Search

The C(sp3)–N bond is ubiquitous in natural products, pharmaceuticals, biologically active molecules and functional materials. Consequently, the development of practical and efficient methods for C(sp3)–N bond formation has attracted more and more attention. Compared to the conventional ionic pathway-based thermal methods, photochemical processes that proceed through radical mechanisms by merging photoredox and transition-metal catalyses have emerged as powerful and alternative tools for C(sp3)–N bond formation. In this review, recent advances in the burgeoning field of C(sp3)–N bond formation via metallaphotoredox catalysis have been highlighted. The contents of this review are categorized according to the transition metals used (copper, nickel, cobalt, palladium, and iron) together with photocatalysis. Emphasis is placed on methodology achievements and mechanistic insight, aiming to inspire chemists to invent more efficient radical-involved C(sp3)–N bond-forming reactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Catalytic four‐component radical carbonylation of unactivated alkenes has recently been recognized as a robust protocol for rapid construction of various structurally diverse carbonyl compounds. Given the significance of fluorine‐containing groups, this reaction class has been extensively applied to assembly of a variety of perfluoroalkyl carboxylic acid derivatives by transition metal catalysis. Herein, we report a visible‐light‐driven radical relay 1,2‐perfluoroalkylation aminocarbonylation of unactivated alkenes using CO gas as carbonyl source and 4CzIPN as organic photocatalyst. A wide range of alkenes and amines were well tolerated, providing the valuable β‐perfluoroalkylated amides with generally good yields and high chemoselectivity. [ABSTRACT FROM AUTHOR]

Organic molecules bearing chiral sulfur stereocenters exert a great impact on asymmetric catalysis and synthesis, chiral drugs, and chiral materials. Compared with acyclic ones, the catalytic asymmetric synthesis of thio‐heterocycles has largely lagged behind due to the lack of efficient synthetic strategies. Here we establish the first modular platform to access chiral thio‐oxazolidinones via Pd‐catalyzed asymmetric [3+2] annulations of vinylethylene carbonates with sulfinylanilines. This protocol is featured by readily available starting materials, and high enantio‐ and diastereoselectivity. In particular, an unusual effect of a non‐chiral supporting ligand on the diastereoselectivity was observed. Possible reaction mechanisms and stereocontrol models were proposed. [ABSTRACT FROM AUTHOR]

The construction of an all‐in‐one catalyst, in which the photosensitizer and the transition metal site are close to each other, is important for improving the efficiency of metallaphotoredox catalysis. However, the development of convenient synthetic strategies for the precise construction of an all‐in‐one catalyst remains a challenging task due to the requirement of precise installation of the catalytic sites. Herein, we have successfully established a facile bottom‐up strategy for the direct synthesis of Ni(II)‐incorporated covalent organic framework (COF), named LZU‐713@Ni, as a versatile all‐in‐one metallaphotoredox catalyst. LZU‐713@Ni showed excellent activity and recyclability in the photoredox/nickel‐catalyzed C−O, C−S, and C−P cross‐coupling reactions. Notably, this catalyst displayed a better catalytic activity than its homogeneous analogues, physically mixed dual catalyst system, and, especially, LZU‐713/Ni which was prepared through post‐synthetic modification. The improved catalytic efficiency of LZU‐713@Ni should be attributed to the implementation of bottom‐up strategy, which incorporated the fixed, ordered, and abundant catalytic sites into its framework. This work sheds new light on the exploration of concise and effective strategies for the construction of multifunctional COF‐based photocatalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Ureas are widely used in drugs, materials and catalysts because of their diamide structure, which can form strong hydrogen bonds. Therefore, it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds, especially unsymmetrical ureas. Here, we have disclosed novel and highly efficient three‐component coupling reactions of organic halides, sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas. The reaction features simple and safe operations, broad substrate scopes, and product diversities. It allows the facile synthesis of N‐aryl/vinyl ureas from readily available, user‐friendly feedstocks under mild conditions (27 examples, 36%—98% yields). In addition, this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates (15 examples, 40%—95% yields). The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction. [ABSTRACT FROM AUTHOR]

Vinyldiazo compounds are one of the most important synthons in the construction of a cyclic ring. Most photochemical transformations of vinyldiazo compounds are mainly focusing on utilization of their C═C bond site, while reactions taking place at terminal nitrogen atom are largely unexplored. Herein, a photocatalytic cascade radical cyclization of LBRs with vinyldiazo reagents through sequential B─N/C─N bond formation is described. The reaction starts with the addition of LBRs (Lewis base–boryl radicals) at diazo site, followed by intramolecular radical cyclization to access a wide range of important boron‐handled pyrazoles in good to excellent yields. Control experiments, together with detailed mechanism studies well explain the observed reactivity. Further studies demonstrate the utility of this approach for applications in pharmaceutical and agrochemical research. [ABSTRACT FROM AUTHOR]