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Keywords:

  • one-pot approach;
  • 2,4-dioxo-3,4-diarylbutanoates;
  • Claisen condensation;
  • Knorr reaction;
  • triarylpyrazole-3-carboxylates

Abstract

A one-pot approach to ethyl 1,4,5-triaryl-1H-pyrazole-3-carboxylates has been developed in moderate to high yields. The tert-BuOLi-mediated Claisen condensation of 1,2-diarylethanones and ethyl oxalyl chloride efficiently provided the enolized lithium salts of ethyl 2,4-dioxo-3,4-diarylbutanoates, which in situ reacted with arylhydrazine hydrochlorides via a hydrochloric acid-promoted Knorr reaction to produce the exquisite triarylpyrazole-3-carboxylates. The procedure promises a convenient access to this highly crowded framework for drug discovery.