合成路线1

In an improved method for the preparation of intermediate (XI), indolodiazepine (I) is condensed with the chiral ferrocenylethyl acetate (II) to produce the N-alkylated compound (III) as an inseparable mixture of diastereoisomers. Subsequent condensation of (III) with aldehyde (IV) and rearrangement in refluxing benzene gives rise to the tetracyclic compound (V) as a single diastereoisomer. Acetolysis of (V) provides amine (VI) along with minor amounts of a partly epimerized compound, which can be removed by chromatography. Then, alkylation of (VI) with benzyl bromide yields the key synthetic intermediate (XI) (6).