Synthesis of a highly hindered hydrindanone via alpha-carbonyl radical cyclization: enantiospecific formal syntheses of (-)-pinguisenol and (-)-alpha-pinguisene.

An enantiospecific synthesis of Schinzer's ketone 3 from (R)-(+)-pulegone via alpha-carbonyl radical cyclization was accomplished. This work also constitutes an enantiospecific formal syntheses of (-)-pinguisenol and (-)-alpha-pinguisene. The intermediate ketone 4 would be useful for the synthesis of other pinguisane-type sesquiterpenes.