Organocatalytic Enantioselective Synthesis of Polycyclic Benzosultams from 2-Amino-β-nitrostyrenes with Cyclic N-Sulfonyl Ketimines

Org Lett. 2024 Feb 23;26(7):1472-1477. doi: 10.1021/acs.orglett.4c00137. Epub 2024 Feb 13.

Abstract

A highly efficient enantioselective [4 + 2] cycloaddition of 2-amino-β-nitrostyrenes with cyclic N-sulfonyl ketimines has been developed. This reaction utilizes an organocatalytic approach, employing a multiple-hydrogen-bonding bifunctional squaramide-based catalyst. The process allows for the precise synthesis of chiral polycyclic benzosultams, showcasing intricate structures that incorporate chiral quaternary centers. Noteworthy outcomes of this method include high yields with excellent enantioselectivities and diastereoselectivities (up to 97% yield, 96% ee, and >20:1 dr).