Acylsilane and trifluoromethyltrimethylsilane gave, under fluoride initiation, a difluoroenoxysilane which is used in situ in a Lewis acid catalyzed coupling with a prenyl ester or a benzylic bromide. The advantage of this one-pot procedure was illustrated by its use in the synthesis of gem-difluoro analogues of terpenes (dehydro-ar-curcumene and ar-turmerone).