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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
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Publication Date:
31 December 2000 (online)

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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