Condition-controlled catalytic asymmetric chemodivergent reaction of benzofuran-derived azadienes with 2-indolylmethanols
摘要
A condition-controlled catalytic asymmetric chemodivergent reaction (CACR) of benzofuran-derived azadienes (BDAs) with 2-indolylmethanols has been established. By simply adjusting the reaction temperature, catalytic asymmetric addition reaction or (3+2) annulation between benzofuran-derived azadienes and 2-indolylmethanols was achieved, leading to the synthesis of two distinct classes of chiral furan derivatives in high yields with excellent enantioselectivities. By switching the catalytic system to a cooperative catalysis of Brønsted acid and Lewis acid, a rearrangement (4+3) annulation was realized, providing access to a unique family of furan-fused seven-membered rings in good yields. This work represents the first chemodivergent reaction of benzofuran-derived azadienes utilizing their triple reactivity, the first condition-controlled catalytic asymmetric chemodivergent reaction of 2-indolylmethanols, and the first rearrangement (4+3) annulation of benzofuran-derived azadienes. This study has not only settled the challenging issues in catalytic asymmetric chemodivergent reactions, but also greatly enriched the chemistry of benzofuran-derived azadienes and indolylmethanols.