ABSTRACT A simple, environmentally benign protocol for synthesis of hydrazones from carbonyl compounds and hydrazides has been developed in the presence of meglumine in aqueous-ethanol media at room temperature. The salient features of the present protocol are mild reaction conditions, short reaction time, high yields, operational simplicity, metal-free, applicability toward large-scale synthesis, and biodegradable
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2-C-H Acetoxylation of Diversely Substituted (<i>E</i>
)-1-(Arylmethylene)-2-phenylhydrazines Using PhI(OAc)<sub>2</sub>
as Acetoxy Source at Ambient Conditions
作者:Goutam Brahmachari、Indrajit Karmakar
DOI:10.1002/ejoc.201900994
日期:2019.9.15
It's Simple! Catalyst‐ and additive‐free regioselective direct sp2 C–H acetoxylation of biologically interesting aldehyde hydrazones to access a new series of hydrazone acetates has been achieved. The reaction proceeds at ambient temperature employing PIDA as an acetoxy source.
A highly economical and efficient copper(I)-catalyzed regioselective method for the synthesis of 1,3,4-trisubstituted and 1,3,4,5-tetrasubstituted pyrazoles via [3+2] cycloaddition of hydrazones and nitroolefins has been reported. This process displays excellent applicability with a wide range of substrates under mild conditions.
Syntheses of Formazans Under Phase-Transfer Conditions
作者:Alan A. Katritzky、Sergei A. Belyakov、Dai Cheng、H. Dupont Durst
DOI:10.1055/s-1995-3958
日期:1995.5
Several 1,3,5-triarylformazans were synthesized (42-77%) using a new methodology. Azo-coupling of aryldiazonium salts with arylaldehyde arylhydrazones under mild basic conditions in two-phase liquid-liquid media is efficiently promoted by phase-transfer catalysts (onium salts or dicyclohexano-18-crown-6) at 5-25°C. The condensation of benzaldehyde with phenylhydrazine followed by phase-transfer catalyzed azo-coupling with phenyldiazonium chloride (one-pot procedure) gave 1,3,5-triphenylformazan in a 54% yield without isolation of the intermediate benzaldehyde phenylhydrazone. A double azo-coupling reaction of phenyldiazonium chloride with 9 different CH-active compounds afforded corresponding formazan only in the case of phenylpyruvic acid. Reaction in malonamide gave 3-carbamoyl-1,5-diphenylformazan instead of the expected 1,5-diphenylformazan.
BF3·OEt2 catalyzed base-free regiospecific ring opening of N-activated azetidines with (E)-1-arylidene-2-arylhydrazines
作者:Ranadeep Talukdar
DOI:10.1007/s13738-018-1489-6
日期:2019.1
for synthesis of larger molecules. The first report of regiospecific addition of hydrazones to the benzylic position of aryl azetidines to afford high yields of important hydrazonyl amine derivatives is described herein. A new C–N bond forms in this reaction scheme. The reactions proceed at stellar rates in presence of only 5 mol% of BF3·OEt2 Lewis acid without the need of any base. The reaction requires