SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

Synthesis of gem-Difluorohomoallyl Amines via a Transition-Metal-Free Defluorinative Alkylation of Benzyl Amines with Trifluoromethyl Alkenes

A mild and transition-metal-free defluorinative alkylation of benzyl amines with trifluoromethyl alkenes is reported. The features of this protocol are easy-to-obtain starting materials, a wide range of substrates, and functional group tolerance as well as high atom economy, thus offering a strategy to access a variety of gem-difluorohomoallyl amines, which are extensively distributed in pharmaceuticals and bioactive agents, with excellent chemoselectivity. The primary products can be further transformed to a diversity of 2-fluorinated pyrroline compounds.

Para-selective nitrobenzene amination lead by C(sp2)-H/N-H oxidative cross-coupling through aminyl radical

Arylamines, serving as crucial building blocks in natural products and finding applications in multifunctional materials, are synthesized on a large scale via an electrophilic nitration/reduction sequence. However, the current methods for aromatic C-H amination have not yet attained the same level of versatility as electrophilic nitration. Here we show an extensively investigated transition metal-free and regioselective strategy for the amination of nitrobenzenes, enabling the synthesis of 4-nitro-N-arylamines through C(sp2)-H/N-H cross-coupling between electron-deficient nitroarenes and amines. Mechanistic studies have elucidated that the crucial aspects of these reactions encompass the generation of nitrogen radicals and recombination of nitrobenzene complex radicals. The C(sp2)-N bond formation is demonstrated to be highly effective for primary and secondary arylamines as well as aliphatic amines under mild conditions, exhibiting exceptional tolerance towards diverse functional groups in both nitroarenes and amines (>100 examples with yields up to 96%). Notably, this C(sp2)-H/N-H cross-coupling exhibits exclusive para-selectivity.

Nitroarenes and nitroalkenes as potential amino sources for the synthesis of N-heterocycles

Nitro-compounds are one of the cheapest and most readily available materials in the chemical industry and are commonly utilized as versatile building blocks. Previously, the synthesis of N-heterocycles was largely based on anilines. The utilization of nitroarenes and nitroalkenes for the synthesis of N-heterocyclic compounds can save at least one step, however, as compared to anilines. Thus, considerable attention has been paid to nitroarenes and nitroalkenes as new potential amino sources. Significant progress has been made in the reductive cyclization of nitroarenes or nitroalkenes to access various N-heterocycles in recent years. Herein, we comprehensively summarize the recent progress in the construction of N-heterocycles using nitroarenes and nitroalkenes as potential amino sources. The compatibility of the reaction substrate, its mechanism, applications, advantages, and limitations in this field are also discussed in detail.

Photoinduced Oxygen Transfer Using Nitroarenes for the Anaerobic Cleavage of Alkenes

Herein we report the anaerobic cleavage of alkenes into carbonyl compounds using nitroarenes as oxygen transfer reagents under visible light. This approach serves as a safe and practical alternative to mainstream oxidative cleavage protocols, such as ozonolysis and the Lemieux-Johnson reaction. A wide range of alkenes possessing oxidatively sensitive functionalities underwent anaerobic cleavage to generate carbonyl derivatives with high efficiency and regioselectivity. Mechanistic studies support that the transformation occurs via direct photoexcitation of the nitroarene followed by a nonstereospecific radical cycloaddition event with alkenes. This leads to 1,3,2- and 1,4,2-dioxazolidine intermediates that fragment to give the carbonyl products. A combination of radical clock experiments and in situ photoNMR spectroscopy revealed the identities of the key radical species and the putative aryl dioxazolidine intermediates, respectively.

The Coupling of Carbon and Nitrogen Substituents with Nitroarenes：Vicarious Nucleophilic Substitution of Hydrogen in Nitroarenes

Abstract:

In recent years, nitroarenes have been extensively exploited as green, efficient electrophilic arylation reagents used in a variety of organic syntheses. Transition-metal-free cross-coupling reactions and vicarious nucleophilic substitution (VNS) have become practical and reliable synthetic methods to access momentous func-tionalized organic compounds. Thus, the introduction of various substituents into nitroarenes has attracted considerable attention as important synthetic approach-es due to their simplicity and practicality. In this review, we comprehensively summarize the coupling of several carbon and nitrogen substituents with ni-troarenes via nucleophilic substitution under mild conditions, followed by the ap-plication of these transversions in the construction of carbon and heterocyclic rings.

Arylations with Nitroarenes for One-Pot Syntheses of Triaryl-methanols and Tetraarylmethanes

Triarylmethanols are well-known core structures in natural products and pharmacologically relevant compounds. In general, transition metal-based catalysts or highly reactive organometallics are employed for the synthesis of these compounds. Herein,...