Experimental

R factor = 0.039; wR factor = 0.101; data-to-parameter ratio = 19.6. In the title compound, C15H12ClNO2S, the indole ring is essentially planar (r.m.s. deviation = 0.0107 Å) and makes a dihedral angle of 85.01 (6) with the benzene ring. In the crystal, three C—H O hydrogen bonds result in a hydrogen-bonded spiral running parallel to the c axis. Related literature For background to the use of indoles as scaffolds in the synthesis of HIV-agents, see: Hassam et al. (2012). For the crystal structure of a closely related compound, see: Beddoes et al. (1986)