Convenient preparations and Michael reactions of 4-fluoroalkylated but-2-en-4-olides

Abstract

Trifluoromethyl, heptafluoropropyl and chlorodifluoromethyl substituted but-2-en-4-olides have been prepared both from 2-trimethylsiloxyfuran by fluoroalkylation with the corresponding bis(fluoroalkanoyl) peroxide and from 2-fluoroalkylfuran by oxidation with m-nitrobenzenesulfonyl peroxide. 4-Difluoromethylbut-2-en-4-olide was also prepared by chlorodifluoromethylation of 2-methoxyfuran followed by reduction of the chlorine. The 4-trifluoromethylated butenolide, thus prepared, could be readily converted into the anion by treatment with weak base. The anion so formed then reacted with electron-deficient olefins to give 4,4-disubstituted butenolides.