4-(1,3-Benzothia-zol-2-yl)-5-methyl-2-phenyl-1-propynyl-1H-pyrazol-3(2H)-one.

The title compound, C(20)H(15)N(3)OS, is a 1H-pyrazol-3(2H)-one having aromatic 4-(1,3-benzothia-zol-2-yl) and 2-phenyl substit-uents. The five-membered ring and the fused-ring system are close to planar, the r.m.s. deviations being 0.025 and 0.005 Å, respectively. The five-membered ring is aligned at 67.5 (1)° with respect to the phenyl ring and at 4.7 (1)° with respect to the fused-ring system. In the crystal, adjacent mol-ecules are linked through the acetyl-enic H atom by a C-H⋯O hydrogen bond into C(8) chains propagating in [010].