Synthesis of steroidal allenyl ketones
Abstract
Alkylation of the allenic acid fluoride (1) is a regiospecific reaction which depends on the nature of the alkylating agent; whereas treatment of (1) with lithium dimethylcopper affords the 20-vinylic methylated 22-keto-steroid (3), reaction with dimethylcadmiu provides a mixture of isomeric allenyl methyl ketones (5a) and (5b).