Author: Noshiranzadeh Nader Ramazani Ali
Publisher: Taylor & Francis Ltd
ISSN: 1042-6507
Source: Phosphorus, Sulfur, and Silicon and the Related Elements, Vol.183, Iss.5, 2008-05, pp. : 1109-1115
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Abstract
Reactions of sterically congested stabilized phosphorus ylides with phenylhydrazine in the presence of silica gel powder in solvent-free conditions proceed smoothly at 100°C to afford dialkyl 2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)-2-butenedioates in good yields. The structures of the products were deduced from their IR, 1H NMR, and 13C NMR spectra. The mass spectra of these compounds displayed molecular ion peaks at the appropriate z values. The 1H NMR (CDCl3) spectra of the compounds show the presence of two estereoisomers (E and Z) for each pyrazoles. The relative population of E and Z isomers were determined via their 1H NMR spectra The reaction is fairly stereoselective.
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