Patent ID: 7189853

Claim:
A process for the preparation of [R-(E)-1-[[[1-[3-[2-[7-chloro-2-quinolinyl] ethenyl] phenyl]-3-[2-(1-hydroxy-1-methylethyl) phenyl] propyl] thio]methyl] cyclopropaneacetic acid, which comprises: (a) reacting 2-(2-(3(S)-(3-(2-(7-chloro-2-quinolinyl) ethenyl) phenyl)-3-sulfonyl oxy propyl) phenyl)-2-propanol of formula (IV) with an alkali salt of the compound of formula (VI), wherein X═CN or CONH 2 or a mixture thereof in a solvent to get the compound of formula (VII) wherein X═CN or CONH 2 or a mixture thereof; and (b) hydrolyzing the compound of formula (VII) obtained from step (a) to Montelukast in the presence of a base selected from sodium hydroxide, sodium methoxide, sodium secondary butoxide, sodium tertiary butoxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium tertiary butoxide, and potassium carbonate optionally in the solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butyl alcohol, glycol; diethyl ether, diisopropyl ether, methyl isopropyl ether, tetrahydrofuran, diethylene glycol, 1,4-dioxan, methoxy ethanol; and toluene, cyclohexane, hexanes, n-heptane and mixtures of two or more miscible solvents thereof, to get montelukast.