Synthesis and Crystal Structure Determination of 3-Phenyl-2-(2-phenylhydrazino)-4<Emphasis Type="Italic">H</Emphasis>-1-benzothiopyran-4-one

Abstract  

A new type of substituted benzothiopyranone, 3-phenyl-2-(2-phenylhydrazino)-4H-1-benzothiopyran-4-one, has been prepared by the condensation-acid cyclization of polylithiated phenylacetic acid phenylhydrazide with lithiated methyl thiosalicylate. Absorption spectra, especially ¹³C NMR, provided good indication of its structure, which was conclusively established with X-ray crystal structure analysis. In comparison to the few benzothiopyran X-ray reports documented, the benzothiopyranone ring of the molecule was found to be essentially planar, with the 3-phenyl ring nearly perpendicular to the benzothiopyranone fused-ring system. Crystals of C₂₁H₁₆N₂OS are orthorhombic, P2₁2₁2₁, a = 10.140(4) ?, b = 10.432(4) ?, c = 16.228(7) ?, Z = 4, V = 1717(1) ?³, R ₁ = 0.0267 and wR ₂ = 0.0725 for reflections with I > 2σ(I). The molecular packing in the crystal is the result of N–H···O hydrogen bonding.