Regioselective Synthesis of 4-Nitro- or 4-Chloro-Tetrasubstituted Pyrazoles from Hydrazones and β-Halo-β-nitrostyrenes
作者:Xiaohu Deng、Jimmy T. Liang、Neelakandha S. Mani
DOI:10.1002/ejoc.201301294
日期:2014.1
We report an acid-catalyzed cycloaddition reaction of hydrazones with β-bromo- or β-chloro-β-nitrostyrenes for the regioselectivesynthesis of 4-nitro- or 4-chloro-tetrasubstitutedpyrazoles. Arising from a common 4-halo-4-nitropyrazolidine intermediate, the identity of the pyrazole product formed is dependent on the relative leaving group abilities of the halo and nitro substituents.
1-Methyl(or phenyl)-5-(penta-O-acetyl-d-galacto-pentitol-1-yl)pyrazoles from the reactions of 3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-nitro-d-galacto-hept-1-enitol with aldehyde methyl(or phenyl)hydrazones
作者:Manuel Gómez-Guillén、José María Lassaletta Simon
DOI:10.1016/0008-6215(91)80121-3
日期:1991.3
hept-1-enitol ( 2 ) reacted with aldehydemethyl(or phenyl)hydrazones in refluxing methanol or butyl acetate to give 1-methyl(or phenyl)-5-(penta- O -acetyl- d - galacto -pentitol-1-yl)pyrazoles in good (for 1-methylpyrazoles) or moderate yields (for 1-phenylpyrazoles). The O -deacetylated products were obtained in high yields. A Michael-type adduct was obtained for the reactions of 2 with p -tolualdehyde