Camphor‐Based Schiff Base Of 3‐ <i>Endo</i> ‐Aminoborneol (SBAB): Novel Ligand for Vanadium‐Catalyzed Asymmetric Sulfoxidation and Subsequent Kinetic Resolution

Abstract

Abstract Novel in situ formed vanadium Schiff base complexes, namely vanadyl Schiff base of 3‐ exo ‐aminoisoborneol (V(O)‐SBAIB) and vanadyl Schiff base of 3‐ endo ‐aminoborneol (V(O)‐SBAB), were demonstrated to catalyze an enantioselective sulfoxidation reaction. Among the twenty substitutionally and electronically different (1 R )‐camphor based Schiff base ligands, 6‐bromo‐2‐hydroxy‐1‐naphthaldehyde Schiff base of 3‐ endo ‐aminoborneol, 48 (SBAB‐14), produced ( S )‐ethyl 2‐naphthyl sulfoxide in excellent enantioselectivity (&gt;99 %) with good yield (72 %). In an optimized reaction condition, 1.5 mol% 48 (SBAB‐14) catalyzed asymmetric sulfoxidation with concomitant kinetic resolution of various alkyl aryl sulfides and rendered corresponding sulfoxides with high ee (up to 97 %) with moderate yield (up to 74 %).