Chiral enamines derived from 2-(2′-pyrido)acetophenone and 2-(2′-quinolino)acetophenone as ligands in copper(I) catalyzed enantioselective cyclopropanations

Optically active enamines of 2-(2′-pyrido)acetophenone or 2-(2′-quinolino)acetophenone with (R)-1-phenylethylamine, (R)-1-(1-naphthyl)ethylamine, (R)-cyclohexylethylamine, and (R)-phenylglycinol were prepared and their copper(I) complexes used in the enantioselective cyclopropanation of styrene with ethyl- and menthyldiazoacetate. Enantioselectivities of up to 42% enantiomeric excess were obtained for cis/trans 2-phenylcyclopropan-1-carboxylic acid ethyl esters, as determined by gas-liquid chromatography (GLC) on chiral chromatographic columns. © 1995 Wiley-Liss, Inc.