The Cleavage of p-Nitrophenylhydrazones and Semicarbazones with Ammonium Chlorochromate Adsorbed on Alumina Under Non-Aqueous Conditions
摘要:
Deprotection of p-nitrophenylhydrazones and semicarbazones to their parent aldehydes and ketones in good yields has been carried out by using ammonium chlorochromate adsorbed on alumina under mild conditions.
Synthesis of Substituted 1H-Indazoles from Arynes and Hydrazones
摘要:
The 1H-indazole skeleton can be constructed by a [3 + 2] annulation approach from arynes and hydrazones. Under different reaction conditions, both N-tosylhydrazones and N-aryl/alkylhydrazones can be used to afford a variety of indazoles. The former reaction affords 3-substituted indazoles either via in situ generated diazo compounds or through an annulation/elimination process. The latter reaction leads to 1,3-disubstituted indazoles likely through an annulation/oxidation process. The reactions operate under mild conditions and can accommodate aryl, vinyl, and less satisfactorily, alkyl groups.
Kinetics and mechanism of the reaction of substituted phenylhydrazones with thallium(III) acetate. Reactions of mercury(II) acetate with nitrogen compounds. Part 8
作者:Richard N. Butler、Gerard J. Morris、Anne M. O'Donohue
DOI:10.1039/p29810001243
日期:——
The reaction of substituted phenylhydrazones with thallium(III) acetate in acetic acid involved an electrophilic attack at the hydrazone amino-NH moiety giving an intermediate which is attacked by solvent at the methine carbon. The Hammett ρ values for substituents in the methine and the N-phenyl rings were –1.05 and –3.6, respectively. Activation thermodynamic parameters ΔEa 17.9, ΔHa 17.2 kcal mol–1
A highly efficient Pt-catalyzed [3,3] sigmatropic rearrangement/cyclization cascade of N-propargylhydrazones is reported. The process provides expedient access to a variety of highly functionalized pyrazoles. The substrate has good substituted group compatibility, and the bioactive 3-CF3 pyrazoles could be synthesized easily with this method.
Deprotection of p-nitrophenylhydrazones and semicarbazones to their parent aldehydes and ketones in good yields has been carried out by using ammonium chlorochromate adsorbed on alumina under mild conditions.
Synthesis of Substituted 1<i>H</i>-Indazoles from Arynes and Hydrazones
作者:Pan Li、Chunrui Wu、Jingjing Zhao、Donald C. Rogness、Feng Shi
DOI:10.1021/jo202598e
日期:2012.4.6
The 1H-indazole skeleton can be constructed by a [3 + 2] annulation approach from arynes and hydrazones. Under different reaction conditions, both N-tosylhydrazones and N-aryl/alkylhydrazones can be used to afford a variety of indazoles. The former reaction affords 3-substituted indazoles either via in situ generated diazo compounds or through an annulation/elimination process. The latter reaction leads to 1,3-disubstituted indazoles likely through an annulation/oxidation process. The reactions operate under mild conditions and can accommodate aryl, vinyl, and less satisfactorily, alkyl groups.