Highly stereoselective construction of tetrahydroquinolines via cascade aza-Michael-Michael reaction: Formal [4+2] cycloaddition of beta,gamma-unsaturated alpha-ketoesters with 2-aminochalcones

摘要

An efficient cascade aza-Michael-Michael sequence for the preparation of tetrahydroquinolines has been established. Three contiguous stereogenic centers are created with high levels of enantioselectivities (79-99% ee) and exclusive diastereoselectivities in the presence of a bifunctional squaramide. This approach is compatible with a broad range of beta,gamma-unsaturated alpha-ketoesters and 2-aminochalcones. Our protocol indicated that beta-site of beta,gamma-unsaturated alpha-ketoester is an available pro-nucleophilic site. (C) 2018 Elsevier Ltd. All rights reserved.