A New Straightforward Formation of Aminopyrazoles from Isocyanides

Valérie Atlan; Christophe Buron; Laurent El Kaïm

doi:10.1055/s-2000-6563

Synlett 2000; 2000(4): 489-490
DOI: 10.1055/s-2000-6563

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A New Straightforward Formation of Aminopyrazoles from Isocyanides

Valérie Atlan^* , Christophe Buron, Laurent El Kaïm

^*Laboratoire Chimie et Procédés, Ecole Nationale Supérieure de Techniques Avancées, 32 boulevard Victor, 75015 Paris, France; Fax 33.01.45.52.83.22; E-mail: elkaim@ensta.fr

Abstract

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The reaction of α-halogenoketone hydrazones with isocyanides and sodium carbonate leads to a new formation of 5-aminopyrazole derivatives. This reaction probably involves in situ azoalkene formation followed by a [4+1] cycloaddition with isocyanide. Good yields are obtained for electron deficient ketone hydrazones such as ethyl bromopyruvate hydrazones; this reaction was successfully applied to the one pot synthesis of an antihistaminic pyrazole.

hydrazones - isocyanides - pyrazoles - [4+1] cycloaddition

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