Patent ID: 7034167

Claim:
A process for preparing a compound of structural formula I: wherein R 1 is C 2-4 alkenyl, C 2-4 alkynyl, or C 1-6 alkyl unsubstituted or substituted with one to three substituents independently selected from fluorine, hydroxy, amino, mercapto, C 1-3 alkoxy, and C 1-3 alkylthio; and R 2 is C 1-6 alkyl or aryl unsubstituted or substituted with one to three substituents independently selected from methoxy, methyl, and fluorine; comprising the step of cleaving the R 3 protecting group in a compound of structural formula V: wherein R 3 represents benzyl unsubstituted or substituted with one to three substituents independently selected from methyl, methoxy, halogen, and nitro; by catalytic hydrogenolysis.