O. G. Khudina, Y. Burgart, E. V. Shchegol'kov
Jul 11, 2009
Citations
0
Influential Citations
12
Citations
Journal
Russian Journal of Organic Chemistry
Abstract
Steric structure of fluorinated 2-arylhydrazono-3-oxo esters was studied by 1H, 19F, and 13C NMR spectroscopy and X-ray analysis. It was found that these compounds in the crystalline state and in solutions in acetone-d6, DMSO-d6, and CDCl3 exist as Z isomers with the ester fragment involved in intramolecular hydrogen bond with the hydrazone NH proton. Exceptions are alkyl 2-arylhydrazono-4,4-difluoro-3-oxobutanoates which exist in acetone-d6 as mixtures of Z and E isomers, the former prevailing. Unlike fluorinated analogs, ethyl 2-(4-methylphenyl)hydrazono-3-oxobutanoate in crystal has the structure of E isomer in which intramolecular hydrogen bond is formed between the NH proton and acetyl carbonyl group. The same compound in acetone-d6, DMSO-d6, and CDCl3 gives rise to a mixture of Z and E isomers, the latter prevailing.