5,7-Diacetyl-13-benzyl-7,8-dihydro-5H,8aH,13H-di-indolo[2,3-c;2,3-d] pyrimidin-8-yl acetate, the result of an intra-molecular cyclo-addition between an N-benzyl-indole and a 1,2,4,5-tetra-zine

An intra-molecular Diels-Alder-type cyclo-addition between an indole and a 1,2,4,5-tetra-zine produced the title compound, C29H26N4O4, the first example of a penta-heterocyclic structure obtained via loss of nitro-gen and addition of the elements of acetic anhydride. Of the four N atoms in the mol-ecule, one is in a dihydro-indole, while the other three are in an N,N′-diacyl- amidrazone unit, of which there are no previous examples. The N,N′-diacyl-amidrazone is almost planar and is involved in π-π stacking with the N-benzyl phenyl ring. There are inter-molecular C - H⋯O hydrogen bonds, linking the mol-ecules into chains. © International Union of Crystallography 2007.