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Synlett 2000; 2000(3): 353-354
DOI: 10.1055/s-2000-6526
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Trichloroacylhydrazones: New Straightforward Preparation of Pyrazoles from Keto Esters

Laurent El Kaim* , Stephane Lacroix
  • *Laboratoire Chimie et Procédés, Ecole Nationale Supérieure de Techniques Avancées, 32 boulevard Victor, 75015 Paris, France; Fax +33 1 45 52 83 22; E-mail: elkaim@ensta.fr
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Publication Date:
31 December 2000 (online)

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Trichloroacylhydrazones react smoothly at room temperature with β-keto esters to form pyrazoles in high yield. A weak base such as sodium carbonate is necessary for the process to start and best yields are obtained in aprotic polar solvents; a possible mechanism involving chlorine transfer is proposed for this reaction.

hydrazones - trichloroacyl - keto esters - pyrazoles

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