Debenzylation of 1-benzyl-4-(1-indolyl)piperidine (I) with H2 and Pd(OH)2 leads to piperidine (II), which is further alkylated by 2-(bromomethyl)pyridine (III) to yield the pyridylmethyl piperidine (IV). Acylation of indole (IV) with oxalyl chloride produces the indoleglyoxylyl chloride (V). This is finally cyclized with the indolyl acetimidate (VI) in the presence of Et3N to produce the target bis-indolyl maleimide.