Catalytic process for the preparation of thiazole derivatives

摘要

A process for the preparation of a compound of formula (I) wherein Q is CH or N; Y is NO₂ or CN; Z is CHR₃, O, NR₃ or S; R₁ and R₂ are C₁-C₈ alkyl or together form an alkylene bridge having two or three carbon atoms; by reacting a compound of formula H₂C=C(X)CH₂NCS wherein X is a leaving group, with a chlorinating agent in the presence of a catalytic amount of SO₂. to form a compound of formula (III) and the compound of formula (III) is reacted with a compound of formula R₁NHC(=QY)ZR₂ wherein R₁, R₂, Y, Z and Q are as defined for compound (I).