Synthesis of trifluoro- or difluoromethylated olefins by regio- and stereocontrolled S(N)2' reactions of gem-difluorinated vinyloxiranes.

Hisanori Ueki, Takashi Chiba, Tomoya Kitazume

Index: J. Org. Chem. 71 , 3506-3511, (2006)

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Abstract

This paper presents a highly stereoselective synthesis of trifluoro- or difluoromethylated olefins via an S(N)2' type fluorination or reductions of gem-difluorinated vinyloxiranes. Their fluorination with HF-Py furnished trifluoromethylated allylic alcohols with exclusive E selectivity. On the other hand, their reduction with DIBAL-H afforded difluoromethylated E-allylic alcohols predominantly, whereas the corresponding Z isomers were formed exclusively by treatment with BH3.THF.