Process for the preparation of propionic acid derivatives

Abstract

The invention relates to a process for the preparation of a compound of formula (I) or a salt thereof.

1 . A process for the preparation of a compound of formula (I) 
       
         
           
           
               
               
           
         
         or a salt thereof, wherein a compound of formula (II) 
       
       
         
           
           
               
               
           
         
         or a salt thereof is hydrogenated 
         in the presence of a catalyst comprising iridium and a compound of formula (III), 
       
       
         
           
           
               
               
           
         
         R 1  is selected from the group consisting of: hydrogen, alkyl, aryl and arylalkyl; and 
         R 2  is aryl. 
       
     
     
         2 . A process according to  claim 1 , wherein R 1  is selected from the group consisting of:
 hydrogen, iso-propyl, phenyl and benzyl.   
     
     
         3 . A process according to  claim 1 , wherein R 2  is selected from the group consisting of:
 phenyl, 3,5-di-methylphenyl and 3,5-di-tert-butyl-phenyl.   
     
     
         4 . A process according to  claim 1 , wherein the compound of formula (III) is selected from the group consisting of:
 (S a ,S)-7-[4,5-Dihydro-4-benzyloxazol-2-yl]-7′-diphenylphosphino-1,1′-spirobiindane;   (S a ,S)-7-[4,5-Dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-methylphenyl)phosphino-1,1′-spirobiindane;   (S a ,S)-7-[4,5-Dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane;   (S a ,S)-7-[4,5-Dihydro-4-phenyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane;   (S a ,S)-7-[4,5-Dihydro-4-isopropyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane; and   (S a )-7-[4,5-Dihydrooxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane.   
     
     
         5 . A process according to  claim 1 , wherein the compound of formula (III) is selected from the group consisting of:
 (S a ,S)-7-[4,5-Dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane;   (S a ,S)-7-[4,5-Dihydro-4-isopropyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane; and   (S a )-7-[4,5-Dihydrooxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane.   
     
     
         6 . A process according to  claim 1 , wherein the catalyst is Ir(L 1 )(L 2 ) n Y
 wherein:   Ir is iridium;   L 1  is a compound of formula (III);   L 2  is selected from the group consisting of: cyclooctene, 1,5-cyclooctadiene, ethylene, 1,5-hexadiene and norbornadiene;   Y is selected from the group consisting of: chloride, iodide, bromide, fluoride, trifluoroacetate, tetrafluoroborate, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, tetraphenylborate, hexafluoroantimonate, hexafluorophosphate, triflate, mesylate, perchlorate, perbromate, periodate, nitrate, hydrogen sulfate and acetylacetonate; and   n is 1 or 2.   
     
     
         7 . A process according to  claim 1 , wherein the catalyst is selected from the group consisting of:
 [Ir((S,S)-7-[4,5-dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][tetrakis[3,5-bis(trifluoromethyl)phenyl]borate];   [Ir((S,S)-7-[4,5-dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][tetrafluoroborate];   [Ir((S,S)-7-[4,5-dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][trifluoromethanesulfonate];   [Ir((S,S)-7-[4,5-dihydro-4-benzyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][chloride];   [Ir((S,S)-7-[4,5-dihydro-4-isopropyloxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][tetrakis[3,5-bis(trifluoromethyl)phenyl]borate]; and   [Ir((S)-7-[4,5-dihydrooxazol-2-yl]-7′-di(3,5-di-tert-butylphenyl)phosphino-1,1′-spirobiindane)(1,5-cyclooctadiene)][tetrakis[3,5-bis(trifluoromethyl) phenyl]borate].   
     
     
         8 . A compound of formula (I) as defined in  claim 1  or a salt thereof obtained by a process according to  claim 1 .