D. Pinto, Artur M. S. Silva, J. Cavaleiro
Aug 13, 1999
Citations
0
Influential Citations
47
Citations
Journal
Tetrahedron
Abstract
Abstract 3-(2-Benzyloxy-6-hydroxyphenyl)-5-styrylpyrazoles 7a-e were prepared from the reaction of 2-styrylchromones and hydrazine hydrate. 3-(2-Benzyloxy-6-hydroxyphenyl)-5-(2-phenylethyl)-pyrazoles 8a,d,e and 3-(2-benzyloxy-β,6-dihydroxystyryl)-5-aryl-2-pyrazolines 9a-e were also obtained as by-products. The crystal and molecular structure of two 3-(2-benzyloxy-6-hydroxyphenyl)-5-styrylpyrazoles 7a,b have been determined by X-Ray analysis. Although the substitution of an hydrogen by a methyl group on the double bond of the styryl moiety seems to be a minor perturbation, it produces drastic changes in the crystal packing where only one conformer is present. The OH group is involved as donor of an intramolecular hydrogen bond and the NH group is responsible for the formation of chains via intermolecular hydrogen bonds.