MeSiCFBr-Self-Assisted Domino Reaction: Catalytic Synthesis of α,α-Difluorocyclopentanones from Methylvinylketones.

A complete self-assistance strategy based on MeSiCFBr was used in the domino conversion of methylvinylketones into α,α-difluorinated cyclopentanones. Initiated by 5 mol % of nBuNBr, the multistep reaction occurred in one pot under mild conditions via the in situ formation of silyl dienol ethers, difluorocyclopropanation, thermal vinylcyclopropane-cyclopentene rearrangement, and desilylation. The process takes advantage of the multitasking capability of MeSiCFBr as the difluorocarbene source, a silicon-based transfer agent, and a bromine anion releaser.