Process for preparing an optically pure intermediate for a phosphonosulfonate soualene synthetase inhibitor

Abstract

A process is provided for preparing a substantially optically pure phosphonate ester or phosphonate thioester intermediate via an enzymatically catalyzed enantioselective reaction, which intermediate is employed in preparing phosphonosulfonate squalene synthetase inhibitors.

What we claim is: 
     
       1. A method for preparing a substantially optically pure phosphonate of the structure ##STR34## wherein R 1  is a lipophilic group containing at least 7 carbons; R 3  is alkyl, cycloalkyl, aryl or arylalkyl; which comprises reacting a racemic phosphonate of the structure ##STR35## wherein R 1  is as defined above, with an ester of the structure ##STR36## wherein R 3  is as defined above; and   OR 2  represents a leaving group and R 2  is alkyl, aryl, arylalkyl or alkenyl, in the presence of an enzyme or microorganism which is a source for enzyme capable of catalyzing trans- esterification of an alcohol, to form the substantially optically pure phosphonate, and recovering the substantially optically pure phosphonate.   
     
     
       2. The process as defined in claim 1 wherein the microorganism employed as a source for enzyme is of the genus Mucor, Escherichia, Staphylococcus, Agrobacterium, Rhizopus, Aspergillus, Nocardia, Streptomyces, Trichoderma, Candida, Rhodotorula, Torulopsis, Humicola, Kibdelosporangium, Bacillus, Alcaligenes, Pseudomonas, Brevibacterium, Enterobacter, Chromobacterium, Arthrobacter, Microbacterium, Mycobacterium, Saccharomyces, Penicillium, Chaetomium, Cladosporium or Geotrichum. 
     
     
       3. The process as defined in claim 2 wherein the enzyme employed is Candida cylindracea, Pseudomonas fluorescens, Rhizopus niveus, Penicillium sp., Rhizopus oryzae, Aspergillus niger, Mucor meihei, Geotrichum candidum, porcine pancreas, wheat germ, Chromobacterium viscosum, Novo Lipolase, Pseudomonas lipase, esterase, α-chymotrypin and pancreatin. 
     
     
       4. The process as defined in claim 1 wherein the microorganism employed is Pseudomonas fluorescens, Pseudomonas putida, Escherichia coli, Staphylococcus aureus, Geotrichum candidum, Alcaligenes faecalis, Steptomyces griseus, Streptomyces clavuligerus, Nocardia erthropolis, Nocardia asteroides, Mycobacterium phlei, Agrobacterium radiobacter, Aspergillus niger, Rhizopus oryzae or Esterase 30000 enzyme. 
     
     
       5. The process as defined in claim 1 where in the starting racemic phosphonate R 1  is alkyl containing 7 to 25 carbons in the chain; alkenyl containing from 7 to 25 carbon atoms in the chain and from 1 to 6 double bonds; alkynyl containing from 7 to 25 carbons on the chain and from 1 to 6 triple bonds; mixed alkenyl-alkynyl containing 1 to 5 double bonds and 1 to 5 triple bonds; or aryl; and where in the above groups alkenyl, alkynyl and/or aryl may be substituted or unsubstituted; cycloheteroalkyl linked through a carbon on the ring or a heteroatom; cycloalkyl; heteroarylalkyl; cycloalkylalkyl; heteroaryl; cycloheteroalkylalkyl; or a group of the structure ##STR37## wherein Ar is aryl or heteroaryl, and Ar may include one to three additional rings fused to Ar, and wherein (CH 2 ) p  contains from 1 to 15 carbons in the chain and may include 0, 1, 2 or 3 double bonds and/or 0, 1, 2 or 3 triple bonds in the normal chain, and may contain an ether or amino function in the chain, and/or may include 0, 1, 2 or 3 substituents as defined below for R 6  ; and R 6 , R 7 , R 8  and R 8a  are the same or different and are H, alkyl containing 1 to 40 carbons, alkoxy containing 1 to 40 carbons, alkenyl containing 2 to 40 carbons, alkenyloxy containing 2 to 40 carbons, alkynyl containing 2 to 40 carbons, alkynyloxy containing 2 to 40 carbons, hydroxy, halogen, nitro, amino, thiol, alkylthio, alkyl-sulfinyl, alkylsulfonyl, carboxy, alkoxycarbonyl, aminocarbonyl, alkyl-carbonyloxy, alkylcarbonyl-amino, cycloheteroalkyl, cycloheteroalkylalkyl, heteroaryl, cycloalkyl, cycloalkylalkyl, Ar-alkyl, ArO, Ar-amino, Ar, Ar-thio, Ar-sulfinyl, Ar-sulfonyl, cyano, Ar-carbonyloxy, or Ar-carbonylamino. 
     
     
       6. The process as defined in claim 1 wherein the starting racemic phosphonate R 1  is Ar 1  --O--Ar 2  -(CH 2 ) p  --wherein Ar 1  is an aryl group and Ar 2  is an aryl group, and p is 1 to 15. 
     
     
       7. The process as defined in claim 6 wherein the starting racemic phosphonate Ar 1  --O--Ar 2  --(CH 2 ) p  --is ##STR38## where n is 2, 3 or 4. 
     
     
       8. The process as defined in claim 1 wherein the starting racemic phosphonate is ##STR39## and the product is ##STR40## 
     
     
       9. The process as defined in claim 1 wherein the reaction of the racemic phosphonate and enzyme or microorganism is carried out at a temperature within the range of from about 15° to about 60° C., in the presence of an ester source of the structure R 3  COOR 2 . 
     
     
       10. The process as defined in claim 9 wherein the inert organic solvent is toluene, hexane, or t-butylmethyl ether and the ester source is isopropenyl acetate, trifluoroethyl butyrate, vinyl butyrate or vinyl acetate. 
     
     
       11. A process for preparing a substantially optically pure phosphonate thioester of the structure ##STR41## wherein R 9  is alkyl' R 1  is a lipophilic group containing at least 7 carbons; which comprises treating a racemic phosphonate thioester of the structure ##STR42## wherein R 1  is as defined above, and     R 9  is alkyl; with an enzyme or microorganism which is a source of enzyme capable of stereoselectively hydrolyzing the thioester bond to form the substantially optically pure phosphonate thioester, and recovering the substantially pure phosphonate thioester.   
     
     
       12. The process as defined in claim 11 wherein the microorganism employed as a source for enzyme is of the genus Mucor, Escherichia, Staphylococcus, Agrobacterium, Rhizopus, Aspergillus, Nocardia, Streptomyces, Trichoderma, Candida, Rhodotorula, Torulopsis, Humicola, Kibdelosporangium, Bacillus, Alcaligenes, Pseudomonas, Brevebacterium, Enterobacter, Chromobacterium, Arthrobacter, Microbacterium, Mycobacterium, Saccharomyces, Penicillium, Chaetomium, Cladosporium or Geotrichum. 
     
     
       13. The process as defined in claim 12 wherein the enzyme employed is Candida cylindracea, Pseudomonas fluorescens, Rhizopus niveus, Penicillium sp., Rhizopus oryzae, Aspergillus niger, Mucor meihei, Geotrichum candidum, porcine pancreas, wheat germ, Chromobacterium viscosum, Novo Lipolase, and Pseudomonas lipase, esterase, α-chymotrypin and pancreatin. 
     
     
       14. The process as defined in claim 13 wherein the microorganism employed is Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas ovalis, Escherichia coli, Staphylococcus aureus, Geotrichum candidum, Alcaligenes faecalis, Steptomyces griseus, Streptomyces clavuligerus, Nocardia erthropolis, Nocardia asteraides, Mycobacterium phlei, Agrobacterium radiobacter, Aspergillus niger, Rhizopus oryzae or Esterase 30000 enzyme. 
     
     
       15. The process as defined in claim 11 where in the starting racemic thioester R 1  is Ar 1  --O--Ar 2  --(CH 2 ) p  --wherein Ar 1  is an aryl group and Ar 2  is an aryl group, and p is 1 to 15. 
     
     
       16. The process as defined in claim 11 wherein the starting racemic phosphonate is ##STR43## and the product is ##STR44## 
     
     
       17. A process for preparing a phosphono-sulfonate of the structure ##STR45## wherein R 1  is a lipophilic group containing at least 7 carbons; R 5  is H, alkyl, arylalkyl, aryl or cycloalkyl; or a metal ion or other pharmaceutically acceptable salt, or prodrug ester; R 5a  is H, alkyl, arylalkyl, aryl or cycloalkyl, or a metal ion or other pharmaceutically acceptable salt, or prodrug ester;   which comprises   providing a substantially optically pure phosphonate thioester of the structure ##STR46## wherein R 1  and R 5  are as defined above and R 9  is alkyl, and employing the thioester to form the phosphonosulfonate.