PROCESS FOR PREPARING ONDASETRON AND CARBAZOLONE DERIVATIVES AS USEFUL INTERMEDIATES IN THE SYNTHESIS OF ONDANSETRON

摘要

The invention relates to carbazolone derivatives of the formula wherein A stands for a group of the formula (V), wherein R means a hydroxyl or 2-methyl-1H-imidazol-1-yl group; B represents a group of formula (VI) wherein R1 means hydrogen or a methyl or ethyl group; or A and B together form a group of the formula (VII) wherein R2 means a methyl or ethyl group; or A and B together form a group of formula (VIII) which are intermediates for the preparation of ondasetron of the formula (II) in a process specified by the invention.