New Tandem Ring Enlargements of Bicyclo[3.3.0]octanes to Bicyclo[5.5.0]dodecanes and Subsequent Conversions into Tricyclo[5.5.0.0.2,9]dodecane and Tricyclo[5.5.0.02,10]dodecane Derivatives

Abstract

Potential precursors of tetracyclo[5.5.0.0 4,10 ]dodecatetraenes B were synthesized by means of ring enlargements of bicyclo[3.3.0]octanes to bicyclo[5.5.0]dodecanes through enol ether/ketene additions and Michael-induced reactions. Basecatalyzed or oxidative ring closures of the highly func-