Enantioselective Construction of Aryl‐Substituted All‐Carbon Quaternary Stereocenters by Using Tertiary Amine–Thiourea‐Catalyzed Michael Additions

Abstract

AbstractA catalytic enantioselective synthetic strategy for the aryl‐substituted all‐carbon quaternary stereocenters of bioactive hydrodibenzofuran alkaloids was achieved by the Michael addition reaction of α‐cyano ketones and acrylates using a chiral tertiary amine–thiourea catalyst. This method can tolerate steric bulkiness and multiple functional groups, and 32 Michael adducts were prepared in good to excellent yields with moderate to good enantioselectivities. The enantiopurity of the products could also be enriched up to 99 % ee after one recrystallization. This enantioselective Michael addition features a low cost, metal‐free, and easily operable procedure that can provide multifunctionalized enantiopure Michael adducts on a four‐gram scale and supply sufficient amounts of potential precursors for a number of hydrodibenzofuran natural products.