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Rhodium-catalyzed [2+2+2] cycloaddition of carbon disulfide to o,N-dialkynyltosylanilines gives two isomeric indolothiopyranthiones, a violet and a red isomer. This is the first crystal structure of a red isomer, which crystallizes with one solvent molecule of dichloromethane in the asymmetric unit, C24H17NO2S3·CH2Cl2. In the extended structure, centrosymmetric pairs of the planar annulated system are arranged in strands and solvent molecules fill the space between the strands.

The title compound, C19H15NO2S3, is the first example of a dithia analogue of pyrano[3,4-b]indolone. The almost planar thiopyranoindolethione ring system (r.m.s. deviation for all non-H atoms = 0.030 Å) makes a dihedral angle of 80.70 (8)° with the p-tolyl ring. In the crystal, molecules are connected via C—H...O hydrogen bonds into two chains along the b axis. These chains are connected via π–π interactions between symmetry-related thiopyranoindolethione ring systems [centroid–centroid distance = 3.588 (1) Å].