“…Ammonium ylides are generated by deprotonation of quaternary ammonium salts previously synthesized − or formed in situ as quaternary derivatives of DABCO − or cinchona alkaloids. − They undergo inter- − ,, or intramolecular , Michael additions. Among Michael acceptors, there are α,β-unsaturated aldehydes, ,,, ketones, ,− ,− esters, ,− ,,, α-nitroesters, amides, ,, sulfones, ,,, lactones and lactams, acrylonitrile, − , and para -quinone methides . Usually, as a result, racemic − , or optically active ,− cyclopropanes are formed by MIRC ,, (Scheme , path A).…”