Patent ID: 7435849
Filing Date: 2008-10-14
Classification: C07C

Abstract:
1. A process for the preparation of a compound of formula I wherein R 1 is hydrogen, C 1 -C 8 alkyl or C 2 -C 8 alkenyl which are unsubstituted or substituted by one or more substituents selected from C 1 -C 8 alkoxy and C 3 -C 8 cycloalkyl; and R 2 and R 3 are combined with the carbon atom to which they are attached to form C 3 -C 7 -cycloalkyl or C 5 -C 8 cycloalkenyl; comprising reacting a compound of formula II wherein R 1 , R 2 and R 3 have the above meanings; with thionyichloride in the presence of tributylamine by continuously adding the thionyl chloride to the reaction mixture.