Catalytic Dicyanative [4+2] Cycloaddition Triggered by Cyanopalladation of Conjugated Enynes under Aerobic Conditions

摘要

functionality,nits introduction, in particular to carbon-carbon triple bondsnby Ni(0)- or Pd(0) complexes with X-CN (X ) H,1 Si,2 Ge,3 Sn,4nS,5 C,6 B7), has been a major topic in synthetic organic chemistry.nRecently, we developed a catalytic 1,2-dicyanation of alkynes bynPd(II) under aerobic conditions and revealed that this reactionninvolves direct nucleophilic cyanation to C-C triple bonds (antiandnsyn-cyanopalladation).8a,b Since a cyano group on palladium(II)nacts as a pseudo halide and is not likely to be transferred due tonlower nucleophilicity, the above findings are quite interesting. Innthis communication, we focused on the unique reactivity of π-allylnpalladium species generated by the cyanopalladation of conjugatednenynes and investigated its application to the construction of highlynfunctionalized fused cyclohexenes in a stereoselective manner byna new protocol (Scheme 1).