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Synthesis 1997; 1997(10): 1140-1142
DOI: 10.1055/s-1997-1328
short paper
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A New Synthetic Approach to Indazole Synthesis

Pier Giovanni Baraldi1 , Barbara Cacciari2 , Giampiero Spalluto2 , Romeo Romagnoli2 , Giovanni Braccioli2 ,  Naser Zaid2 , Maria J. Pineda de las Infantas3
  • 1Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17/19, I-44100, Ferrara, Italy, Fax +39(532)29112965
  • 2Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17/19, I-44100, Ferrara, Italy
  • 3Departamento de Química Orgànica y Farmacéutica, Facultad de Farmacía, Campus de Cartuja s/n, 18071 Granada, Spain
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Publication History

Publication Date:
31 December 2000 (online)

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Stobbe condensation of 3-alkyl- or aryl-4-formylpyrazoles 3a-f with diethyl succinate in the presence of potassium t-butoxide, followed by intramolecular ring closure (Ac2O-NaOAc), afforded the corresponding indazole derivatives 5a-f in 65-85% overall yield. These compounds are good starting materials for transformation to biologically active molecules, such as new pyrazole analogs of the left-hand segment of the potent natural antineoplastic agent CC-1065.

4-formyl pyrazoles - indazoles - Stobbe condensation - diethyl succinate - electrocyclic ring closure