Hydrazone

About: Hydrazone is a research topic. Over the lifetime, 4853 publications have been published within this topic receiving 65160 citations. The topic is also known as: hydrazone.

Synthesis, Structure, and Reactivity of a Palladium Hydrazonato Complex: A New Type of Reductive Elimination Reaction To Form C-N Bonds and Catalytic Arylation of Benzophenone Hydrazone.

Abstract: A rare, structurally characterized μ1 ,η1 -hydrazonato complex is a probable intermediate in the Pd-catalyzed N-arylation of hydrazones. Starting from aryl halides the reaction proceeds efficiently and under mild conditions with chelating phosphane ligands (L2 ); even Cs2 CO3 can be used as the base [Eq. (a)]. R=alkyl, aryl, MeCO, MeO; X=Br, I.

Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig olefinations.

Abstract: Tosylhydrazones derived from aryl aldehydes react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity. These reactions occur through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides, with the water-soluble trimethyl phosphate as the byproduct. Similar reactions can also be performed using ethyl diazoacetate; however, high E selectivity was only observed in the presence of LiBr. In this case, the reaction is believed to occur via the phosphonate anion, formed through an Arbuzov reaction. Thus this olefination reaction occurs through a Horner−Wadsworth−Emmons (HWE) reaction but the phosphonate anion is generated under completely base-free conditions.

Copper-mediated synthesis of 1,2,3-triazoles from N-tosylhydrazones and anilines.

Abstract: Significance: Reported is a remarkable synthesis of 1,4-disubstituted and 1,4,5-trisubstituted 1,2,3-triazoles. The reaction of readily available N-tosylhydrazones with anilines is mediated by copper(II) and pivaloic acid. The reaction involves cyclization through C–N and N–N bond formation. This method enables an azide-free access to 1,2,3-triazoles with high efficiency under mild conditions. It exhibits a broad scope tolerating anilines with either electron-withdrawing or -donating groups and a variety of N-tosylhydrazones. More significantly, the two-step synthesis starting from aryl ketones to the desired triazoles can also be executed in a one-pot fashion without compromising the yield. An exclusive high regioselectivity – 1,4-disubstituted or 1,4,5-trisubstituted products – constitutes another advantage of this method. Comment: The most common route to build 1,2,3-triazoles is through Huisgen-type [3+2] cycloadditions. Although numerous methods for the improvement of the Huisgen reaction were reported recently, it is inevitable that an azide (which may sometimes not be readily available) will be involved. To the best of our knowledge, this paper is the first report to synthesize 1,2,3-triazoles without using toxic and potential explosive azide species. A possible tosylhydrazone intermediate (see structure above) of the reaction was proposed and synthesized. Its subsequent treatment with a catalytic amount of copper resulted in the formation of the expected produc. Examples of utilizing heterocyclic amines (e.g., 3-aminopyridine) as substrates in this reaction may be anticipated. Ar1 O

Synthesis, characterization and evaluation of antituberculosis activity of some hydrazones.

Abstract: Several new hydrazone derivatives were prepared by the reaction of some active hydrogen compounds with the diazonium salts of 4-amino-3,5-di/1,3,5-trimethylpyrazoles at 0-5 degrees C. Structures of the new substances were confirmed using UV, IR, 1H NMR, 13C NMR and EI-mass spectral data. In vitro antituberculosis activity of these compounds were tested on Mycobacterium tuberculosis H37Rv at 6.25 microg/ml. Both hydrazone products, ethyl 2-[(3,5-dimethylpyrazole-4-yl)hydrazono]-3-oxobutyrate (3d) and methyl 2-[(3,5-dimethylpyrazole-4-yl)hydrazono]4-methoxy-3-oxobutyrate (3e) showed 29 and 28% inhibition against M. tuberculosis, respectively.