The past decade has witnessed the emergence of N-(acyloxy)phthalimides (NHPI esters) and its derivatives at the forefront of synthetic methods facilitating the construction of diverse molecular frameworks from the readily available carboxylic acid feedstock. The NHPI esters are predisposed to undergo reductive fragmentation via a single electron transfer (SET) process under thermal, photochemical, or electrochemical conditions to generate the corresponding carbon-or nitrogencentered radicals that participate in a multitude of synthetic transformations to forge carbon−carbon and carbon−heteroatom bonds. The chemistry involving NHPI esters has received broad applicability not only in well-designed cascade annulations but also in medicinal chemistry and natural product synthesis. This comprehensive Review, broadly categorized according to the nature of the bond formation, details the progress made in this field since the initial discovery by providing representative examples with mechanistic details, with an emphasis on challenges and future directions.

An organophotoredox-catalyzed reduction/addition/oxidation cascade of N-protected maleimides and N-(acyloxy)phthalimides is documented. The mild and efficient redox-neutral process involves hitherto unknown Giese-type addition of aryloxy-alkyl radicals on the N-protected maleimides and...

In the last decade, visible light photoredox catalysis promoting radical‐based organic transformations has received enormous synthetic applicability, as they allow unfolding of site‐selective reactivities under mild reaction conditions. Moreover, the photoredox transformations utilizing organic dyes as photocatalysts are attractive with regard to low cost, less toxicity, easy availability and high functional group tolerance. The organophotoredox‐catalyzed reaction technologies enabling direct, efficient and selective late‐stage functionalization of various heterocycles leading to the formation of various C−C and C−X (X=N, P, O, S, Se, Br) bonds have emerged at the forefront of synthetic methodologies available to synthetic chemists. This minireview summarizes the developments made in the last five years in the field of late‐stage functionalization of heterocycles governed by various organophotocatalysts and intends to provide the readers a comprehensive overview of this research field with representative examples and mechanistic insights.

Synthetic methods enabling late-stage modification of heterocycles hold tremendous importance in the pharmaceutical and agrochemical industry and drug discovery. Accordingly, efficient, functional group tolerant and selective late-stage alkylation of valuable molecular entities is of enormous significance and well-acknowledged in medicinal chemistry. Radical alkylation of heteroarenes employing carboxylic acids as the alkyl radical precursor represents one of the most direct ways of CÀ H functionalizations of heterocycles. Recently, the field has undergone a revolutionary development especially with regard to the generation of alkyl radicals under much milder conditions. In this regard N-(acyloxy)phthalimides (NHPI esters) have emerged as a suitable precursor of a diverse set of alkyl radicals allowing formal CÀ H alkylation of not only N-heteroarenes but a diverse set of non-aromatic heterocycles under visible light photocatalysis or electrochemical conditions. This review delineates all these discoveries and provides readers a comprehensive overview of this rapidly expanding field.

We disclose a transition-metal-free NaI/PPh3-mediated direct C–H alkylation of azauracils using N-(acyloxy)­pthalimides (NHPIs) as readily available alkyl surrogates under visible light irradiation. Detailed mechanistic studies reveal formation of a photoactivated electron donor–acceptor (EDA) complex between NaI/PPh3, TMEDA, and alkyl NHPI ester and establish the crucial role of TMEDA in increasing the activity of the photoredox system. The reaction demonstrates a broad scope, scalability, and appreciable functional group tolerance. A variety of azauracils are shown to undergo alkylation by primary, secondary, and tertiary NHPI esters under mild conditions, furnishing the desired products in good to excellent yields.