A Mild and Efficient Synthesis of Pyrazolo[1,5-a]pyridines Mediated by Triphenylphosphine/Diiodine

Abstract

A synthesis of 2,3-diaryl-substituted pyrazolo[1,5-a]pyridines in moderate to good yields under metal-free and mild conditions is described. The intramolecular cyclization of the oxime substrates is mediated by PPh₃/I₂, which leads directly to pyrazolo[1,5-a]pyridines without the formation of a 2H-azirine intermediate. Various substituents on the aryl rings are compatible with the method.

Key words

pyrazolopyridines - oximes - metal-free synthesis - iodine - triphenylphosphine

Publication History

Received: 28 October 2021

Accepted after revision: 24 November 2021

Accepted Manuscript online:
24 November 2021

Article published online:
20 December 2021

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