Methods for direct C(sp2)–H bonds azidation

Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations

The generation of azide radical (N₃˙) occurs from its precursors primarily via a single electron transfer (SET) process or homolytic cleavage by chemical methods or advanced photoredox/electrochemical methods. This in situ generated transient open-shell species has unique characteristic features that set its reactivity. In the past, the azide radical was widely used for various studies in radiation chemistry as a 1e^- oxidant of biologically important molecules, but now it is being exploited for synthetic applications based on its addition and intermolecular hydrogen atom transfer (HAT) abilities. Due to the significant role of nitrogen-containing molecules in synthesis, drug discovery, biological, and material sciences, the direct addition onto unsaturated bonds for the simultaneous construction of C-N bond with other (C-X) bonds are indeed worth highlighting. Moreover, the ability to generate O- or C-centered radicals by N₃˙ via electron transfer (ET) and intermolecular HAT processes is also well documented. The purpose of controlling the reactivity of this short-lived intermediate in organic transformations drives us to survey: (i) the history of azide radical and its structural properties (thermodynamic, spectroscopic, etc.), (ii) chemical reactivities and kinetics, (iii) methods to produce N₃˙ from various precursors, (iv) several significant azide radical-mediated transformations in the field of functionalization with unsaturated bonds, C-H functionalization via HAT, tandem, and multicomponent reaction with a critical analysis of underlying mechanistic approaches and outcomes, (v) concept of taming the reactivity of azide radicals for potential opportunities, in this review.

Direct halosulfonylation of alkynes: an overview

The difunctionalization reactions of easily available and inexpensive alkynes have emerged as a reliable, powerful, and step-economical approach for the construction of highly substituted complex alkenes in a one-pot manner, without the need for isolation of intermediates. A wide variety of transformations based on this concept have been successfully achieved for the preparation of synthetically and biologically important β-halovinyl sulfone scaffolds. In this Review, we summarize the recent advances and developments in this field and present a comprehensive overview of halosulfonylation of alkyne substrates with emphasis on the mechanistic features of the reactions.

Amphetamine Drug Detection with Inorganic MgO Nanotube Based on the DFT Calculations

In this study, the main challenge was to focus on the detection of amphetamine (AN) using a type of magnesium oxide nanotube (MgONT) sensor through density functional theory (DFT) calculations. Nowadays, due to the adverse effects of drug abuse, governments put all their efforts into detecting and managing illegal drugs such as AN. Therefore, the detection of AN in biological specimens is of great importance. In this study, through DFT calculations, the intrinsic sensing properties of MgONT were investigated for the detection of AN. We concluded that the MgONT considerably enhances the reactivity of the MgONT toward AN. Furthermore, the sensing response for the MgONT was 392.36. The results showed that there was a considerable change in the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and there was a drop in the band gap value (E_g). This decrease in the E_g value improved the electrical conductivity. Moreover, desorption of AN from the surface of the MgONT had a slight recovery time (~ 22.89 ms). This work illustrated that MgONT could be considered a proper candidate for electronic sensing and AN drug delivery in biological systems.

Progress and recent trends in the direct selenocyanation of (hetero)aromatic C-H bonds

This review covers recent advances in the direct selenocyanation of (hetero)aromatic C-H bonds with an emphasis on the reaction mechanisms. This novel approach is an effective means of preparing a variety of aromatic and heteroaromatic selenocyanates, which are extremely versatile synthetic precursors of selenium-containing compounds, such as selenols, seleninic acids, selenides, diselenides, and trifluoromethyl selenides.

Hydroxysulfonylation of alkenes: an update

The direct difunctionalization of inexpensive and widely available alkenes has been recognized as a strong and straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties in a single operation. This synthetic strategy avoids the purification and isolation of the intermediates and thus makes synthetic schemes shorter, simpler and cleaner. In this family of reactions, the hydroxysulfonylation of alkenes has emerged as an increasingly promising strategy for the synthesis of β-hydroxysulfones, which are found in many biologically important molecules and widespread applications in organic synthesis. The objective of this review is to illustrate the advancements in the field of hydroxysulfonylation of alkenes with special emphasis on the mechanistic details of the reaction pathways.

The direct difunctionalization of alkenes recognized as a straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties.

The adsorption of cathinone drug on the platinum decorated silicon carbide nanosheets: DFT studies

Cathinone (CTN), classified as stimulants, is one of the psychoactive drugs. Although the sale of CTN was controlled by international drug laws, it was still sold on the internet, and its overdose caused many deaths worldwide. As chemical sensors, two-dimensional (2D) nanomaterials have drawn attention to be used in various biological molecules. In the current study, the sensing characteristics of the intrinsic SiC monolayer (SiCM) and its Pt-decorated state (Pt@SiCM) were scrutinized toward the CTN drug by utilizing density functional theory (DFT) calculations. It was illustrated that the SiCM sensing response to CTN is insignificant (~ 10.6 at 298 K) due to the weak interaction with the adsorption energy of -0.25 eV. After the decoration of Pt on the SiCM, it was adsorbed above a hexagonal ring, which formed an η⁶-Pt half-sandwich and the adsorption energy was -3.62 eV. It was found that the Pt@SiCM strongly adsorbed CTN and the adsorption energy was -1.60 eV. Therefore, Pt-decoration augmented the SiCM sensing response to CTN from 10.3 to 716.6. The recovery time obtained for the CTN desorption from the Pt@SiCM surface was 12.7 s, which was short. It was concluded that Pt-decoration makes the SiCM a favorable candidate for CTN identification.

Regioselective C-H Azidation of Anilines and Application to Synthesis of Key Intermediate for Pharmaceutical

A catalytic system for regioselective C-H azidation of inactive anilines was developed. In the presence of CuSO₄·5H₂O, simultaneous addition of NaN₃ and Na₂S₂O₈ to aq. CH₃CN solution of free anilines under weakly acidic conditions (pH 4.5) smoothly underwent C-H azidation to provide corresponding α-azidated products in high yields. Methyl α-azidoanthranilate obtained by this method was readily transformed via simple reduction followed by cyclization to methyl 2-ethoxybenzimidazol-7-carboxylate, a key intermediate for antihypertensive Candesartan Cilexetil.

Vicinal halo-trifluoromethylation of alkenes

Both trifluoromethyl and halide groups are widely found in medicinally and pharmaceutically important compounds and, moreover, organohalides are commonly used as versatile intermediates in synthetic organic chemistry. Due to their prevalence and easy accessibility, alkene halo-trifluoromethylation provides a convenient way to install these valuable functionalities in complex targets. In this review, we summarize recent advances and achievements in this fast-growing research field. For clarity, the reactions were classified according to the type of halogen atom.

Recent trends in the direct oxyphosphorylation of C-C multiple bonds

Due to the wide importance of β-phosphorylated ketones as key building-blocks in the fabrication of various pharmaceutically active organophosphorus compounds, finding new and truly efficient methods for their preparation from simple, low-cost and ubiquitous feedstock materials within a single click is an interesting subject in organic synthesis. Recently, oxyfunctionalization of carbon-carbon multiple bonds has arisen as a straightforward and versatile tool for the synthesis of complex organic molecules from the simple and easily accessible alkenes/alkynes via a single operation. In this context, oxyphosphorylation of alkenes/alkynes with P(O)-H compounds has attracted considerable attention as a unique procedure for the construction of β-phosphorylated ketones. In this review, we outline the recent advances and developments in this fast-growing research field with particular emphasis on the mechanistic aspects of reaction.

Direct C-H bond halogenation and pseudohalogenation of hydrocarbons mediated by high-valent 3d metal-oxo species

Late-stage direct functionalization of the C-H bond is synthetically desirable. Metalloenzymes having metal-oxo active sites are well known to selectively catalyze hydroxylation and halogenation reactions with high efficiency. This review highlights the recent developments in the field of direct C-H halogenation and pseudohalogenation reactions catalyzed by the functional models of metalloenzymes.

Transition Metal Catalyzed Azidation Reactions

A wide range of methodologies for the preparation of organic azides has been reported in the literature for many decades, due to their interest as building blocks for different transformations and their applications in biology as well as in materials science. More recently, with the spread of the use of transition metal-catalyzed reactions, new perspectives have also materialized in azidation processes, especially concerning the azidation of C–H bonds and direct difunctionalization of multiple carbon-carbon bonds. In this review, special emphasis will be placed on reactions involving substrates bearing a leaving group, hydroazidation reactions and azidation reactions that proceed with the formation of more than one bond. Further reactions for the preparation of allyl and vinyl azides as well as for azidations involving the opening of a ring complete the classification of the material.

Cross-dehydrogenative Coupling Reactions Between Formamidic C(sp2)-H and X-H (X = C, O, N) Bonds

In the last decade, the scientific community has witnessed explosive growth in research on the direct carbamoylation of C-H and X-H (X = N, O) bonds with formamides via cross-dehydrogenative coupling reactions. This novel approach is an effective means of preparing a variety of carboxamide, carbamate as well as urea derivatives, which are prevalent in medicinal chemistry and natural product synthesis. This review elaborates the most important advances and developments in the field, with an emphasis on the reaction patterns and mechanisms.

Dirhodium(II)-Catalyzed C(sp2 )-H Azidation of Benzaldehydes

Multiple steps are needed to achieve the C-H functional of aromatic aldehyde, since the C-H functional reaction usually occurs preferentially at the aldehydic C-H bond over the aryl C-H bond. We report an efficient azidation method mediated by dirhodium(II) catalysts to achieve the direct aryl azidation of aromatic aldehydes avoiding the simultaneous use of protected aldehydes and prefunctionalized arenes. The regioselectivity of this method is similar to those of typical aromatic electrophilic substitution reactions. The resulting azidobenzaldehyde products are versatile building blocks or precursors for the synthesis of many biologically active compounds. The mechanism studies indicate that the one-electron oxidative intermediate Rh₂ ^(II,III) N₃ is responsible for the azide transfer.

Tandem transformations and multicomponent reactions utilizing alcohols following dehydrogenation strategy

In this review, the progress of tandem transformation of nitro, nitrile and azide functionalities is summarised to develop new C–C and C–N bonds as well as multi-component reactions using alcohols.

N-Fluorobenzenesulfonimide: a useful and versatile reagent for the direct fluorination and amination of (hetero)aromatic C–H bonds

This review updates recent advances and developments in the direct fluorination and amination of (hetero)aromatic C–H bonds utilizing N-fluorobenzenesulfonimide, classified according to the type of catalyst.

This review updates recent advances and developments in the direct fluorination and amination of (hetero)aromatic C–H bonds utilizing N-fluorobenzenesulfonimide, classified according to the type of catalyst.