C70 Fullerene Catalyzed Photoinduced Aerobic Oxidation of Benzylamines to Imines and Aldehydes

Selective Construction of C-S/S-N Bonds from N-Substituted O-Thiocarbamates and Indoles under Transition-Metal-Free Conditions

A method for the selective construction of S-N/C(sp2)-S bonds using N-substituted O-thiocarbamates and indoles as substrates is reported. This protocol features good atom utilization, mild conditions, short reaction time, and wide substrate scope, which can provide a convenient path for the functionalization of indoles. In addition, the reaction could be scaled up on gram scale, showing potential application value in industry synthesis.

Metal-Free Visible-Light Induced Oxidative Cleavage of C(sp3 )-C, and C(sp3 )-N Bonds of Nitriles, Alcohols, and Amines

Selective cleavage of unstrained (sp3 ) C-C/ C-N bonds under mild conditions is highly challenging due to the higher bond dissociation energy. A visible light mediated metal-free oxidative dehomologation of aryl acetonitriles, primary alcohols and diols to carboxylic acids via organophotocatalyzed C(sp3 )-CN, C(sp3 )-C(OH) bond cleavage is reported. Notably, this methodology was further extended towards selective synthesis of aldehydes via deamination of both primary as well as secondary amines. This mild protocol features wide array of substrate variation with excellent functional group tolerance, preparative-scale synthesis, and operational simplicity. Possible mechanisms for these transformations were demonstrated through a series of control experiments.

Visible light-induced metal-free chemoselective oxidative cleavage of benzyl C-heteroatom (N, S, Se) bonds utilizing organoboron photocatalysts

The oxidation process is widely explored and used to synthesize diverse organic chemicals. Herein, a unified metal-free photooxidative platform for the cleavage of C-heteroatom bonds has been developed. In these reactions, the aminoquinolate diarylboron (AQDAB) complex is utilized as the photocatalyst, instigating the oxidation process induced by visible light. The cleavage of C-heteroatom bonds can be achieved chemoselectively, affording the formal carbonylation product of C-N, C-S, and C-Se bonds. This method provides a channel for connecting amines, thiols, or selenides with the carbonyl compounds directly, broadening the potential applications of oxidation as a synthetic tool.

Versatile Synthesis of Symmetric and Unsymmetric Imines via Photoelectrochemical Catalysis: Application to N-Terminal Modification of Phenylalanine

A strategy that combines electrochemical synthesis and photoredox catalysis was reported for the efficient synthesis of imines. This approach was demonstrated to be highly versatile in producing various types of imines, including symmetric and unsymmetric imines, by exploring the impact of different substituents on the benzene ring of the arylamine. Additionally, the method was specifically applied to modify N-terminal phenylalanine residues and was found to be successful in the photoelectrochemical cross-coupling reaction between NH2 -Phe-OMe and aryl methylamines, leading to the synthesis of phenylalanine-containing imines. Therefore, this technique would present a convenient and efficient platform for synthesizing imines, with promising applications in chemical biology, drug development, and organic synthesis.

Innovative green oxidation of amines to imines under atmospheric oxygen

In recent years, the development of environmentally benign molecular construction methods has been of great importance, and especially, resource recycling, high atomic efficiency, and low environmental impact are in high demand. From this point of view, attention has also been focused on the development of one-pot synthesis of pharmaceuticals and functional molecules. Imines are excellent synthetic intermediates of these useful molecules, and the environmentally friendly oxidative synthesis of imines from amines has been energetically developed using oxygen (or air), which is abundantly available on the Earth, as an oxidant. This review focuses on the latest innovative and green oxidation systems of amines to imines under atmospheric oxygen, and their application to one-pot/eco-friendly and sustainable synthesis of pharmaceuticals and functional molecules. In particular, catalytic systems that activate molecular oxygen are categorized and described in detail as transition metal catalytic systems, photoirradiated catalytic systems, and organocatalytic systems.

Photocatalytic Cleavage of C(sp3 )-N Bond in Trialkylamines to Dialkylamines and Olefins

Development of a new and green strategy for C(sp³ )-N bond cleavage is very interesting. Herein, photocatalytic cleavage of the C(sp³ )-N bond of trialkylamines was achieved, with concurrent formation of dialkylamines and olefins. It was found that a rationally designed 2D-Bi₂ WO₆ @1D-LaPO₄ heterostructure was very efficient for the reaction due to its high light collection efficiency and unique catalytic properties. The strategy could be used for different trialkylamines, including triethylamine, tri-n-propylamine, and ethyl-di-isopropylamine. The mechanistic investigation indicated that the catalyst with heterostructure was not only favorable for charge carrier separation but also rendered excited electrons with high reduction capacity. This work opens a way for C(sp³ )-N bond cleavage of trialkylamines.

Visible Light-Induced Aerobic Oxidative Dehydrogenation of C-N/C-O to C=N/C=O Bonds Using Metal-Free Photocatalysts: Recent Developments

Performing synthetic transformation using visible light as energy source, in the presence of a photocatalyst as a promoter, is currently of high interest, and oxidation reactions carried out under these conditions using oxygen as the final oxidant are particularly convenient from an environmental point of view. This review summarizes the recent developments achieved in the oxidative dehydrogenation of C-N and C-O bonds, leading to C=N and C=O bonds, respectively, using air or pure oxygen as oxidant and metal-free homogeneous or recyclable heterogeneous photocatalysts under visible light irradiation.

1T-MoS2 catalysed reduction of nitroarenes and a one-pot synthesis of imines

An expedient synthesis of aromatic amines and imines via the reduction of nitroaromatics using 1T-MoS2 as a heterogeneous catalyst.

Type I 'Lighted Metal-free' Photosensitizing Assemblies of Phenazine for Aerobic Oxidative Transformations

Highly photostable supramolecular photosensitizing 'lighted metal-free' assemblies of DPZ-Th have been developed which show strong absorption in the visible region and excellent electron transportation potential from donor to acceptor units. The as-prepared assemblies of DPZ-Th activate aerial oxygen to generate Type I reactive oxygen species (ROS) under visible-light irradiation in mixed aqueous media. Owing to these properties, the as-prepared DPZ-Th assemblies exhibit high photocatalytic activity in catalyzing the aerobic oxidative coupling of benzylamines and synthesis of quinazolines. Various spectroscopic studies support the participation of Type I reactive species in the reaction mechanism. The 'pure' oxygen environment was not needed for carrying out these transformations and all the reactions proceed very well under aerial conditions to furnish the desired products in high yields.

Copper-catalyzed deaminative alkynylation of secondary amines with alkynes: selectivity switch in the synthesis of diverse propargylamines

The copper-catalyzed selective deamination and alkynylation of the unsymmetrical secondary amines with terminal alkynes was reported with a broad substrate scope and excellent functional compatibility.