Squaramide/Li+-Catalyzed Direct SN1-Type Reaction of Vinyl Triflates with Difluoroenoxysilanes through Vinyl Cations

Difluoromethylene-skipped enones have been readily obtained from arylvinyltriflates and aryldifluoroenoxysilanes. While these useful compounds are difficult to synthesize by the classical aldol/dehydration approach, the use of a squaramide/Li+ catalyst allows their direct formation via a vinyl carbocation paired with a weakly coordinating perfluorinated alkoxyaluminate. This strategy makes possible a reaction between a typically weak electrophile and a weak nucleophile. Control experiments and DFT computations shed light on the mechanism of this transformation.

Automated summary

Difluoromethylene-skipped enones can be readily synthesized from arylvinyltriflates and aryldifluoroenoxysilanes using a squaramide/Li+ catalyst. This strategy enables the reaction between a typically weak electrophile and a weak nucleophile, which is difficult to achieve with classical aldol/dehydration methods.