Asymmetric Synthesis of Bicyclo[4.3.1]decadienes and Bicyclo[3.3.2]decadienes via [6 + 3] Trimethylenemethane Cycloaddition with Tropones

The cyanosubstituted trimethylenemethane donor undergoes palladium-catalyzed [6 + 3] cycloaddition with a variety of tropones to yield bicyclo[4.3.1]decadienes in excellent regio-, diastereo-, and enantioselectivity. Products of the Pd-TMM [6 + 3] cycloaddition participate in a thermal [3,3] sigmatropic rearrangement to yield bicyclo[3.3.2]decadienes in good yield.