Patent ID: 6303787
Filing Date: 2001-10-16
Classification: C07D

Abstract:
A process for the preparation of 5-methoxy-2-(((3,5-dimethyl-4-methoxy-2-pyridinyl)methyl)sulphinyl)-1H -benzimidazole (Omeprazole) of formula I, which comprises: ##STR34##i) Rearranging 4-nitro-2,3,5-trimethyl pyridine-N-oxide of the formula-IV to 2-acetyloxymethyl-3,5-dimethyl-4-nitropyridine of Formula XI by employing acetic anhydride;ii) Hydrolyzing the compound of formula-XI to 2-hydroxymethyl-3,5-dimethyl-4-nitropyridine of formula-II by employing a base;iii) Substituting the hydroxy group of the compound of formula-II with a chloride ion through the use of a chlorinating agent at a temperature in the range of 0-15.degree. C. and neutralization with a base to obtain 2-chloromethyl-3,5-dimethyl-4-nitropyridine of formula III;iv) Coupling the compound of formula-III with 5-methoxy-2-mercapto benzimidazole, of formula VII in aqueous alkali to obtain 5-methoxy-2(((3,5-dimethyl-4-nitro-2-pyridinyl)methyl)thio)-1H-benzimidazo le of formula-VIII;v) Converting the compound of formula-VIII by reflux with sodium methoxide solution to obtain 5-methoxy-2-(((3,5-dimethyl-4-methoxy-2-pyridinyl)methyl)thio)-1H-benzimid azole of formula-IX andvi) Oxidizing the compound of formula-IX with an oxidizing agent at a temperature in the range of 5-10.degree. C. to obtain 5-methoxy-2-(((3,5-dimethyl-4-methoxy-2-pyridinyl)methyl)sulphinyl)1H-benz imidazole (Omeprazole) of formula I.