Patent ID: 7041832

Claim:
A process for preparing losartan of formula (I) and pharmaceutically acceptable salts thereof comprising: a) contacting a compound of formula (II): wherein each R 1 , R 2 , R 1 ′, R 2 ′, R 1 ″ and R 2 ″ is independently selected from the group consisting of hydrogen; halogen; alkyl, which may be optionally substituted with one or more halogen, hydroxy or lower alkoxy; alkenyl, which may be optionally substituted with one or more halogen, hydroxy or lower alkoxy; nitro; cyano; vinyl; styryl; a group of formula —COR 3 , —CO 2 R 3 , —OR 3 , —SR 3 , —SO 2 R 3 , —NR 3 R 4 , —NCO 2 R 3 , or —OCO 2 R 3 where R 3 and R 4 are atoms and radicals independently selected from the group consisting of hydrogen, lower alkyl, aralkyl, aryl and; or where R 1 and R 2 or R 1 ′ and R 2 ′ or R 1 ″ and R 2 ″ occupy two adjacent positions they may be joined to form an optionally substituted carbocyclic ring, and an acid in a diluent comprising a liquid ketone for a period of time sufficient to substantially convert the compound to losartan, b) basifying the diluent, c) evaporating liquid ketone, leaving a residue, d) precipitating a triarylmethyl alcohol of formula (III): wherein R 1 , R 2 , R 1 ′, R 2 ′, R 1 ″ and R 2 ″ are as previously defined, from the residue, e) separating the precipitated triarylmethyl alcohol from the residue, f) acidifying the residue, g) precipitating losartan from the residue, and h) separating losartan from the residue.