Visible-Light-Mediated Photoredox Reactions in the Total Synthesis of Natural Products

Abstract In the last two decades, the field of photoredox catalysis (PRC) has grown impressively with reports of new synthetic methodologies and more efficient versions of known free-radical reactions. The impressive success of visible-light-mediated photoredox catalysis is, in great part, due to its low environmental impact, mild reaction conditions, clean reactions, and inexpensive methodologies. These features have allowed photoredox catalysis to emerge as a powerful tool in the synthesis of natural products; much excellent work was reported between 2011 and 2015. Since 2016, a number of more efficient and impressive total syntheses of natural products featuring photoredox catalysis have been reported. In this review, we summarize the recent synthetic applications of photoredox catalysis in the total synthesis of natural products between 2016 and 2020. 1 Introduction 2 Intermolecular Additions from Functionalized Substrates 2.1 Intermolecular Additions from Alkyl Halides 2.2 Intermolecular Additions from Alcohols and Carboxylic Acids 3 Cyclizations from Functionalized Substrates 3.1 Cyclizations of Carbon-Centered Radicals 3.2 Cyclizations of Nitrogen-Centered Radicals 4 Intramolecular Cyclization from Non-functionalized N–H Bonds 4.1 Type I Radical Cascade 4.2 Type II Radical Cascade 4.3 Type III Radical Cascade 5 Functionalization of Imines and Enamines 6 Cycloadditions 7 Miscellaneous 7.1 Dehalogenation and Reductive Decarboxylation 7.2 Thiyl Radical Promoted Cascade 8 Conclusions and Perspectives