An Allene Approach to Tetrahydrofuran-Fused Bicyclo[2.2.2]oct-2-enes

Construction of Benzopolycycles via Pd-Catalyzed Intermolecular Cyclization of 2,7-Alkadiynylic Carbonates with Terminal Propargyl Tertiary Alcohols

A palladium-catalyzed highly regioselective and chemoselective intermolecular cyclization of 2,7-alkadiynylic carbonates with terminal propargyl tertiary alcohols to construct benzopolycycles containing furan and pyrrole moieties has been developed with a very broad scope. Polycycles containing spirane structures or dispirane structures could be also smoothly synthesized in moderate to good yields. The reaction enjoys excellent regioselectivity.

Benzene construction via Pd-catalyzed cyclization of 2,7-alkadiynylic carbonates in the presence of alkynes

A palladium-catalyzed highly regio- and chemo-selective cyclization of 2,7-alkadiynylic carbonates with functionalized alkynes to construct 1,3-dihydroisobenzofuran and isoindoline derivatives under mild conditions has been developed. Functional groups such as alcohol, sulfonamide, and indoles could be well tolerated. After careful mechanistic studies, a mechanism involving oxidative addition and regioselectivity-defined double alkyne insertions has been proposed.