摘要:
A new and efficient process through a new intermediate, (2E)-2-cyano-3(3,4-dihydroxy-5-nirtrophenyl)prop-2-enoic acid 15, has been described for preparing substantially pure entacapone 1. This new intermediate 15 was prepared by Knoevenagel condensation of 3,4-dihydroxy-5-nitrobenzaldehyde 2 with 2-cyanoacetic acid 14 and was further condensed with diethylamine to get pure entacapone 1. Some of the important process-related impurities of entacapone (17, 18, 19, and 20) were also prepared easily from this intermediate 15.