Patent ID: 9499491
Filing Date: 2016-11-22
CPC Classification: C07C,C07D

Claim Text:
1. A process for preparing bromine free telmisartan in a one pot comprising: (a) chlorination of 2-cyano-4′-methyl biphenyl, a compound of Formula 1 using chlorine gas in a first solvent selected from a chlorinated hydrocarbon to give 4-chloromethyl-2′-cyanobiphenyl, a compound of Formula 2 (b) the compound of Formula 2 is reacted with 2-n-propyl-4-methyl-6-(1′methylbenzimidazol-2′-yl)benzimidazole, a compound of Formula 3 in a second solvent selected from an aromatic hydrocarbon and a ketone at a temperature between 50° C. to 110° C. in the presence of a base and a phase transfer catalyst to yield 2-cyano-4′-(2″-n-propyl-4″-methyl-6″-(1′″-methylbenzimidazol-2″-yl) benzimidazol-1″-ylmethyl) biphenyl, a compound of Formula 4 (c) hydrolysis of the cyano group of the compound of Formula 4 in the presence of a third solvent, which is an alcohol, in the presence of a base at a temperature between 110° C. to 145° C. followed by neutralization with an acid to yield telmisartan, a compound of Formula 5, wherein in step (a) the chlorination of the compound of Formula 1 is carried out using chlorine gas, without a free radical initiator or a catalyst to give the compound of Formula 2.