Functionalized 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(4-substituted-phenyl)prop-2-en-1-ones: synthetic pathway, and the structures of six examples

Abstract

Five examples each of 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-ones and the corresponding 1-(4-azidophenyl)-3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones have been synthesized in a highly efficient manner, starting from a common source precursor, and structures have been determined for three examples of each type. In each of 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, C28H21ClN2O3, (Ib), the isomeric 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, (Ic), and 3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C32H24N2O3, (Ie), the molecules are linked into chains of rings, formed by two independent C—H...O hydrogen bonds in (Ib) and by a combination of C—H...O and C—H...π(arene) hydrogen bonds in each of (Ic) and (Ie). There are no direction-specific intermolecular interactions in the structure of 1-(4-azidophenyl)-3-[3-methyl-5-(2-methylphenoxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C26H21N5O2, (IIa). In 1-(4-azidophenyl)-3-[5-(2,4-dichlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C25H17Cl2N5O2, (IId), the dichlorophenyl group is disordered over two sets of atomic sites having occupancies 0.55 (4) and 0.45 (4), and the molecules are linked by a single C—H...O hydrogen bond to form cyclic, centrosymmetric R22(20) dimers. Similar dimers are formed in 1-(4-azidophenyl)-3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C29H21N5O2, (IIe), but here the dimers are linked into a chain of rings by two independent C—H..π(arene) hydrogen bonds. Comparisons are made between the molecular conformations within both series of compounds.

Keywords

• synthesis
• substituted pyrazoles
• chalcones
• crystal structures
• disorder
• molecular conformation
• hydrogen boding
• supramolecular assembly