Carbocupration of acetylenic acetals and ketals** synthesis of α-β ethylenic acetals, and of dienals and dienones

Abstract

The regio selectivity of the carbocupration reaction of substituted and non substituted α-acetylenic ketals and acetals is discussed. Lithium di organocuprates add regio and stereoselectively. The functionalized vinyl cuprates thus obtained, can be trapped by a large variety of electrophi1 es : alkyl, alkenyl, alkynyl and aryl halides, α-β unsaturated esters or ketones. The reaction is illustrated by the synthesis of manicone, of pure E geranial, and of 2,4-(E,Z) dienals. © 1983 IUPAC