Palladium-Catalyzed Triple Cyclization of 2,7-Alkadiynylic Carbonates with 2-Butyne-1,4-diol or 2-Butyne-1,4-disulfonamides

A palladium-catalyzed highly E-selective triple cyclization of 2,7-alkadiynylic carbonates with 2-butyne-1,4-diol or 2-butyne-1,4-disulfonamides to construct different tricycles such as 6,8-dihydrobenzo[1,2-c:3,4-c ']difuran-1(3H)-one and 1,3,6,7-tetrahydro-8H-furo[3,4-e]isoindol-8-one derivatives has been reported. The alkene group produced and the nucleophilic unit kept in the product provide further opportunity to construct more complicated polycycles. The control experiments showed that the reaction mainly go through an intermolecular insertion of the alkynes before the lactonization or lactamization.