Patent ID: 8609859

Claim:
A one pot process for the synthesis of irbesartan comprising the steps of: a. Reacting 2-n-butyl-1,3-diazaspiro[4,4]-non-1-ene-4-one hydrochloride of Formula III with a halomethyl biphenyl compound of formula IV in water, in the absence of organic solvent, in the presence of a base with the optional use of a phase transfer catalyst at 45-65° C. to yield 2-n-butyl-3[(2′-cyanobiphenyl)-4-yl]methyl-1,3-diazaspiro[4,4]-non-1-ene-4-one of formula II b. Extracting the product of step (a) in a non polar solvent, followed by addition of sodium azide and triethyl amine hydrochloride at 95-105° C. and stirring the reaction mass for 33-36 hours to form irbesartan; c. Adjusting the pH of the reaction mass of step (b) to 10-11 with a caustic solution upon completion of the reaction, followed by separation of aqueous and organic layers; d. Adjusting the pH of the aqueous layer from step (c) to 4-4.5 with concentrated hydrochloric acid to precipitate product; e. Treating the wet product of step (d) with polar solvent at reflux temperature; f. Isolating the crude irbesartan; g. Purifying the crude irbesartan in a water-miscible solvent containing about 5% v/v water to yield irbesartan.