieneone 1359 (0.351 mole) were poured in 600ml of isopropenyl acetate and 12 9 of para-toluene-sulfonic acid. The mixture was refluxed. Acetone and isopropenyl acetate were continuously distilled off until the internal temperature reached 98°C. Then the mixture was cooled to 0°C and potassium carbonate added. After one hour at 0°C the mixture was filtered. The resulting solution was partially concentrated and diisopropyl ether added. The precipitate was collected by filtration and crystallized from a mixture of ethyl acetate and e. The product was collected by filtration and dried. lt weighted 119.59 (yield 80%).

Step 3: 3 -t-butyldimethylsiloxy-estra-1, 3, 5 (10)tetraeneone To a solution of 3 -t-butyldimethylsiloxy-estra-1, 3, 5(10) tetraeneacetate 119.59 (0.280 mole) in acetonitrile l) were added 27.29 (0.085 mole of tributyltin methoxide, 11.2 9 (0.05 mole) of palladium acetate and 64 ml(0.560 mole) of allyl methyl carbonate. The mixture was refluxed for 2 hours then cooled to room temperature and filtered through a pad of silica gel. The e was diluted with water and extracted with ethyl acetate. After concentration to one third of the initial volume diisopropyl ether was added and the solution cooled at 0°C for one hour.

The t was collected by filtration. lt ed 919 (85% yield) and was used in the next step t further purification. 1HNMR (coc13) 5 0.20 (s, 6H, (CH3)2-Si-), 1.00 (s, 9H, (CH3)3-C-Si-), 1.13 (s, 3H, CH3 at C-18), 1.20-2.70 (m, 11H), 2.80-3.00 (m, 2H), 6.10 (dd, 1H, H15), 6.58 (broad s, 1H, H4), 6.62 (dd, 1H, H2), 7.11 (d, 1H, H1), 7.63 (dd, 1H, H16), mp: 165°C Step 4: 3 -t-butyldimethylsiloxy-estra-1, 3, 5 (10)tetraeneol The reduction step was performed as described in step 3 of example 2: the collected material was dissolved in THF and a solution of cerium chloride heptahydrate (1 eq) in methanol was added. The mixture was cooled to 0°C sodium borohydride (1.5eq) was added n wise keeping the temperature below 9°C. At this end of the addition the e was stored for one hour then quenched by addition of a 2N HCI solution. The solution was partly evaporated in situ and water was added. The precipitate was collected by filtration and dried. After crystallization from a e of l /diisopropy| ether the product was collected by filtration and dried. 2012/060447 1HNMR (CDCI3) 6 0.20 (s, 6H, (CH3)2-Si-), 0.89 (s, 3H, CH3 at C-18), 1.00 (s, 9H, (CH3)3- , .40 (m, 10H), 2.75-2.95 (m, 2H), 4.40 (broad s, 1H, H17), 5.65-5.75 (m, 1H), .95-6.10 (m, 1H), 6.57 (broad s, 1H, H4), 6.60 (dd, 1H, H2), 7.13 (d, 1H, H1) mp: 107.5°c Example 4: Step 2 of Example 1 was repeated using different reagent and reactions conditions as listed in Table 1. 3-acetoxy-estra-1, 3, 5 (10), raenone was obtained. The yields and conversion rates are given in Table 1.

Table 1 on Conversion rate Isolated Yield Pd(OAc)2 Other reagents conditions THF,ACN, Allylmethyl carbonate (1,8 6(1) ACN 70 C z 70 tributyltin ’ methoxide (0,3 6(1) ACN, THF, DMSO, 80°C DMSO,CH2CI2, THF: tetrahydrofuran; ACN acetonitrile; RT: room temperature; DMSO: dimethylsulfoxide; ND not determined.

Example 5: Step 2 of Example 2 was repeated using different reagent and reactions conditions as listed in Table 2. tyldimethylsiloxy-estra-1, 3, 5 (10)—15-tetraeneone was obtained. The yields and conversion rates are given in Table 2.

Table 2 Other Reaction Conversion rate Isolated Yield Pd(0Ac)2 reagents conditions (%) (%) —— THF, RT ”-— DMSO,CHzCI2, 35°C THF: tetrahydrofuran; ACN acetonitrile; RT: room temperature; DMSO: dimethylsulfoxide; ND not determined.

It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments ing to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention.

Claims (14)

1. A process for the preparation of a compound of a (I) said process comprising the steps of a) reacting a compound of formula (II), with an acylating or a silylating agent to produce a compound of formula (III), wherein P1 and P2 are each independently a protecting group selected from R2-Si-R3R4, or R1CO-, n R1 is a group selected from the list consisting of C1-6alkyl, C3-6cycloalkyl, tuted C1-6alkyl and substituted C3-6cycloalkyl where the substituted groups are tuted by one or more substituents independently selected from fluoro or C1-4alkyl; R2, R3 and R4 are each a group independently selected from the list consisting of C1-6alkyl, phenyl, substituted C1-6alkyl and substituted phenyl where the substituted groups are substituted by one or more substituents independently selected from fluoro or C1-4alkyl; (II) (III) b) reacting the compound of formula (III) in the presence of palladium acetate or palladium chloride to produce compound of formula (IV); and (IV) c) reacting the compound of formula (IV) with a reducing agent to produce compound of formula (I).

2. The process ing to claim 1, wherein P1 is R1CO-.

3. The process according to claim 1, wherein P1 is R2-Si-R3R4.

4. The process according to claim 3, wherein P2 is R2-Si-R3R4.

5. The process according to any one of claims 1 to 3, n P2 is R1CO-.

6. The process according to claim 5, wherein step (a) comprises the steps of (a1) protecting the yl of compound of formula (II) with a ting agent to produce a compound of formula (IIa), n P1 has the same meaning as that defined in claim 3; and (IIa) (a2) protecting the ketone of compound of formula (IIa) in the presence of an acylating agent to produce compound of formula (III).

7. Process according to any one of claims 1 to 3, 5, and 6 wherein the acylating agent is C2-6alkenylC1-6alkanoate or C2-6alkenylC3-6cycloalkanoate.

8. Process according to any one of claims 1, 3 to 7, wherein the silylating agent is selected from the list comprising C1-6alkylsilylchloride, C1-6alkylsilyltriflate, phenylsilyl de, silyltriflate, C1-6alkylphenylsilylchloride, kylphenylsilyltriflate, substituted C1-6alkylsilylchloride, substituted C1-6alkylsilyltriflate, substituted phenylsilyl chloride, substituted silyltriflate, substituted C1-6alkylphenylsilylchloride and substituted C1-6alkylphenylsilyltriflate, where the substituted groups are substituted by one or more substituents independently selected from fluoro or C1-4alkyl.

9. The process according to any one of claims 1 to 8, wherein step (b) is performed in the presence of a C1-6alkylene carbonate and an organotin compound.

10. The process according to any one of claims 1 to 9, wherein said palladium e or palladium chloride is present in stoichiometric amounts.

11. The process according to any one of claims 1 to 9, wherein said reaction is performed with palladium e or palladium de present in catalytic or substoichiometric amounts, preferably the reaction is med in an oxygen atmosphere.

12. The process according to any one of claims 1 to 11, wherein the reducing agent in step (c) is selected from the group of metal hydride compounds.

13. The process according to claim 12, wherein the metal e compound is selected from the group comprising NaBH4/CeCl3, LiAlH4, NaBH4, NaBH(OAc)3, and ZnBH4.

14. Process for the ation of estetrol, said process comprising the steps of (i) preparing a compound of formula (I) by a process according to any one of claims 1 to 13 and (ii) further reacting compound of formula (I) to produce estetrol.