Patent ID: 7795471

Claim:
A process for the preparation of a compound of the formula: wherein R 1 is lower alkyl, R 4 is hydrogen or lower alkyl, and Z is optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted amino, optionally substituted lower alkoxy, optionally substituted carbocyclyl or optionally substituted heterocyclyl, comprising: a) reacting a compound of the formula (IV) wherein R 2 is lower alkyl with a compound of the formula (VI) R 3 —CHO (VI) wherein R 3 is optionally substituted phenyl to obtain a compound (VII), wherein R 2 and R 3 are defined as above, b) reacting (VII) with a base in an organic solvent to obtain the compound (VIII) c) hydrolyzing the compound (VIII) to obtain compound (IX) d) reacting compound (IX): wherein R2 is lower alkyl with a compound of the formula: wherein R1 is lower alkyl to obtain a compound of the formula: wherein R1 and R2 are each independently lower alkyl, e) oxidizing compound (X) to obtain compound (I) wherein R1 and R2 are each independently lower alkyl, f) hydrolyzing Compound (I) to obtain Compound (I′) g) reacting Compound (I′) with a compound of the formula: R 4 NH—Z (XI) wherein R 4 and Z are the same as defined above, to obtain compound (XII).