Metal-Free Generation of Phosphorus-Centered Radicals for the Synthesis of Phosphorus-Based Heterocycles: A Personal Account

Abstract

This short review describes our recent efforts to generate phosphorus-based radicals under metal-free conditions and their use as key intermediates for the synthesis of phosphorus-based heterocycles. In this regard, the synthesis of benzo[b]phosphole oxides and 6-phosphorylated phenanthridines will be reported. While the synthesis of the former lies in the use of photoredox catalysis, the latter have been obtained through the use of an electron donor–acceptor complex from the combination of diphenyliodonium ion with triethylamine. Mechanistic aspects of both reaction types are discussed based on detailed mechanistic studies including electron paramagnetic resonance, UV–vis spectroscopic, NMR and steady-state photolysis experiments. 1 Introduction 2 Photoredox Catalysis for the Generation of Phosphinoyl Radicals 3 Generation of Phosphinoyl Radicals through the Formation of EDA Complexes 4 Conclusions