Phosphine-Catalyzed Sequential [4 + 3] Domino Annulation/Allylic Alkylation Reaction of MBH Carbonates: Efficient Construction of Seven-Membered Heterocycles

Phosphine-catalyzed intermolecular sequential [4 + 3] domino annulation/allylic alkylation of MBH carbonates and N-tosyl azadienes is reported. A series of functionalized benzofuran-fused seven-membered nitrogen-heterocyclic compounds with one quaternary center were obtained in good to excellent yields. In this sequential reaction, three new bonds were formed in one pot, and the MBH carbonates serve as 1,2,3-C3 synthon and C1 synthon at the same time.本文报道了膦催化的MBH碳酸酯（Morita-Baylis-Hillman carbonate）与N-对甲苯磺酰基氮杂二烯的分子间串联[4+3]多米诺环化/烯丙基烷基化反应。该反应可得到一系列带有一个季碳中心的官能化苯并呋喃稠合七元氮杂环化合物，产物收率为中等到优异。在该串联过程中，一锅法即可构建三个全新化学键，且MBH碳酸酯同时作为1,2,3-三碳合成子与一碳合成子参与反应。