合成路线1

The reaction of 1-indanone (I) with sodium azide in acetic acid/sulfuric acid gives the tetrahydroquinolone (II), which is reduced with LiAlH4 in THF, yielding the tetrahydroquinoline (III). The reaction of (III) with NaNO2 and sulfuric acid afords the N-nitroso derivative (IV), which is reduced wiith LiAlH4 in THF to the N-amino compound (V). The reaction of (V) with cyclohexane-1,3-dione (VI) gives the monohydrazone (VII), which is cyclized by means of HCl in refluxing acetic acid, yielding the tetracyclic compound (VIII). The reaction of (VIII) with dimethylamine and paraformaldehyde in hot acetic acid provides compound (IX), which is treated with 2-methylimidazole (X) in refluxing water to afford racemic cilansetron (XI). Finally, this racemate is submitted to optical resolution with di-p-toluyl-D-tartaric acid or D-pyroglutamic acid.