| abstract |
The invention relates to carbazolone derivatives of the formula wherein A represents a group of formula wherein R represents a hydroxyl or 2-methyl-1H-imidazol-1-yl group; B represents a group of formula wherein R1 represents hydrogen or a methyl or ethyl group; or A and B together form a group of formula wherein R2 means a methyl or ethyl group; or A and B together form a group of formula The above compounds are useful intermediates in the: syn-thesis of ondansetron of formula chemically 9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]--1,2,3,9-tetrahydro-4H-carbazol-4-one. The invention further relates to a novel process for the preparation of compounds of the formula (I), wherein A and B are the same as in formula (I) but B may be also hydrogen. Thus, this novel process is suitable for the preparation of ondansetron itself. |