Patent ID: 8889873

Claim:
A process for the preparation of a proton pump inhibitor of formula 1 from the corresponding sulfide compound of the formula 4: wherein: S* represents a chiral sulfur atom; ring A represents benzene or pyridine ring optionally having a substituent independently selected from the group consisting of halide, cyano, nitro, alkyl selected from C 1 -C 6 optionally substituted, aryl, hydroxy, OR 5 , C(O)R 5 , and COOR 5 , wherein R 5 is selected from C 1 -C 6 alkyl; X represents a nitrogen atom; R 1 represents a hydrogen atom; R 2 , R 3 , and R 4 can each be a hydrogen atom, or are independently selected from the group consisting of C 1 -C 6 alkyl, OR 10 , and COOR 10 , wherein R 10 is selected from C 1 -C 6 alkyl; comprising: oxidizing the compound of formula 4 in a solvent with an oxygen atom donor in a presence of a metal complex, wherein said metal complex is prepared from an optically active ligand, which is selected from the group consisting of: salen-type complexing ligands, salan-type complexing ligands, and complexing ligands having bidentate, tridentate or tetradentate azomethine or hydrogenated azomethine groups; and a metal precursor comprising a metal selected from the group consisting of Mn, Cu, and Fe.