Process for the preparation of 2-(4,4-difluoro-but-3-enylthio)-benz-thiazoles and -benzoxades

A process for preparing a compound of formula (I) by (a) reacting a substituted ortho-nitro or -nitroso phenol or a substituted ortho-nitro or -nitroso thiophenol with an alkali metal dithionite reducing agent in an alkaline reaction medium in the presence of carbon disulphide, to form a substituted 2-mercaptobenz-oxazole or -thiazole, acidifying the reaction mixture and collecting the 2-mercaptobenz-oxazole or -thiazole; and then (b) reacting the 2-mercaptobenz-oxazole or -thiazole with a compound of formula (IV) CF2=CH-CH2-CH2-L(IV) wherein L is a good leaving group.