Copper(II) Chloride as an Efficient Reagent for the Dehydrogenation of Pyridazinone Derivatives

Ferenc Csende; Zoltán Szabó; Gábor Bernáth; Géza Stájer

doi:10.1055/s-1995-4079

Synthesis 1995; 1995(10): 1240-1242
DOI: 10.1055/s-1995-4079

short paper

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Copper(II) Chloride as an Efficient Reagent for the Dehydrogenation of Pyridazinone Derivatives

Ferenc Csende, Zoltán Szabó, Gábor Bernáth^* , Géza Stájer

^*Institute of Pharmaceutical Chemistry, Albert Szent-Györgyi Medical University, H-6701 Szeged, POB 121, Hungary

Abstract

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A new procedure is described for the preparation of pyridazinones from 4,5-dihydropyridazinones under mild conditions with CuCl₂ in MeCN via halogenation and spontaneous HCl elimination. For the trans-hexahydrophthalazin-8(1H)-one 1B*, the HCl elimination is five times faster than for the corresponding cis isomer 1B.

A new mild method is described for the dehydrogenation of 4,5-dihydropyridazinones to pyridazinones with CuCl₂

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