Catalytic palladium-oxyallyl cycloaddition.

摘要: Exploration of intermediates that enable chemoselective cycloaddition reactions and expeditious construction fused- or bridged-ring systems is a continuous challenge for organic synthesis. As an intermediate interest, the oxyallyl cation has been harnessed to synthesize architectures containing seven-membered rings via (4+3) cycloaddition. However, its potential access five-membered skeletons underdeveloped, largely due thermally forbidden (3+2) pathway. Here, combination tailored precursor Pd(0) catalyst generates Pd-oxyallyl cyclizes with conjugated dienes produce diverse array tetrahydrofuran skeletons. The overrides conventional selectivity by proceeding through stepwise pathway involving Pd-allyl transfer ring closure sequence. Subsequent treatment adducts palladium converts heterocycles carbocyclic cyclopentanones.