Organocatalytic Asymmetric Formal Aza‐[3+3]Cyclo‐additions of 3‐Aminobenzofuran with α,β‐Unsaturated Aldehydes

An organocatalytic asymmetric formal aza‐[3+3]cycloaddition of readily available N‐Tosyl‐3‐aminobenzofuran with α,β‐unsaturated aldehydes was developed for the first time. This method enables the facile synthesis of biologically active and synthetically challenging polysubstituted fused benzofuran derivatives bearing two stereocenters in high yields with excellent diastereo‐, and enantioselectivity (up to >20 : 1 dr, and >99% ee).