Preparation of dolasetron useful as anti-emetic agent involves esterification of alcohol with indole-3-carboxylic acid, Dieckmann reaction of ester with strong organic/inorganic base, and dealcoxycarbonylation of the diester

摘要

The present invention relates to a method for obtaining Dolasetron that comprises: a) Esterification of the alcohol of formula (IV) with indole-3-carboxylic acid (compound (III)) or a reactive derivative thereof, to give a compound of formula (V), followed by step b) which includes Dieckmann reaction of the intermediate (V), by reaction with a strong organic or inorganic base, to give the intermediate (VI), and step c) which comprises dealcoxycarbonylation of the intermediate (VI) to give Dolasetron base and, if desired, a pharmaceutically acceptable salt thereof, hydrates or solvates of the base of said salt. The invention also relates to the intermediates (V) and (VI), and methods for obtaining them. With the method of the present invention Dolasetron is obtained at industrial scale with good yields, with decreased use of reactants and solvents, while said method is also of greater atomic efficiency.