Structures of Three New (Phenylsulfonyl)Indole Derivatives

Abstract  

Three new 1-(phenylsulfonyl)indole derivatives, 3-acetyl-2-ethyl-1-(phenylsulfonyl)indole, (I), 2-benzyl-1-(phenylsulfonyl)indole, (II), and 3-trimethylsilylethynyl-1-(phenylsulfonyl)indole, (III), have been synthesized and their crystal structures determined by single crystal X-ray crystallography. (I), C₁₈H₁₇NO₃S, is triclinic with space group P-1 and cell constants: a = 8.6129(2) Å, b = 8.8366(2) Å, c = 11.0108(2) Å, α = 72.7920(1)°, β = 75.0120(1)°, γ = 77.2550(1)°, V = 763.79(3) ų and Z = 2. (II), C₂₁H₁₇NO₂S, is monoclinic with space group P21/n and cell constants: a = 10.8355(18) Å, b = 10.6987(19) Å, c = 14.472(3) Å, β = 75.0120(1), V = 1675.2(5) ų and Z = 4. (III), C₁₉H₁₉NO₂SSi, is monoclinic with, space group P21/c and cell constants: a = 12.9596(1) Å, b = 10.543(3) Å, c = 13.543(2) Å, β = 93.58°, V = 1846.8(6)ų and Z = 4. All three have the same (phenylsulfonyl)indole skeleton with different ligands attached to the 2- and 3-sites of the indole ring. The angle between the mean planes of the indole and benzyl groups is 76.9(6)° (I), 82.9(3)° (II), 89.6(2)° (III) and between the sulfonyl group with the indole and benzyl rings is 61.2(9)° (I), 59.0((5)° (II), 51.5(6)°, 42.5(8)° (III) and 51.5(6)°(I), 44.3(8)° (II), 47.2(8)° (III), respectively. In addition to the ligand substitutions, weak intermolecular C–H···O hydrogen bond interactions and π stacking interactions between the π orbitals of nearby indole and phenyl rings influence these twist angles. Comparison to a MOPAC AM1 computational calculation supports these observations.