Copper-catalyzed intra- and intermolecular carbonylative transformation of remote C(sp3) H bonds in N-fluoro-sulfonamides

Divergent synthesis of carbamates and N-methyl carbamates from dimethyl carbonate and nitroarenes with Mo(CO)6 as a multiple promoter

Dialkyl carbonates are green and versatile reagents that can be used in alkylation and alkoxycarbonylation reactions. Herein, we disclosed a reductive methoxycarbonylation of aromatic nitro compounds with dimethyl carbonate for the construction of diverse carbamates and N-methyl carbamates. Using Mo(CO)6 as a multiple promoter, different nitroarenes were smoothly transformed into the corresponding carbamates in yields between 27 and 94% using DMC as both solvent and reagent. It is worth noting that the choice of different bases allowed the desired products to be controlled: K3PO4 favoured the formation of carbamates as the primary product, whereas DBU facilitated the formation of N-methyl carbamates as the main product.

Direct synthesis of phthalimides via palladium-catalysed double carbonylation of o-dihaloarenes with nitroarenes

The direct carbonylation of readily available nitro compounds is more attractive and straightforward than the use of traditional amines as nucleophiles. Herein, a practical palladium-catalysed double carbonylation of nitroarenes with o-dihaloarenes has been developed for the construction of various N-aryl phthalimides. Key to the success of this transformation is the use of Mo(CO)6, which acts as both a reducing agent and a solid carbonyl source. A wide range of nitroarenes and o-dihaloarenes as well as o-iodobenzoic acids reacted smoothly to give phthalimides in 27-94% yields.

Piperidine Derivatives: Recent Advances in Synthesis and Pharmacological Applications

Piperidines are among the most important synthetic fragments for designing drugs and play a significant role in the pharmaceutical industry. Their derivatives are present in more than twenty classes of pharmaceuticals, as well as alkaloids. The current review summarizes recent scientific literature on intra- and intermolecular reactions leading to the formation of various piperidine derivatives: substituted piperidines, spiropiperidines, condensed piperidines, and piperidinones. Moreover, the pharmaceutical applications of synthetic and natural piperidines were covered, as well as the latest scientific advances in the discovery and biological evaluation of potential drugs containing piperidine moiety. This review is designed to help both novice researchers taking their first steps in this field and experienced scientists looking for suitable substrates for the synthesis of biologically active piperidines.

Palladium-Catalyzed and Photoinduced Benzylic C-H Carbonylation/Annulation under Mild Conditions

A Pd-catalyzed and photoinduced benzylic cascade benzylic C-H carbonylation/annulation reaction is realized under mild conditions (35 °C, 2 bar CO). The use of a catalytic amount of base is crucial for the reaction to achieve high yields. The reaction consists of a Pd-catalyzed generation of amidyl radical from O-benzyl hydroxylamide substrates and 1,5-HAT to give a benzylic radical, followed by carbonylation and annulation. Various homophthalimides, which could be readily converted to a number of bioactive compounds, could be obtained with up to 96% yield.

Recent advances in Cu-catalyzed carbonylation with CO

Transition metal-catalyzed carbonylation has emerged as a powerful and versatile strategy for the efficient construction of complicated carbonyl-containing molecules from simple chemical feedstocks in the past decades.

Difluoromethylarylation of α, β- Unsaturated Amides via a Photocatalytic Radical Smiles Rearrangement

A photocatalytic Smiles rearrangement, triggered by radical difluoromethylation of conjugated arylsulfonylated amides, was developed to construct both β-difluoromethyl amide and heterocyclic scaffolds selectively. This transformation features mild conditions and broad...

Electrochemical oxidative cyclization of N-allylcarboxamides: efficient synthesis of halogenated oxazolines

Herein, we reported an efficient and sustainable intramolecular electrochemical cyclization of N-allylcarboxamides for the synthesis of various halogenated oxazolines.

Iron-Catalyzed, Site-Selective Difluoromethylthiolation (-SCF2H) and Difluoromethylselenation (-SeCF2H) of Unactivated C(sp3)-H Bonds in N-Fluoroamides

The iron-catalyzed δ-C(sp³)-H bond difluoromethylthiolation and difluoromethylselenation of aliphatic amides with high site selectivity are reported. Essential to the success is the employment of an amide radical formed in situ to activate the inert C(sp³)-H bond and the utilization of the easily handled PhSO₂SCF₂H and PhSO₂SeCF₂H as coupling reagents under mild conditions. This scalable protocol exhibits a broad substrate scope bearing versatile functional groups. Mechanistic studies indicate that the reaction proceeds through -SCF₂H and -SeCF₂H radical transfer.

Transition-Metal-Free α Csp3 -H Cyanation of Sulfonamides

This report describes the site-selective α-functionalization of sulfonylamide derivatives through the in-situ generation of imine intermediates. The N-F sulfonylamides, which could facilitate the elimination to generate imines, are coupled with TBACN to efficiently and mildly afford α-amino cyanides. Comparing with Strecker reaction, this transformation offers a complementary strategy to efficiently construct α-amino cyanides from direct α C-H functionalization of sulfonylamindes. The reaction is also characterized by broad substrate scope and flash chromatography column free workup. More importantly, the new two-electron pathway to generate imines through manipulation of the leaving group allows us to achieve excellent α site-selectivity.

Recent Advances in Copper-Catalyzed Radical C–H Bond Activation Using N–F Reagents

This Short Review is aimed at giving an update in the area of copper-catalyzed C–H functionalization involving nitrogen-centered radicals generated from substrates containing N–F bonds. These processes include intermolecular Csp3–H bond functionalization, remote Csp3–H bond functionalization via intramolecular hydrogen atom transfer (HAT), and Csp2–H bond functionalization, which might be of potential use in industrial applications in the future.

1 Introduction

2 Intermolecular Csp3–H Functionalization

3 Remote Csp3–H Functionalization

4 Csp2–H Functionalization

5 Conclusion

Redox Neutral Radical-Relay Cobalt Catalysis toward C-H Fluorination and Amination

A redox neutral radical-relay cobalt-catalyzed intramolecular C-H fluorination of N-fluoroamides featuring the in situ formed cobalt fluorides as the latent radical fluorinating agents is reported. Moreover, the reactivity of such a cobalt catalysis could be diverted from C-H fluorination to amination by engineering substrates' conformational flexibility. Preliminary mechanistic studies (UV-vis spectroscopy, cyclic voltammetry studies and DFT calculations, etc.) support the reaction proceeding a redox neutral radical-relay mechanism.

Copper-Catalyzed, N-Directed Csp3-H Trifluoromethylthiolation (-SCF3) and Trifluoromethylselenation (-SeCF3)

A direct and versatile copper-catalyzed trifluoromethylthiolation and trifluoromethylselenation of primary, secondary, and tertiary aliphatic C-H bonds was developed. The reaction provides direct access to molecules containing these emerging moieties in the presence of a wide range of common functional groups and in complex molecular environments.