A new titanate/(+)-(1R,2S)-cis-1-amino-2-indanol system for the asymmetric synthesis of (S)-tenatoprazole

Asymmetric oxidation of TU-501 has been achieved using cumene hydroperoxide (CHP) in the presence of titanium tetraisopropoxide (Ti(OiPr)4) and (+)-(1R,2S)-cis-1-amino-2-indanol, in a polar aprotic solvent at 0–20°C, to chemoselectively give (S)-TU-199 with an enantiomeric excess of >99%, a chemoselectivity of >90% and a chemical yield of >90%.