Kinetic Resolution of 2‐Substituted Indolines by <i>N</i>‐Sulfonylation using an Atropisomeric 4‐DMAP‐<i>N</i>‐oxide Organocatalyst

Abstract

The first catalytic kinetic resolution by N-sulfonylation is described. 2-Substituted indolines are resolved (s=2.6-19) using an atropisomeric 4-dimethylaminopyridine-N-oxide (4-DMAP-N-oxide) organocatalyst. Use of 2-isopropyl-4-nitrophenylsulfonyl chloride is critical to the stereodiscrimination and enables facile deprotection of the sulfonamide products with thioglycolic acid. A qualitative model that accounts for the stereodiscrimination is proposed.