Diethyl [(3-cyano-1-phenylsulfonyl-1H-indol-2-yl)methyl]phosphonate

In the title compound, C20H21N2O5PS, the indole ring is essentially planar, with a maximum deviation of -0.0083 (18) A. The methyl C atom of the methylphosphonate group and the S atom lie 0.104 (2) and -0.2158 (6) A, respectively, from the indole mean plane. The sulfonyl-bound phenyl ring is almost perpendicular to the indole ring system, with a dihedral angle of 82.30 (8)degrees. The ethyl side chains are disordered over two sets of sites, with occupancy factors of 0.737 (5)/0.263 (5) and 0.529 (11)/0.471 (11). In the crystal, molecules are linked into centrosymmetric dimers via C-H...O hydrogen bonds, resulting in an R (2) 2(18) graph-set motif. The crystal structure is further stabilized by C-H...pi interactions.