Convergent Routes to Pyrroles Exploiting the Unusual Radical Chemistry of Xanthates – An Overview
Received: 15 May 2017
Accepted after revision: 06 June 2017
21 July 2017 (eFirst)
This article is affectionately dedicated to Professor Victor Snieckus on the occasion of his 80th birthday.
Convergent routes to a variety of pyrroles involving radical additions of xanthates are described. Emphasis is placed on reactions leading to the formation of 1,4-diketones or 1,4-ketoaldehydes or their synthetic equivalents, which can then be condensed with ammonia or primary amines in a variation of the classical Paal–Knorr synthesis of pyrroles. The modification of pyrroles by direct radical addition is also discussed.
2 Earlier Routes to Pyrroles
3 The Xanthate Radical Addition–Transfer Process
4 Application to Pyrrole Synthesis
5 Further Variations
6 Direct Modification of Existing Pyrrole Rings
7 Outlook and Perspectives