Organocatalytic Asymmetric Transformations Involving the Cyclic Imine Moiety in Indole and Isoindole Related Heterocycles

Indole and isoindole skeletons are pervasive structural moieties in a plethora of biologically active and synthetically useful compounds as well as natural products. In view of the significance of this framework, the development of efficient protocols to access the purely chiral nitrogen-containing heterocycles has drawn much attention. Among them, the asymmetric transformations based on cyclic imines via organocatalysis strategies have provided an exciting platform from which various nitrogen heterocycles with distinct structural characters were quickly and conveniently prepared with high chemo-, diastereo- and enantioselectivities. This review, organized on the basis of two primary starting materials, summarizes the progress made in the field of organocatalytic asymmetric reactions involving five-membered cyclic imines and their precursors as masked cyclic imines which usually feature or generate in situ a carbon-nitrogen double bond embedded in 3H-indole, 1H-isoindole and 1,2-benzisothiazole 1,1-dioxide ring systems published since the beginning of 2008, including the substrate scope, mechanisms, applications and limitations.