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.
