Catalytic asymmetric oxidation of 1H-benzimidazolyl pyridinylmethyl sulfides with cumene hydroperoxide catalyzed by a titanium complex with (S,S)-N,N′-dibenzyl tartramide ligand

A chiral titanium complex, formed in situ from Ti(Oi-Pr)(4), (S,S)-N,N'-dibenzyl tartramide and water was found to serve as an efficient catalyst for the asymmetric oxidations of 1H-benzimidazolyl pyridinylmethyl sulfides with cumene hydroperoxide (CHP) in the absence of a base. Several proton pump inhibitors (PPIs), such as esomeprazole, lansoprazole, rabeprazole and pantoprazole were obtained in high yield (up to 92%) and excellent enantiomeric excess (up to 96%). (C) 2012 Elsevier Ltd. All rights reserved.