Methyl 9-(4-methyl-benzene-sulfon-yl)-4-phenyl-9H-pyrido[3,4-b]indole-3-carboxyl-ate.

The title β-carboline, C26H20N2O4S, which was synthesized via 2 + 2+2-cyclo-addition to an alkynylynamide, is presented. There is one mol-ecule in the asymmetric unit. The tricyclic carbolin framework is essentially planar and subtends an angle of 68.43 (19)° with the attached phenyl ring. In the crystal, the mol-ecules are arranged in a zigzag pattern in the ac plane. Neighbouring mol-ecules are connected via a twofold screw axis or a C 2 axis parallel to the b axis or via a center of inversion.