61490-96-8Relevant academic research and scientific papers
New "green" approaches to the synthesis of pyrazole derivatives
Corradi, Anna,Leonelli, Cristina,Rizzuti, Antonino,Rosa, Roberto,Veronesi, Paolo,Grandi, Romano,Baldassari, Sara,Villa, Carla
, p. 1482 - 1495 (2007/12/27)
A novel approach to the synthesis of pyrazole derivatives from tosylhydrazones of α,β-unsaturated carbonyl compounds possessing a β-hydrogen is proposed, exploiting microwave (MW) activation coupled with solvent free reaction conditions. The cycloaddition was studied on three ketones (trans-4-phenyl-3-buten-2-one, β-ionone and trans-chalcone). The corresponding 3,5-disubstitued-1H-pyrazoles were obtained in high yields and after short reaction times. In order to simplify and point out the green chemistry features of the method, a further improvement was achieved under the same catalytic conditions with a "one pot" synthesis of these heterocyclic compounds, starting directly from their carbonyl precursors via tosylhydrazones generated in situ. For an exhaustive study, the dielectric properties of the solid reaction mixtures were also measured, in order to obtain input data for the numerical simulation of their heating behaviour in the single mode MW cavity which was used for experimental work. In order to supply a valid methodology and tool for measuring the environmental impact, a comparative study between the synthetic route proposed and the classical synthetic route has been carried out.
REACTIONS OF SODIUM SALTS OF TOSYLHYDRAZONE COMPOUNDS WITH SILVER CHROMATE. FORMATION OF INDAZOLE, PYRAZOLE, AND BENZONITRILE DERIVATIVES.
Saito,Toda,Mukai
, p. 1567 - 1569 (2007/10/02)
Tropone tosylhydrazone sodium salt was allowed to react with silver chromate to give 2-tosyl-2H-indazole. The reaction is thought to proceed through the cyclization of the hydrazyl radical intermediate. Under the same conditions, sodium salts of m-nitrobenzaldehyde tosylhydrazone (5), benzylideneacetone tosylhydrazone derivatives (7a and 7b), and beta -ionone tosylhydrazone (9) reacted to yield m-nitrobenzonitrile from 5 and pyrazole derivatives from 7a, b, and 9, respectively. m-Nitrobenzonitrile is formed by homolytic fission of nitrogen-nitrogen bond of 5. Formation of the pyrazole derivatives can be explained by intramolecular 1,3-dipolar additions of the corresponding diazo intermediates.
