Regio- and stereoselective synthesis of gem-difluorocyclopropanes using 4-bromo-4,4-difluorocrotonate

Article abstract of DOI:10.1016/S0040-4039(00)75998-3

Regio- and stereoselective formation of the functionalized gem-difluorocyclopropane derivative was achieved through the Michael addition of lithium enolate of ester or amide with 4-bromo-4,4-difluorocrotonate 1 followed by the triethylborane-O₂