Conversion of substituted 5-aryloxypyrazolecarbaldehydes into reduced 3,4′-bipyrazoles: synthesis and characterization, and the structures of four precursors and two products, and their supramolecular assembly in zero, one and two dimensions

The reaction of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde with phenols under basic conditions yields the corresponding 5-aryloxy derivatives; the subsequent reaction of these carbaldehydes with substituted acetophenones yields the corresponding chalcones, which in turn undergo cyclocondensation reactions with hydrazine in the presence of acetic acid to form N-acetylated reduced bipyrazoles. Structures are reported for three 5-aryloxycarbaldehydes and the 5-piperidino analogue, and for two reduced bipyrazole products. 5-(2Chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, C17H13ClN2O2, (II), which crystallizes with Z' = 2 in the space group P1, exhibits orientational disorder of the carbaldehyde group in each of the two independent molecules. Each of 3-methyl-5-(4-nitrophenoxy)-1-phenyl-1H-pyrazole-4-carbaldehyde, C17H13N3O4, (IV), 3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazole-4carbaldehyde, C21H16N2O2, (V), and 3-methyl-1-phenyl-5-(piperidin-1-yl)-1Hpyrazole-4-carbaldehyde, C16H19N3O, (VI), (3RS)-2-acetyl-5-(4-azidophenyl)50-(2-chlorophenoxy)-30-methyl-10-phenyl-3,4-dihydro-10H, 2H-[3,40-bipyrazole] C27H22ClN7O2, (IX) and (3RS)-2-acetyl-5-(4-azidophenyl)-30-methyl-50-(naphthalen- 2-yloxy)-10-phenyl-3,4-dihydro-10H, 2H-[3,40-bipyrazole] C31H25N7O2, (X), has Z' = 1, and each is fully ordered. The new compounds have all been fully characterized by analysis, namely IR spectroscopy, H-1 and C-13 NMR spectroscopy, and mass spectrometry. In each of (II), (V) and (IX), the molecules are linked into ribbons, generated respectively by combinations of C-H center dot center dot center dot N, C-H center dot and C-Cl center dot center dot center dot pi interactions in (II), C-H center dot center dot center dot O and C-H center dot center dot center dot pi hydrogen bonds in (V), and C-H center dot center dot center dot N and C-H center dot center dot center dot O hydrogen bonds in (IX). The molecules of compounds (IV) and (IX) are both linked into sheets, by multiple C-H center dot center dot center dot O and C-H center dot center dot center dot pi hydrogen bonds in (IV), and by two C-H center dot center dot center dot pi hydrogen bonds in (IX). A single C-H center dot center dot center dot N hydrogen bond links the molecules of (X) into centrosymmetric dimers. Comparisons are made with the structures of some related compounds.