Patent ID: 8183370

Claim:
A process for the preparation of abacavir of formula (I), or a pharmaceutically acceptable salt thereof, comprising (a) reacting a compound of formula (II) with an inorganic base in a mixture of a (C 1 -C 6 )-alcohol and water, wherein R is H or a (C 1 -C 4 )-alkyl radical; and (b) isolating the abacavir of either as free base by crystallization or as a pharmaceutically acceptable salt by the alternative sequences, where for a salt: (b1) when at the end of reaction (a) the mixture is a solution, then, comprising: (i) adding a solvent selected from the group consisting of ethyl ether, isopropyl ether, tert-butylmethyl ether, di-n-butyl ether, (C6-C8)-aromatic hydrocarbons and chlorine-containing solvents; (ii) separating the aqueous phase; and (iii) precipitating the pharmaceutically acceptable salt from the organic phase by addition of the appropriate amount of the corresponding pharmaceutically acceptable acid; or (b2) when at the end of the reaction a separation of the mixture is observed in two phases as a two-phase system, then, comprising: (i) optionally adding to the two-phase system a solvent selected from the group consisting of ethyl ether, isopropyl ether, tert-butylmethyl ether, di-n-butyl ether, (C6-C8)-aromatic hydrocarbons and chlorine-containing solvents; (ii) separating the aqueous phase and (iii) precipitating the pharmaceutically acceptable salt of abacavir from the organic phase by addition of the appropriate amount of the corresponding pharmaceutically acceptable acid; or, where for a free base: alternatively isolating the abacavir as free base and converting the free base into a pharmaceutically acceptable salt by treating the free base with a suitable amount of the corresponding pharmaceutically acceptable acid.