Enantioselective Synthesis of 1,2‐Benzothiazine 1‐Imines via Ru^II/Chiral Carboxylic Acid‐Catalyzed C−H Alkylation/Cyclization

Abstract

Sulfondiimines are diaza-analogues of sulfones with a chiral sulfur center. Compared to sulfones and sulfoximines, their synthesis and transformations have so far been studied to a lesser extent. Here, we report the enantioselective synthesis of 1,2-benzothiazine 1-imines, i.e., cyclic sulfondiimine derivatives from sulfondiimines and sulfoxonium ylides via C-H alkylation/cyclization reactions. The combination of [Ru(p-cymene)Cl₂ ]₂ and a newly developed chiral spiro carboxylic acid is key to achieving high enantioselectivity.