Asymmetric total synthesis of (+)-aphanamol I based on the transition metal catalyzed [5+2] cycloaddition of allenes and vinylcyclopropanes

[GRAPHICS] A concise asymmetric total synthesis of (+)-aphanamol I is described, based on the transition metal catalyzed [5 + 2] allenyl-vinylcyclopropane cycloa ddition. The key cycloaddition precursor is convergently assembled from (R) -(+)-limonene and cyclopropane diester through a novel decarboxylative dehy dration reaction. The metal-catalyzed [5 + 2] cycloaddition of this precurs or proceeds with complete chemo, endo/exo, and diastereoselectivity in 93% yield, representing an effective general route to bicyclo[5.3.0]decane deri vatives.