A Novel Reaction of the "Huisgen Zwitterion" with Chalcones and Dienones: An Efficient Strategy for the Synthesis of Pyrazoline and Pyrazolopyridazine Derivatives

• Published in: Angewandte Chemie International Edition Vol. 46; no. 12; pp. 2070 - 2073
• Main Authors: Nair, Vijay, Mathew, Smitha C., Biju, Akkattu T., Suresh, Eringathodi
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.01.2007; WILEY‐VCH Verlag; Wiley
• Subjects: chalcones; Chemistry; Chemistry, Multidisciplinary; nitrogen heterocycles; Physical Sciences; pyrazolines; Science & Technology; synthetic methods; zwitterions; chalcones; MITSUNOBU REACTION; DIETHYL AZODICARBOXYLATE; nitrogen heterocycles; pyrazolines; CARBONYL-COMPOUNDS; zwitterions; INHIBITORS; TRIPHENYLPHOSPHINE; synthetic methods
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.200604025

Two unexpected transformations: The reaction of the Huisgen zwitterion derived from triphenylphosphane and diisopropyl azodicarboxylate (DIAD) with chalcones affords functionalized pyrazolines. In contrast, the reaction with dienones affords pyrazolopyridazines, presumably by Diels–Alder reaction of the initially formed pyrazoline with excess DIAD (see scheme).