WO2001055091A1

WO2001055091A1 - Solid-supported process for making n-substituted peptide mimetic compounds

Info

Publication number: WO2001055091A1
Application number: PCT/US2001/002467
Authority: WO
Inventors: Sean Rees Klopfenstein; Adam Golebiowski; Min Li
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2000-01-25
Filing date: 2001-01-25
Publication date: 2001-08-02
Anticipated expiration: 2002-07-25
Also published as: AU2001234560A1

Abstract

The subject invention involves processes for making N-substituted peptide mimetic compounds comprising a Petasis reaction scheme using reactants comprising an activated carbonyl compound, an amine compound, and a boronic acid compound, and libraries of such compounds.

Description

SOLID-SUPPORTED PROCESS FOR MAKING N-SUBSTITUTED PEPTIDE MIMETIC COMPOUNDS

CROSS REFERENCE

This application claims priority under Title 35, Umted States Code 119(e) from Provisional Application Serial No 60/177,841, filed January 25, 2000

FIELD OF THE INVENTION

The subject invention involves processes for making N-substituted peptide mimetic compounds usmg a solid-phase Petasis reaction

BACKGROUND OF THE INVENTION

The mteraction of peptides and proteins with macromolecular receptors is responsible for the initiation of most biological processes Unfortunately, these biomolecules have severe limitations as orally available therapeutics due to their large size, and the susceptibility of the peptide bond to degradation The ability to mimic these large biomolecules with small molecules has become the "Holy Grail" in drug discovery The advent of combmatonal chemistry and solid phase synthesis has helped to fuel this effort There have been numerous reports on the synthesis of constrained as well as linear peptide mimetics

SUMMARY OF THE INVENTION

The subject mvention involves processes for making N-substituted peptide mimetic compounds compnsmg a Petasis reaction scheme using reactants compπsmg an activated carbonyl compound, an amine compound, and a boronic acid compound, and libraries of such compounds DETAILED DESCRIPTION OF THE INVENTION

As used herein unless specified otherwise, "alkyl" means a hydrocarbon chain which is branched, lmear or cyclic, saturated or unsaturated (but not aromatic), substituted or unsubstituted The term "alkyl" may be used alone or as part of another word where it may be shortened to "alk" (e g , in alkoxy, alkylacyl) Preferred linear alkyl have from one to about twenty carbon atoms, more preferably from one to about ten carbon atoms, more preferably still from one to about six carbon atoms, still more preferably from one to about four carbon atoms, most preferred are methyl or ethyl Preferred cyclic and branched alkyl have from three to about twenty carbon atoms, more preferably from three to about ten carbon atoms, more preferably still from three to about seven carbon atoms, still more preferably from three to about five carbon atoms Preferred cyclic alkyl have one hydrocarbon ring, but may have two, three, or more, fused or spirocycle hydrocarbon rings. Preferred alkyl are unsaturated with from one to about three double or triple bonds, preferably double bonds; more preferably they are mono-unsaturated with one double bond. Still more preferred alkyl are saturated. Saturated alkyl are referred to herein as "alkanyl". Alkyl unsaturated only with one or more double bonds (no triple bonds) are referred to herein as "alkenyl". Preferred substituents of alkyl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, amide, alkylamide, arylamide, formyl, alkylacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, nitro, and cyano. Also, unsubstituted alkyl are preferred.

As used herein, "heteroatom" means a nitrogen, oxygen, or sulfur atom.

As used herein, "alkylene" means an alkyl which connects two other moieties, "heteroalkylene" means an alkylene having one or more heteroatoms in the connecting chain.

As used herein unless specified otherwise, "aryl" means an aromatic hydrocarbon ring (or fused rings) which is substituted or unsubstituted. The term "aryl" may be used alone or as part of another word (e.g., in aryloxy, arylacyl). Preferred aryl have from six to about fourteen, preferably to about ten, carbon atoms in the aromatic ring(s), and a total of from about six to about twenty, preferably to about twelve, carbon atoms. Preferred aryl is phenyl or naphthyl; most preferred is phenyl. Preferred substituents of aryl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, amide, alkylamide, arylamide, formyl, alkylacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, nitro, and cyano. Also, unsubstituted aryl are preferred.

As used herein unless specified otherwise, "heterocycle" or "heterocyclyl" means a saturated, unsaturated or aromatic cyclic hydrocarbon ring (or fused rings) with one or more heteroatoms in the hydrocarbon ring(s). Preferred heterocyclyls are attached to the other structures at a carbon of the heterocyclyl ring. Preferred heterocycles have from one to about six heteroatoms in the ring(s), more preferably one or two or three heteroatoms in the ring(s). Preferred heterocycles have from three to about fourteen, preferably to about ten, carbon plus heteroatoms in the ring(s), more preferably from three to about seven, more preferably still five or six, carbon plus heteroatoms in the rings(s); and a total of from three to about twenty carbon plus heteroatoms, more preferably from three to about ten, more preferably still five or six, carbon plus heteroatoms. Preferred heterocycles have one ring, but may have two, three, or more, fused or spirocycle rings. More preferred heterocycle rings include those which are one ring with 5 or 6 carbon plus heteroatoms in the ring with one to about three ring heteroatoms, no more than two of which are O and S; and those which are two fused rings with 8-10 carbon plus heteroatoms in the rings with one to about four ring heteroatoms, no more than two of which are 0 and S. Still more preferred are such 5- or 6-ring atom heterocycles with one or two ring atoms being O or S and the others being C; or with one, two or three ring atoms being N and the others being C. Such preferred 5- or 6-ring atom heterocycles are preferably saturated, unsaturated with one or two double bonds, or aromatic. Such preferred 5- or 6-ring atom heterocycles are preferably a single ring; or fused with a 3- to 6- ring atom hydrocarbon ring which is saturated, unsaturated with one double bond, or aromatic (phenyl); or fused with another such 5- or 6-ring atom heterocyclic ring. Heterocycles are unsubstituted or substituted. Preferred heterocycle substituents are the same as for alkyl.

As used herein unless specified otherwise, "heteroaryl" means an aromatic heterocycle.

The subject invention process is a solid-phase route to peptide mimetics utilizing a boronic acid Mannich reaction (Petasis reaction) as the key transformation in the synthesis. The Petasis reaction is a three component condensation reaction among an activated carbonyl, an amine, and a boronic acid. A subject invention process is depicted schematically as follows:

3 4

Commercially available Fmoc protected amino acid resin ester 1 is a preferred starting material for the subject process; in step a), the protecting group is removed. Alternatively, unprotected amino acid resin ester can be prepared using well-known methods.

The amine on the resin is reductively alkylated with an aldehyde R2-CHO and a reducing agent in step b) to provide 2. The secondary amine of 2 is then treated with glyoxylic acid and a boronic acid, R3-B(OH)2 at room temperature in a key carbon-carbon bond forming step c) to produce 3. Appreciable diastereoselectivity does not occur in this step. The reductive alkylation and this Petasis chemistry step do not substantially epimerize (about 10% or less) the α-stereocenter in the resin-bound starting material. Carboxylic acid 3 is reacted with amine R4-NH2 in step d), preferably after treating 3 with diisopropylcarbodiimide/hydroxybenzotriazole (DIC/HOBt). The product 4 is cleaved from the resin in step e), preferably with trifluoroacetic acid/water (TFA/H2O).

In the subject process, Rl is selected from hydrogen, alkyl, aryl, and heterocycle. Preferred Rl is selected from unsubstituted or substituted about Ci -Cg alkyl, phenyl, and naphthyl; preferred substituents of such Rl are selected from amino, alkylamino, arylamino, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, halo, nitro, cyano, carboxy and its esters and amides.

In the subject process, R2 is selected from hydrogen, alkyl, aryl, and heterocycle. Preferred R2 is selected from unsubstituted or substituted about C1 -C1 Q alkyl, phenyl, and naphthyl; preferred substituents of such R2 are selected from amino, alkylamino, arylamino, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, halo, nitro, cyano, carboxy and its esters and amides.

In the subject process, R3 is selected from alkyl, aryl, and heterocycle. Preferred R3 is selected from unsubstituted or substituted phenyl, naphthyl, heteroaryl having one ring or two fused rings, α,β -unsaturated about C2-C1 _Q alkyl, and α,β -unsaturated conjugated phenyl, naphthyl or heteroaryl having one ring or two fused rings; preferred substituents of such R3 are about Ci -Cg alkyl, phenyl, naphthyl, heteroaryl having one ring or two fused rings, amino, alkylamino, arylamino, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, halo, nitro, cyano, carboxy and its esters and amines.

In the subject process, R4 is selected from hydrogen, alkyl, aryl, and heterocycle. Preferred R4 is selected from unsubstituted or substituted about C _j-Ci 2 alkyl, phenyl, and naphthyl; preferred substituents of such R4 are selected from amino, alkylamino, arylamino, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, halo, nitro, cyano, carboxy and its esters and amides.

Non-limiting examples of compounds that are made using the subject process are 4A - 41:

4D 4E 4F

The following is a detailed example for making compound 4A.

Fmoc-glycine loaded Wang resin (1 g; 0.44 mmol/g; Advanced Chemtech) is rinsed three times with dichloromethane (DCM), then treated with a 25% solution of piperidine in drmethylformamide (DMF) for 45 minutes. The resin is filtered and washed several times with DMF then alternating DCM and methanol (MTH) multiple times followed by trimethylorthoformate (TMOF) three times. The resin is swelled in TMOF (10 mL), and to this is added benzaldehyde (0.412 mL, 8 mmol). The resin is agitated for 1 h. The resin is filtered and rinsed three times with TMOF before adding a solution of sodium cyanoborohydride (NaCNBH3)

(0.496 g, 8 mmol.) in 1% acetic acid in TMOF (AcOH/TMOF). The mixture is agitated for 15 minutes, during which time the reaction vessel is periodically vented, filtered and washed multiple times with alternating DCM and MTH. Approximately half of the resin (0.22 mmol) is treated with 95% trifluoroacetic acid in water (TFA/H2O) for 1 h. The resin is filtered and washed several times with MTH. The filtrate and washings are combined and evaporated to dryness. Following co-evaporation of the resulting oil with chloroform (CHL), the product is vacuum dried to yield the following compound as a white solid:

The remaining resin (0.22 mmol) is swelled in DCM (10 mL); to this is added phenylboronic acid (0.244 g, 2 mmol) and glyoxylic acid (0.184 g, 2 mmol). The reaction is agitated for 18 h. at room temperature, filtered and rinsed three times with DCM. This process is repeated for 60 h. The resin is filtered and washed with DCM and MTH several times in an alternating fashion. The resin is swelled in DMF (10 mL); to this is added HOBt (0.306 g, 2 mmol), followed by DIC (0.313 mL, 2 mmol). This reaction mixture is agitated for 1 h. at room temperature before filtering and rinsing three times with DMF. To the resin is added DMF (5 mL) followed by butylamine (0.195 mL, 2 mmol); the reaction is agitated for 16 h. The resin is filtered and washed with copious amounts of DMF followed by alternating DCM/MTH washes. The resin is subjected to a cleavage cocktail of 95% TFA/H2O for 1 h. The resin is filtered and washed several times with MTH. The filtrate and washings are combined and evaporated to dryness. Following co-evaporation of the resulting white oil with CHL, the product is vacuum dried for 60 h. to yield 4A as a white solid. The crude product is purified by reverse phase HPLC to produce 4A as a white solid.

While particular embodiments of the subject invention have been described, it will be obvious to those skilled in the art that various changes in modifications of the subject invention can be made without departing from the spirit and scope of the invention. It is intended to cover, in the appended claims, all such modifications that are within the scope of this invention.

Claims

WHAT IS CLAIMED IS:

1. A process for making N-substituted peptide mimetic compounds comprising a Petasis reaction scheme using reactants comprising an activated carbonyl compound, an amine compound, and a boronic acid compound.

2. The process of Claim 1 characterized in that the carbonyl compound is R2-CHO, characterized in that R2 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle; the boronic acid compound is R3-B(OH)2, characterized in that R3 is selected from the group consisting of alkyl, aryl, and heterocycle; and the amine compound is R4- NH2, characterized in that R4 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle.

3. The process of Claim 3 characterized in that R2 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 10 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl; R3 is selected from the group consisting of unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl, unsubstituted or substituted heteroaryl having one ring or two fused rings, unsubstituted or substituted α,β-unsaturated alkyl having from 2 to 10 carbon atoms, and unsubstituted or substituted α,β -unsaturated phenyl, naphthyl, or heteroaryl having one ring or two fused rings; and R4 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 12 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl.

4. A process for making N-substituted peptide mimetic compound comprising the following steps: b) reacting an amino acid resin ester:

characterized in that Rl is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle, with an aldehyde: R2-CHO, characterized in that R2 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle, and a reducing agent to provide a secondary amine:

c) treating the secondary amine from step b) with glyoxylic acid and a boronic acid: R3- B(OH)2, characterized in that R3 is selected from the group consisting of alkyl, aryl, and heterocycle, to provide a carboxylic acid:

R2 0 ( 0

R1 ^{R3 H} d) reacting the carboxylic acid from step c) with an amine R4-NH2, characterized in that R4 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle, to provide a resin-bound N-alkylated peptide mimetic compound:

5. The process of Claim 4 characterized in that the reducing agent in step b) is cyanoborohydride .

6. The process of Claim 5 characterized in that in step d), prior to addition of the amine, the carboxylic acid is treated with diisopropylcarbodiimide and hydroxybenzotriazole.

7. The process of Claim 4 characterized in that Rl is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 6 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl; R2 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 10 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl; R3 is selected from the group consisting of unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl, unsubstituted or substituted heteroaryl having one ring or two fused rings, unsubstituted or unsubstituted α,β -unsaturated alkyl having from 2 to 10 carbon atoms, and unsubstituted or substituted α,β -unsaturated phenyl, naphthyl, or heteroaryl having one ring or two fused rings; and R4 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 12 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl.

8. The process of Claim 7 characterized in that the reducing agent in step b) is cyanoborohydride .

9. The process of Claim 8 characterized in that in step d), prior to addition of the arnine, the carboxylic acid is treated with diisopropylcarbodiimide and hydroxybenzotriazole.

10. The process of Claim 4 comprising an additional step: e) cleaving from the resin-bound mimetic compound of step d), N-substituted peptide mimetic compound:

by treating the resin-bound compound with trifluoroacetic acid/water.

11. The process of Claim 10 comprising an additional step: a) deprotecting N-protected amino acid resin ester.

12. The process of Claim 11 characterized in that the reducing agent in step b) is cyanoborohydride.

13. The process of Claim 12 characterized in that in step d), prior to addition of the amine, the carboxylic acid is treated with diisopropylcarbodiimide and hydroxybenzotriazole.

14. The process of Claim 9 comprising an additional step: e) cleaving from the resin-bound mimetic compound of step d), N-substituted peptide mimetic compound:

by treating the resin-bound compound with trifluoroacetic acid/water.

15. A library of compounds having the structure:

characterized in that Rl is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle; R2 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle; R3 is selected from the group consisting of alkyl, aryl, and heterocycle; and R4 is selected from the group consisting of hydrogen, alkyl, aryl, and heterocycle.

16. The library of Claim 15 characterized in that Rl is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 6 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl; R2 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 10 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl; R3 is selected from the group consisting of unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl, unsubstituted or substituted heteroaryl having one ring or two fused rings, unsubstituted or substituted α,β -unsaturated alkyl having from 2 to 10 carbon atoms, and unsubstituted or substituted α,β -unsaturated phenyl, naphthyl, or heteroaryl having one ring or two fused rings; and R4 is selected from the group consisting of unsubstituted or substituted alkyl having from 1 to 12 carbon atoms, unsubstituted or substituted phenyl, and unsubstituted or substituted naphthyl.