2-(Naphthalen-1-yl)-4-(naphthalen-1-yl-methyl-idene)-1,3-oxazol-5(4H)-one

Dihydrooxazolones and dihydroimidazolones derived from acylglycines: syntheses, molecular structures and supramolecular assembly

Syntheses and structures are described for some alkylidene-substituted dihydrooxazolones and dihydroimidazoles derived from simple acylglycines. A second, triclinic, polymorph of 4-benzylidene-2-(4-methylphenyl)-1,3-oxazol-5(4H)-one, C17H13NO2, (I), has been identified and the structure of 2-methyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one, C9H7NO2S, (II), has been rerefined taking into account the orientational disorder of the thienyl group in each of the two independent molecules. The reactions of phenylhydrazine with 2-phenyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one or 2-(4-methylphenyl)-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one yield, respectively, 3-anilino-2-phenyl-5-[(thiophen-2-yl)methylidene]-3,5-dihydro-4H-imidazol-4-one, C10H15N3OS, (III), and 3-anilino-2-(4-methylphenyl)-5-[(thiophen-2-yl)methylidene]-3,5-dihydro-4H-imidazol-4-one, C21H17N3OS, (IV), which both exhibit orientational disorder in their thienyl groups. The reactions of 2-phenyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one with hydrazine hydrate or with water yield, respectively, N-[3-hydrazinyl-3-oxo-1-(thiophen-2-yl)prop-1-en-2-yl]benzamide and 2-(benzoylamino)-3-(thiophen-2-yl)prop-2-enoic acid, which in turn react, respectively, with thiophene-2-carbaldehyde to form 2-phenyl-5-[(thiophen-2-yl)methylidene]-3-{[(E)-(thiophen-2-yl)methylidene]amino}-3,5-dihydro-4H-imidazol-4-one, C19H13N3OS2, (V), which exhibits orientational disorder in only one of its thienyl groups, and with methanol to give methyl (2Z)-2-(benzoylamino)-3-(thiophen-2-yl)prop-2-enoate, C15H13NO3S, (VI). There are no direction-specific intermolecular interactions in the crystal structure of the triclinic polymorph of (I), but the molecules of (II) are linked by two independent C-H···O hydrogen bonds to form C2(2)(14) chains. Compounds (III) and (IV) both form centrosymmetric R2(2)(10) dimers built from N-H···O hydrogen bonds, while compound (V) forms a centrosymmetric R2(2)(10) dimer built from C-H···O hydrogen bonds. In the structure of compound (VI), a combination of N-H···O and C-H···π(arene) hydrogen bonds links the molecules into sheets. Comparisons are made with some similar compounds.

Crystal structure of 2-methyl-4-[(thio-phen-2-yl)methyl-idene]-1,3-oxazol-5(4H)-one

The asymmetric unit of the title compound, C9H7NO2S, contains two crystallographically independent mol-ecules (A and B). Both mol-ecules are almost planar [maximum deviations = 0.047 (1) and 0.090 (1) Å, respectively, for the S atoms] with the oxazole and thio-phene rings being inclined to one another by 2.65 (16)° in mol-ecule A and by 4.55 (15)° in mol-ecule B. In the crystal, the individual mol-ecules are linked via C-H⋯O hydrogen bonds, forming -A-B-A-B- chains along the [10-1] direction. The chains are linked via C-H⋯π and π-π inter-actions [inter-centroid distances = 3.767 (2) and 3.867 (2) Å] involving inversion-related oxazole and thio-phene rings in both mol-ecules, forming a three-dimensional structure.