Stereoselective synthesis of δ-amino-α,β,γ,δ-unsaturated cycloketones via Mannich-type reaction

Abstract A new Mannich-type reaction of aryl propiolaldehydes with benzofuran-3(2H)-one and cyclic secondary amines was established, enabling a completely stereoselective protocol to access a series of unreported δ-amino-α,β,γ,δ-unsaturated cycloketones in generally good yields. This approach could tolerate various cyclic secondary amines including four-, five-, six-membered and bicyclic rings with water as a major by-product.