Enantioselective Synthesis of 1,2‐Benzothiazine 1‐Imines via Ru<sup>II</sup>/Chiral Carboxylic Acid‐Catalyzed C−H Alkylation/Cyclization
Long‐Tao Huang, Yuta Kitakawa, Kodai Yamada, Futa Kamiyama, M. Kojima, Tatsuhiko Yoshino, Shigeki Matsunaga
Abstract
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)Cl 2 ] 2 and a newly developed chiral spiro carboxylic acid is key to achieving high enantioselectivity.
Topics & Concepts
Enantioselective synthesisAlkylationCatalysisChemistryBenzothiazineCarboxylic acidMedicinal chemistryOrganic chemistryCatalytic C–H Functionalization MethodsSynthesis and Catalytic ReactionsPhenothiazines and Benzothiazines Synthesis and Activities