An efficient, cost-effective and multikilogram-scale process for the synthesis of tenatoprazole 1, an antiulcerative drug, is described. The key steps in this synthesis involve the coupling of 2-mercapto-5-methoxyimidazo [4, 5-b] pyridine 2 with 2-chloromethyl-4-methoxy-3, 5- dimethyl pyridine hydrochloride 3 to yield 4 and its subsequent oxidation with m-CPBA to produce sulfoxide 1. The process has been scaled up for the multikilogram-scale of ...