N-(Acyloxy)phthalimides as Redox-Active Esters in Cross-Coupling Reactions

Recent years have witnessed a resurgence of novel, efficient and practical protocols for radical-mediated cross-coupling reactions involving N-(acyloxy)phthalimides (NHPI esters) as redox-active esters. After the initial discovery of the redox-active properties of NHPI esters, exciting examples of SET-based cross-coupling reactions under thermal or photolytic conditions leading to diverse C-X (X=C, B, Si, Se, S) bonds have been published. The operational simplicity and broad applicability exhibited in redox-active NHPI ester-based cross-couplings bode well for their widespread adoption. The review presented herein covers all the recent developments in the field of redox-active ester (RAE)-based cross-couplings since the initial discovery. Depending on the conditions employed the reactions have been categorized into photoinduced and non-photoinduced cross-couplings with representative examples and insightful mechanistic discussions.