Organocatalytic Asymmetric Mannich‐Type Reaction of Isocyanoacetates with N‐(2‐Benzothiazolyl)imines

An organocatalytic asymmetric synthesis of directly linked benzothiazole-dihydroimidazoles with two adjacent tertiary-quaternary stereocenters through a Mannich-type reaction of isocyanoacetates with N-(2-benzothiazolyl)imines is disclosed. When employing bifunctional dihydroquinine-derived squaramide as catalyst, moderate to excellent yields (up to 97% yield), moderate diastereoselectivities and excellent enantioselectivities (up to > 99% ee) were obtained for a variety of substrates. In addition, the transformation of the resulted directly linked benzothiazole-dihydroimidazole into highly functionalized α,β-diamino esters was also demonstrated.