Synthesis of Alkylidene(<i>gem</i>-Difluorocyclopropanes) from Propargyl Glycolates by a One-Pot Difluorocyclopropenation/Ireland–Claisen Rearrangement Sequence

A one-pot difluorocyclopropenation/Ireland–Claisen rearrangement sequence applied to readily available propargyl glycolates was developed as a route toward functionalized alkylidene­(<i>gem</i>-difluorocyclopropanes). This strategy conveniently avoids the isolation of the unstable 3,3-difluorocyclopropenylcarbinyl glycolates arising from the difluorocyclopropenation. The Ireland–Claisen rearrangement proceeds with high diastereoselectivity and chirality transfer to afford alkylidene­(<i>gem</i>-difluorocyclopropanes) incorporating a quaternary stereocenter and a protected glycolic acid moiety, which are useful building blocks for the preparation of functionalized <i>gem</i>-di­fluoro­cyclo­propanes