Iodide-Catalyzed Synthesis of N-Nitrosamines via C–N Cleavage of Nitromethane

A Radical Activation Strategy for Versatile and Stereoselective N-Glycosylation

Previous N-glycosylation approaches have predominately involved acidic conditions, facing challenges of low stereoselectivity and limited scope. Herein, we introduce a radical activation strategy that enables versatile and stereoselective N-glycosylation using readily accessible glycosyl sulfinate donors under basic conditions and exhibits exceptional tolerance towards various N-aglycones containing alkyl, aryl, heteroaryl and nucleobase functionalities. Preliminary mechanistic studies indicate a pivotal role of iodide, which orchestrates the formation of a glycosyl radical from the glycosyl sulfinate and subsequent generation of the key intermediate, a configurationally well-defined glycosyl iodide, which is subsequently attacked by an N-aglycone in a stereospecific SN2 manner to give the desired N-glycosides. An alternative route involving the coupling of a glycosyl radical and a nitrogen-centered radical is also proposed, affording the exclusive 1,2-trans product. This novel approach promises to broaden the synthetic landscape of N-glycosides, offering a powerful tool for the construction of complex glycosidic structures under mild conditions.

Metal-Free Bisamidation of N-Tosylhydrazones with Carboxylic Acids Promoted by Tetrabutylammonium Iodide and tert-Butyl Hydroperoxide

A versatile reaction between N-tosylhydrazones and carboxylic acids to access bisamides is reported. This metal-free, room-temperature reaction was catalyzed by TBAI, while TBHP served as the oxidant. Broad substrate scope and good functional group tolerance are the key features of the strategy. Subsequent intramolecular N-arylation of suitably substituted bisamides readily afforded functionalized 3-indazolones.

Catalytic Aerobic N-Nitrosation by Secondary Nitroalkanes in Water: A Tandem Diazotization of Aryl Amines and Azo Coupling

Secondary nitroalkanes underwent oxygen-mediated nitro-nitrite isomerization, serving as versatile N-nitrosating agents under aerobic conditions. To capitalize on the newly discovered aerobic nitro-nitrite isomerization phenomenon, a phase-transfer catalysis system employing KSeCN and TBAI was developed, in which the tandem diazotization and azo coupling with nitroalkanes as well as N-nitrosation of amines were accomplished. The current tandem diazotization and azo coupling strategy provides a facile synthesis of areneazo-2-(2-nitro)propane derivatives, a safe synthetic alternative to aryl diazonium salts.

Selective C3-nitrosation of imidazopyridines using AgNO3 as the NO source

We developed a novel method for selective radical nitrosation of imidazo[1, 2-a]pyridine derivatives using AgNO3 as a NO source.

NaI/KI/NH4I and TBHP as powerful oxidation systems: use in the formation of various chemical bonds

In modern organic synthesis, the execution of reactions in the absence of expensive transition metals has received significant attention from the view-point of green chemistry and sustainable development. As a consequence, the combination of MI-TBHP as an oxidation system (M = Na, K, NH4) has opened a new avenue with significant impact for the succinct synthesis of complex heterocycle molecules via the construction of various chemical bonds [C-X (X = C, N, S, O), N-X (X = N, P) and S-N]. This comprehensive review article delineates the progress of recent developments in this emerging area, with an in-depth discussion on the substrate scope, limitations and proper mechanistic underpinnings. We hope this review will highlight the great potential of this MI-TBHP as a powerful oxidation system and inspire researchers to conduct further endeavors in this domain.

3-Thiolated pyrroles/pyrrolines: controllable synthesis and usage for the construction of thiolated fluorophores

Thiolation/cyclization of homopropargylic tosylamides allowed the selective synthesis of 3-thiolated pyrroles and pyrrolines controlled by solvents. Moreover, the desired 3-thiolated pyrroles were readily transformed to organic fluorophores benzothienopyrrole and bisthiolated boron dipyrromethene (S-BODIPY).

Rh(III)-Catalyzed N-Nitroso Directed C-H Arylation for Facile Construction of Diverse N-Hetero Biaryl Compounds

A Rh(III)-catalyzed C-H arylation reaction of N-nitrosoanilines has been developed in which arylboronic acids were used as arylation reagents. It provides an efficient strategy for the synthesis of N-nitroso-[1,1'-biphenyl]-2-amine, which is an important starting material for the synthesis of N-hetero biaryl compounds, such as 2-amine-1,1'-biphenyl, carbazole, phenanthridone. This protocol can be applied to various N-alkyl substituted N-nitrosoanilines and N-nitrosoanilines with substituents on the phenyl ring. Arylboronic acids with both electron-donating and electron-withdrawing groups are tolerated.

Synthesis of Mono-N-Methyl Aromatic Amines from Nitroso Compounds and Methylboronic Acid

The selective synthesis of mono-N-methyl aromatic amines was achieved by the reaction of aromatic nitroso compounds with methylboronic acid promoted by triethylphosphite under transition metal-free conditions. The target compounds are constructed efficiently without overmethylation, under environmentally benign reaction conditions that do not require bases or reductants and therefore are of interest in pharmaceutical, agricultural, and chemical industries.

One-pot synthesis of 1,3,4-oxadiazol-2(3H)-ones with CO2 as a C1 synthon promoted by hypoiodite

A convenient and efficient route has been developed to synthesize 1,3,4-oxadiazol-2(3H)-ones from CO₂, hydrazines and aryl or aliphatic aldehydes. Promoted by hypoiodite (IO^-) generated in situ from KI and oxidant TBHP, the one-pot synthesis could proceed smoothly to afford the desired products in moderate to high yields. Mechanism studies revealed that nitrile imine was an important intermediate in this transformation. Notably, a commercial herbicide Oxadiazon could be successfully synthesized by this route.

KI-catalyzed reactions of aryl hydrazines with α-oxocarboxylic acids in the presence of CO2: access to 1,3,4-oxadiazol-2(3H)-ones

A novel KI-catalyzed synthesis of 1,3,4-oxadiazol-2(3H)-ones from aryl hydrazines, α-oxocarboxylic acids and CO₂ was reported.

Kinetic and experimental study on the reaction of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3.3.1]nonane in nitric acid

A comprehensive experimental and kinetic study on the reaction of DPT in nitric acid has been performed. The overall yield of the stepwise method for preparing HMX was up to 82.7%, which is a landmark breakthrough for the preparation of HMX from DPT.

A combined experimental and DFT mechanistic study for the unexpected nitrosolysis of N-hydroxymethyldialkylamines in fuming nitric acid

The reaction of dimorpholinomethane in fuming HNO3 was investigated. Interestingly, the major product was identified as N-nitrosomorpholine and a key intermediate N-hydroxymethylmorpholine was detected during the reaction by 1H-NMR tracking which indicates that the reaction proceeds via an unexpected nitrosolysis process. A plausible nitrosolysis mechanism for N-hydroxymethyldialkylamine in fuming nitric acid involving a HNO3 redox reaction is proposed, which is supported by both experimental results and density functional theory (DFT) calculations. The effects of ammonium nitrate and water on the nitrosolysis were studied using different ammonium salts as additives and varying water content, respectively. Observations show the key role of ammonium ions and a small amount of water in promoting the nitrosolysis reaction. Furthermore, DFT calculations reveal an essential point that ammonia, merged from the decomposition of the ammonium salts, acts as a Lewis base catalyst, and the hydroxymethyl group of the substrate participates in a hydrogen-bonding interaction with the NH3 and H2O molecules.

Mild dealkylative N-nitrosation of N,N-dialkylaniline derivatives for convenient preparation of photo-triggered and photo-calibrated NO donors

Direct N-nitrosation of N,N-dialkylanilines under mild, non-acidic and non-oxidative conditions.

Synthesis of 2-aminobenzophenones through acylation of anilines with α-oxocarboxylic acids assisted by tert-butyl nitrite

A highly facile all-in-one-pot synthesis of 2-aminobenzophenones directly from anilines, tert-butyl nitrite and α-oxocarboxylic acids under the catalysis of Pd(OAc)₂ is presented.

Synthesis ofN-sulfenyl-sulfoximines and -sulfenamides through a metal-free N–H/S–H dehydrocoupling reaction

A metal-free, iodine-catalyzed N–H/S–H dehydrocoupling reaction of sulfoximines and anilines with various thiols to construct sulfur–nitrogen bonds has been developed.

NH4I/tert-Butyl Hydroperoxide-Promoted Oxidative C–N Cleavage of Tertiary Amines Leading to Nitroaromatic Compounds

A NH4I/ tert-butyl hydroperoxide-promoted oxidation of tertiary N-aryl- N,N-dialkylamines in DMSO has been developed to access nitroaromatic compounds. This methodology involves sequential N-dealkylation reactions in one-pot and a radical pathway is proposed.

[3 + 2] cycloaddition and subsequent oxidative dehydrogenation between alkenes and diazo compounds: a simple and direct approach to pyrazoles using TBAI/TBHP

Herein, an efficient [3 + 2] cycloaddition and oxidative dehydrogenation reaction of diazo compounds and alkenes was well developed using TBAI/TBHP, leading to pyrazoles with moderate to high yields.

Transition-metal-free decarboxylation of dimethyl malonate: an efficient construction of α-amino acid esters using TBAI/TBHP

A transition-metal-free decarboxylation coupling process for the preparation of α-amino acid esters, which succeeded in merging hydrolysis/decarboxylation/nucleophilic substitution, is well described. This strategy uses commercially available inexpensive starting materials, catalysts and oxidants and has a wide substrate scope and operational simplicity.

Copper(ii)-catalyzed oxidative N-nitrosation of secondary and tertiary amines with nitromethane under an oxygen atmosphere

The combination of Cu(OTf)₂ and DBU under an O₂ atmosphere effectively promoted the N-nitrosation of both secondary aromatic/aliphatic amines and tertiary aromatic amines with nitromethane (CH₃NO₂).

Combination of fluoroalkylation and Kornblum–DeLaMare reaction: a new strategy for the construction of (Z)-β-perfluoroalkyl enaminones

A novel strategy has been developed for the highly chemo- and stereo-selective synthesis of (Z)-β-perfluoroalkyl enaminones via a multicomponent radical reaction involving sequential fluoroalkylation and Kornblum–DeLaMare reaction.

Palladium-catalyzed ortho-acyloxylation of N-nitrosoanilines via direct sp2 C–H bond activation

The palladium-catalyzed N-nitroso-directed ortho-acyloxylation of N-nitrosoanilines has been demonstrated via sp² C–H activation with PhI(OAc)₂ as the oxidant and Ac₂O/AcOH (1 : 1) or C₂H₅CO₂H as the reaction medium.

A general, simple and green process to access pyrrolo[2,1-a]isoquinolines using a KI/TBHP catalytic system

A novel KI/TBHP-catalyzed 1,3-dipolar cycloaddition/oxidation/aromatization cascade reaction provided a general, efficient and green access to biologically important pyrrolo[2,1-a]isoquinolines.

A powerful combination: recent achievements on using TBAI and TBHP as oxidation system

Recent achievements in the use of TBAI and TBHP as an oxidation system have been summarized and discussed.

Oxidative cleavage of benzylic C–N bonds under metal-free conditions

An interesting and practical metal-free strategy has been developed for the synthesis of aromatic aldehydes using various N,N-dimethylbenzylamines as starting materials.

TBAI-catalyzed oxidative synthesis of benzamides from acetophenones and carbinols

An interesting and convenient procedure for the oxidative transformation of acetophenones and carbinols to primary benzamides has been developed.