Patent ID: 6946579

Claim:
A process for the preparation of a compound of the formula wherein R 1 is hydrogen, (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, or (C 1 -C 6 )alkylthio; R 2 is phenyl, naphthyl or (C 3 -C 12 )cycloallcyl substituted with one or two substituents selected from the group consisting of hydrogen, (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkylthio, (C 2 -C 6 )alkenyl, (C 2 -C 6 )alkynyl, (C 1 -C 6 )alkylhalo, (C 3 -C 8 )cycloalkyl, (C 3 -C 8 )cycloalkenyl or halo; R 3 is selected from the group consisting of hydrogen, (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )alkylthio, (C 2 -C 6 )alkenyl, (C 2 -C 6 )alkynyl, (C 1 -C 6 )alkylhalo, (C 3 -C 8 )cycloalkyl, (C 3 -C 8 )cycloalkenyl or halo, comprising, treating a compound of formula III wherein R 1 , R 2 and R 3 are described as above, with a base and a compound of formula IV: wherein X is a leaving group, to provide the compound of formula V and oxidizing the compound of formula V with an oxidizing agent to provide the compound of formula II.