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 (1R)-camphor based Schiff base ligands, 6-bromo-2hydroxy-1-naphthaldehyde Schiff base of 3-endo-aminoborneol, 48 (SBAB-14), produced (S)-ethyl 2-naphthyl sulfoxide in excellent enantioselectivity (> 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 %).[a] T.Figure 1. Structure of Schiff base ligands that applied in vanadium catalyzed asymmetric sulfoxidation.

Among 20 ligands prepared, endo SBAB‐14 is found to be the most efficient one.