Reaction of indole (I) with chloroacetyl chloride (II) in the presence of pyridine in toluene afforded the chloro ketone (III). This was then treated with sodium azide in aqueous acetone to furnish the azido ketone (IV). Hydrogenation of (IV) over Pd/C in the presence of a catalytic amount of HOAc gave rise to 3,5-bisindolyl pyrazine (V). Finally, N-methylation of the indole rings with iodomethane and K2CO3 yielded the title compound.

Reaction of indole (I) with chloroacetyl chloride (II) in the presence of pyridine in toluene afforded the chloro ketone (III). This was then treated with sodium azide in aqueous acetone to furnish the azido ketone (IV). Hydrogenation of (IV) over Pd/C in the presence of HCl gave the amino ketone (V). The intermediate 3-indolylglyoxylic chloride (VI) was obtained by acylation of indole (I) with oxalyl chloride in CH2Cl2. Subsequent condensation between acid chloride (VI) and amino ketone (V) produced amide (VII). This was finally cyclized to the desired bisindolyl pyrazinone by treatment with ammonia in a pressure vessel.