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An efficient and practical method for the bromination of electron-rich arenes and heteroarenes was developed by using S -methyl methanethiosulfonate as the oxidant. All the bromine atoms were basically transferred to the brominated products, demonstrating the exceptional atom economy and practicality of the proposed protocol. The method reduces the amount of bromine required for this reaction system and obtains products in moderate to good yields. [ABSTRACT FROM AUTHOR]

We report a catalytic late‐stage bromination strategy for the α‐C−H functionalization of aryl acetic acid. The aryl acetic acid was transformed into enediolate in the presence of an (AcO)4B2O with the combination of DBU, and consequently underwent an electrophilic bromination reaction with pyridinium tribromide. A wide range of α‐bromo aryl acetic acids were isolated in yields of 19–65 %. In addition, the reaction could be performed on a gram scale, and several transformations of the products were carried out. [ABSTRACT FROM AUTHOR]

A series of new small-molecule acceptors—NA9, NA10, and NA11—based on benzo[b]phenazine are synthesized. The chlorinated NA10 and brominated NA11 exhibit improved molecular packing and enhanced charge transport, resulting in higher power conversion efficiencies (PCEs) of 15.65% and 16.64%, respectively, compared to 11.66% for the non-halogenated NA9. These results underscore the great potential of peripheral halogenation particularly bromination, in achieving high-performance OSCs. [ABSTRACT FROM AUTHOR]

Most molecular catalysts have been developed employing polar functional groups as catalytic sites. However, the use of non‐polar functional groups for catalysis has received less attention due to their modest molecular interactions while the bioorthogonal reactivity of non‐polar alkenes as substrates is frequently used in click chemistry. In this study, we conducted mechanistic studies on the catalysis of trans‐cyclooctene (TCO) derivatives with the strained olefin as the catalytic site using kinetic and computational analyses to aid the design of more active olefin catalysts. The analysis reveals the significant role of the benzyl substituents in accelerating the generation of bromonium species through dispersion interaction in the rate‐determining step. Guided by the mechanistic insights, we developed bifunctional TCO catalysts bearing a functionalized benzyl group, taking advantage of the remarkable substituent effects. Experimental studies confirmed the theoretical model and revealed that TCO with a para‐hydroxybenzyl group provided excellent catalytic activity. Furthermore, inclusion of the functionalized benzyl groups allowed more readily available and robust cis‐cyclooctenes to be used as active catalysts, expanding the practical utility of the olefin catalysts. By using a photochemically labile masking group on the para‐hydroxybenzyl substituent, the first light‐gated bromination catalyst was developed, enabling spatiotemporal control of the transformation. [ABSTRACT FROM AUTHOR]

Erastin, a classic ferroptosis inducer, mediates ferroptosis through various molecular pathways. A highly efficient and convenient synthesis of erastin has been developed, starting from 2-nitrobenzoic acid through 7 steps in an overall yield of 21.6%. This synthesis approach features the efficient construction of the key quinazolinone core and highly selective bromination. [ABSTRACT FROM AUTHOR]

The [Fe]/H2O2 oxidation system has found wide applications in chemistry and biology. Halogenation with this [Fe]/H2O2 oxidation protocol and halide (X-) in the biological system is well established with the identification of heme-iron-dependent haloperoxidases. However, mimicking such halogenation process is rarely explored for practical use in organic synthesis. Here, we report the development of a nonheme iron catalyst that mimics the heme-iron-dependent haloperoxidases to catalyze the generation of HOBr from H2O2/Br- with high efficiency. We discovered that a tridentate terpyridine (TPY) ligand designed for Fenton chemistry was optimal for FeBr3 to form a stable nonheme iron catalyst [Fe(TPY)Br3], which catalyzed arene bromination, Hunsdiecker-type decarboxylative bromination, bromolactonization, and oxidation of sulfides and thiols. Mechanistic studies revealed that Fenton chemistry ([Fe]/H2O2) might operate to generate hydroxyl radical (HO), which oxidize bromide ion [Br-] into reactive HOBr. This nonheme iron catalyst represents a biomimetic model for heme-iron-dependent haloperoxidases with potential applications in organic synthesis, drug discovery, and biology. [ABSTRACT FROM AUTHOR]

A general protocol for the synthesis of 3,4-dihalogen substituted 1,8-naphthalimides is proposed, starting from available and cheap 1,8-naphthalic anhydride. The reported new compounds have only bromine or chlorine atoms as substituents, in contrast to the known iodo-containing analogues. This is an advantage in possible aryl nucleophilic substitution or cross-coupling modifications, making them interesting and important building-block molecules in naphthalimide chemistry. Although the procedure includes five synthetic steps, they are quick and straightforward. The overall yields are relatively high (48–62%), and only one column of chromatographic purification is needed. All the reactions were carried out on a multigram scale to allow the target building-block compounds to be obtained in sufficient amounts for further derivatizations. [ABSTRACT FROM AUTHOR]

This communication reports a reliable one-pot synthetic protocol for preparation on a multigram scale of 3-bromo- and 3,4-dibromo-6-nitro-1,8-naphthalic anhydride from commercially available and economical 1,8-naphthalic anhydride. The synthetic steps used were nitration and selective bromination in sulfuric acid at room temperature. The reaction takes place under mild conditions and is completely controllable depending on the equivalents of the brominating reagent used. Both anhydrides are powerful building blocks in naphthalimide chemistry. In addition, their imides and esters were also synthesized. [ABSTRACT FROM AUTHOR]

Bromination by N-bromosuccinimide of the β-carboline alkaloid 8-acetylharmine in CH2Cl2 smoothly formed 8-acetyl-6-bromoharmine. Cross coupling of 8-acetyl-6-bromoharmine with arylboronic acids in aqueous toluene in the presence of Pd(PPh3)4 as a catalyst, Na2CO3 as a base, and ammonium salt Bu4N+Br- as an additive synthesized the corresponding 6-aryl-8-acetylharmine derivatives. The new aryl-substituted 8-acetylharmine derivatives possessed moderate cytotoxicity and antidepressant activity in the Porsolt test. [ABSTRACT FROM AUTHOR]

The combination of HBr, TMSO (tetramethylene sulfoxide) and HFIP (hexafluoroisopropanol) has been utilized in the modification of pyrrolo[2,1‐a]isoquinoline derivatives through bromination, dimerization and sulfenylation respectively. In these processes, HBr serves as the source of bromine and TMSO acts as an oxidant. HFIP also plays an essential role for the oxidative dimerization. Chemoselectivity can be easily controlled by adjusting the parameters such as reaction time, ratio of reagents and the addition of nucleophile. [ABSTRACT FROM AUTHOR]

We report an in-depth study of the reductive activation of O2 by the nonheme [FeII(L 25)(MeCN)]2+ complex carried out by cyclic voltammetry. Experimental evidence is obtained for the slow coordination of dioxygen to the ferrous center yielding an FeII/O2 adduct with a strong FeII–O2 character rather than an FeIII–superoxo one. Electron injection in the FeII–O2 species occurs at a potential of ca. −700 mV vs. SCE, i.e. 200 mV above the O2 to O2˙− reduction, leading to the formation of a FeIII–peroxo intermediate and then FeIII–hydroperoxo upon protonation by residual water. The experimental CVs recorded at variable scan rate or variable FeII concentration are well simulated taking into account a detailed mechanism initiated by the competitive reduction of O2 and the FeII–O2 adduct. Analysis of the concentration of the reaction intermediates generated as a function of the applied potential indicates that the FeIII–peroxo intermediate significantly accumulates at a potential of −650 mV. Oxidative bromination of anisole is assayed under electrolytic conditions at this potential to yield bromoanisole products. The low faradaic yields observed reveal that deleterious reactions such as direct reduction of reaction intermediates likely occur. Based on the detailed mechanism elucidated, a number of improvements to achieve more efficient catalytic reactions can be proposed. [ABSTRACT FROM AUTHOR]

Investigations of bromination of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione revealed that the reaction proceeded most efficiently with N-bromosuccinimide in sulfuric acid and depending on the reaction conditions, can give mono-, di-, tri- and tetrabromo derivatives of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione. A series of the major isomers was isolated, and their structure was proven using heteronuclear multiple bond correlation NMR spectroscopy and high-resolution mass spectrometry. [ABSTRACT FROM AUTHOR]

m‐Pyripentaphyrins(1.0.0.0.0) were synthesized by Suzuki‐Miyaura coupling of 3,5‐bis(5‐borylpyrrol‐2‐yl)‐BODIPY with 2,6‐dibromopyridine. Upon treatment with PhBCl2, pyripentaphyrin 1 provided mono‐ and bis‐BIII complexes sequentially. The Mono‐BIII complex shows a distorted tetrahedral coordinated BIII with a σ‐phenyl ligand on the BIII and the bis‐BIII complex shows an additional distorted tetrahedral coordinated BIII with a B−H bond. Bromination of the pyripentaphyrins with N‐bromosuccinimide (NBS) resulted in regioselective formation of 8‐bromopyripentaphyrins, which were dimerized to 8,8'‐linked dimers by reductive coupling with Ni(cod)2. While all these pyripentaphyrins are nonaromatic, they exhibit characteristic broad absorption bands at long wavelength near the NIR region, indicating the presence of effective macrocyclic conjugation. [ABSTRACT FROM AUTHOR]

An iron-mediated bromination/cyclization for the synthesis of bromobenzoxazines from olefinic amides has been successfully developed. In this protocol, the simple iron salt FeBr3 was employed as a bromination reagent, giving the bromobenzoxazine products in moderate to excellent yields. This methodology features good functional group tolerance, gram-scale synthesis, and green reaction conditions by the use of air as the terminal oxidant. Preliminary mechanistic studies suggest that a free radical pathway is involved. [ABSTRACT FROM AUTHOR]

Achieving electronic/steric control and realizing selectivity regulation in nanocatalysis remains a formidable challenge, as the dynamic nature of metal‐ligand interfaces, including dissolution (metal leaching) and structural reconstruction, poses significant obstacles. Herein, we disclose carboranyls (CBs) as unprecedented carbon‐bonded functional ligands (Eads.CB‐Au(111)=−2.90 eV) for gold nanoparticles (AuNPs), showcasing their exceptional stabilization capability that is attributed by strong Au−C bonds combined with B−H⋅⋅⋅Au interactions. The synthesized CB@AuNPs exhibit core(Aun)‐satellite(CB2Au−) structure, showing high stability towards multiple stimuli (110 °C, pH=1–12, thiol etchants). In addition, different from conventional AuNP catalysts such as triphenylphosphine (PPh3) stabilized AuNPs, dissolution of catalytically active gold species was suppressed in CB@AuNPs under the reaction conditions. Leveraging these distinct features, CB@AuNPs realized outstanding p : o selectivities in aromatic bromination. Unbiased arenes including chlorobenzene (up to >30 : 1), bromobenzene (15 : 1) and phenyl acrylate were examined using CB@AuNPs as catalysts to afford highly‐selective p‐products. Both carboranyl ligands and carboranyl derived counterions are crucial for such regioselective transformation. This work has provided valuable insights for AuNPs in realizing diverse regioselective transformations. [ABSTRACT FROM AUTHOR]

Halogenation is one of the most important transformations in organic synthesis. Halogenated compounds are employed in many reactions to prepare useful molecules. Many methods have been developed to introduce halogens into different compounds. Visible light‐mediated reactions are the efficient, low‐toxic, and mild‐condition methods applied for various organic chemistry transformations. Remarkably, there has been an increasing development in the application of visible light‐induced halogenation in recent years. Herein, we present a comprehensive summary of halogenation reactions including chlorination, bromination, and iodination under visible light irradiation since 2020. [ABSTRACT FROM AUTHOR]

The influence of the 7-O-acetyl group of acetylhaplophyllidine (2) on the bromination process was studied. Acetylhaplophyllidine in bromination by molecular Br2 and N-bromosuccinimide under various conditions formed multicomponent mixtures consisting of bromination products of intramolecular annelation (3, 4, and 6) and bromo-derivatives of 4-oxofuranoquinolines (5 and 7). [ABSTRACT FROM AUTHOR]

Bromination of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical with bromine or N-bromo-succinimide (NBS) affords a complex mixture of bromo- and nitro-derivatives of the starting material. In this study, by chromatographic separation, most of the reaction products were isolated. Suitable crystals for X-ray measurements were obtained and characterized for the compounds 2-p-bromophenyl-2-phenyl-1-picrylhydrazyl free radical (Br-DPPH), 2-p-bromophenyl-2-phenyl-1-picrylhydrazine (Br-DPPH-H), and 2,2-(p-bromophenyl)-1-(2-bromo-4,6-dinitrophenyl)hydrazine (Br2-DPPBr-H). [ABSTRACT FROM AUTHOR]

An unexpected and selective synthetic technique was devised for 3-bromo-2-arylimidazo[1,2-a]pyridine and 3-formyl-2-arylimidazo[1,2-a]pyridine derivatives synthesis, utilizing DMSO and copper(II) bromide under time-controlled settings. Initially, the imidazopyridines underwent bromination, followed by the subsequent conversion of the brominated imidazopyridines into formylated imidazopyridines. This innovative technique has various advantages over previous ones, such as sequential synthesis of brominated and formylated imidazo[1,2-a]pyridines and, for the first time, utilizing CuBr2 and DMSO as dual active agents simultaneously. This practical process can moreover produce two widely used products in the medical and pharmaceutical realm which increases its efficiency and adaptability. [ABSTRACT FROM AUTHOR]

We have previously demonstrated that an appropriately substituted four-membered-ring 1,2-diazacyclobutene is a useful compound in organic synthesis for the introduction of strained 1,2-diazetidine rings. In order to further explore the reactivity of this interesting heterocycle, we sought a method to improve upon the poor synthetic yield reported earlier. A novel route involving the synthesis of a similarly substituted 1,2-diazetidine compound followed by free-radical bromination and base-catalyzed debromination appeared promising. While there are some studies on the synthesis of the desired 1,2-diazetidine precursor, when we attempted its synthesis, we instead observed the exclusive formation of an eight-membered "dimer"-like compound. The structure of this compound was confirmed via single-crystal X-ray analysis. Fortunately, an alternative synthetic approach for the formation of the desired 1,2-diazetidine precursor proved successful, and the structure of the precursor has been confirmed via X-ray analysis. However, unfortunately, the required bromination step proved to be more challenging than expected, and ultimately, this route had to be abandoned since the anticipated improvement upon the original yield did not seem promising. Single-crystal X-ray analysis proved pivotal in properly identifying the structures of the synthesized compounds. [ABSTRACT FROM AUTHOR]

Herein, we disclose a new strategy that rapidly and reliably incorporates bromine atoms at distal, secondary C(sp3)−H sites in aliphatic amines with an excellent and predictable site‐selectivity pattern. The resulting halogenated building blocks serve as versatile linchpins to enable a series of carbon‐carbon and carbon‐heteroatom bond‐formations at remote C(sp3) sites, thus offering a new modular and unified platform that expediates the access to advanced sp3 architectures possessing valuable nitrogen‐containing saturated heterocycles of interest in medicinal chemistry settings. [ABSTRACT FROM AUTHOR]

The bromination of benzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole) was studied. An efficient method has been developed for the synthesis of 4,5-dibromobenzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole), an important intermediate for the preparation of highly efficient photochromic diarylethenes for photosensitive and mechanoreactive materials that can be useful in a number of applications, including stress perception and information storage. [ABSTRACT FROM AUTHOR]

The bromination of eugenol using molecular bromine (Br2) has been widely reported. However, the outcomes have been inconsistent, and as a result, the specific steps of the bromination process have not been definitively established. This research aims to synthesize various derivatives of bromo eugenol, incorporating bromine atoms either in the alkene group, the aromatic ring, or both. The synthetic approaches employed include: (1) direct bromination of eugenol using 1.2, 2.4, and 3.6 equivalents (equiv) of Br2 in chloroform, (2) bromination of eugenyl benzoate with 2.4 equiv of Br2 in chloroform, and (3) debromination of the 1,2-dibromide functionality in selected bromination products using an excess of zinc in ethanol. The bromination steps of eugenol were then proposed based on the composition of the products obtained. Alkene bromination of eugenol predominated with 1.2 equiv of Br2, followed by aromatic bromination with excess Br2 (2.4 and 3.6 equiv). Aromatic substitution primarily occurred at position 6 (ortho to the hydroxyl group) and subsequently at position 5 (para to the methoxy group). Based on these results, we propose that the bromination of eugenol with Br2 proceeds initially through electrophilic addition to the alkene group, followed by electrophilic substitution on the aromatic ring. Protection of the phenol as a benzoyl ester shifted the regioselectivity of the first aromatic bromination from position 6 to 5. Furthermore, the 1,2-dibromide group has been successfully removed by zinc, resulting in derivatives containing bromine atoms only at the aromatic ring. This is by far the first comprehensive report on the bromination of eugenol with Br2 and the first one reporting the bromination of alkene as the main route of bromination with a nearly equimolar amount of Br2.

Both aryl and benzyl polybromides have gained significant importance as reactive building blocks in polymer and materials chemistry. Their preparation primarily relies on established synthetic methods using molecular bromine or N-bromosuccinimide, known for their reliability and effectiveness. However, from a sustainability perspective, these methods suffer from the generation of stoichiometric amounts of byproducts and often encounter selectivity troubles. To mitigate these issues, we extended the greener peroxide-bromide halogenation method, initially developed for monobromides, to afford aryl-cored polybromides in high yields. The same method can be employed in two variants modulated by light irradiation. This external switch can be used to selectively trigger side-chain or core halogenation.

There are many indole alkaloids that contain diverse functional groups attached to the benzene ring on the indole core. Promising biological activities of these alkaloids have been reported. Herein, we report the indole C5‐selective bromination of indolo[2,3‐a]quinolizidine alkaloids by adding nearly equimolar amounts of Br3 ⋅ PyH and HCl in MeOH. The resulting reaction plausibly proceeds through an indoline intermediate by the nucleophilic addition of MeOH to the C3‐brominated indolenine intermediate. Data support the intermediacy of a C3‐, C5‐dibrominated indolenine intermediate as a brominating agent. These conditions demonstrate excellent selectivity for indole C5 bromination of natural products and their derivatives. Thus, these simple, mild, and metal‐free conditions allow for selective, late‐stage bromination followed by further chemical modifications. The utility of the brominated product prepared from naturally occurring yohimbine was demonstrated through various derivatizations, including a bioinspired heterodimerization reaction. [ABSTRACT FROM AUTHOR]

7-Bromo-4-chloro-1H-indazol-3-amine is a heterocyclic fragment used in the synthesis of Lenacapavir, a potent capsid inhibitor for the treatment of HIV-1 infections. In this manuscript, we describe a new approach to synthesizing 7-bromo-4-chloro-1H-indazol-3-amine from inexpensive 2,6-dichlorobenzonitrile. This synthetic method utilizes a two-step sequence including regioselective bromination and heterocycle formation with hydrazine to give the desired product in an overall isolated yield of 38–45%. The new protocol has been successfully demonstrated on hundred-gram scales without the need for column chromatography purification. This new synthesis provides a potential economical route to the large-scale production of this heterocyclic fragment of Lenacapavir. [ABSTRACT FROM AUTHOR]

Based on the strong coordination ability of substituted imines towards transition metals of different oxidation states, the coordination of the HL imine ligand with the Cu2+ ion to form the Cu–bis–imine complex was achieved in 2:1 molar ratios. Their structures were confirmed with various spectroscopic tools. Heterogeneously, CuL2 was successfully appended on ZnO@TiO2 nanoparticles, as the less harmful materials, within the deprotonated p‐hydroxy chain of the bonded ligand in CuL2. The surface and internal structural morphologies of ZnO@TiO2@CuL2 were analyzed using X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), high‐resolution transmission electron microscopy (HRTEM), energy‐dispersive X‐ray spectroscopy (EDS), and infrared (IR) spectroscopy, in addition to thermogravimetric analysis (TGA). The catalytic behavior of both catalysts, CuL2 (the homogeneous catalyst) and ZnO@TiO2@CuL2 (the heterogeneous catalyst), was examined in the benzyl alcohol redox protocols using H2O2 for their optimization. α,β‐Cinnamic acid decarboxylative bromination in the presence of potassium bromide and H2O2 in water was studied with both catalysts, in which (2‐bromovinyl)benzene was the chemoselective product. Both Cu catalysts displayed appreciable catalytic effectiveness for the oxidation protocols and the decarboxylative bromination reactions. CuL2 recorded less required time for optimization than that of the heterogeneous catalyst. The catalytic effectiveness of CuL2 was less promoted than that of ZnO@TiO2@CuL2. Despite the less performance in yield of benzaldehyde for the oxidation protocols with ZnO@TiO2@CuL2, ZnO@TiO2@CuL2 had more recycling than its homogeneous counterpart, with seven to three times, respectively. [ABSTRACT FROM AUTHOR]

Context: This study delves into hole-electron transport and distribution properties inherent in mono-brominated dibenzofuran (DBF) and dibenzothiophene (DBT) isomers. As determined by frontier molecular orbitals, all brominated structures have narrower bandgaps than their primary structures. The TD-DFT calculation showed that 2BDBT had the highest absorption wavelength of all molecules at 315.35 nm. Notably, the study unveils remarkably low electron and hole reorganization energies due to bromine substitution in DBF and DBT molecules. Specifically, the 4BDBF has the lowest hole reorganization energy of all DBF configurations, 0.229 eV. In addition, 3BDBF has 0.226 eV less electron reorganization energy than all other molecules. Compared to DBT, 3BDBT has the lowest electron reorganization energy of 0.254 eV. Overall, this research sheds significant light on the fundamental electronic and hole transport characteristics of bromine-substituted DBF and DBT isomers, highlighting their promising role in polymer design as donors/acceptors for advanced organic electronic applications. Methods: Molecular structures were optimized using Density Functional Theory (DFT) B3LYP/6-311 + + G (d, p) level of theory, and the study further elucidates these molecules' energy levels and absorption spectra through Time-Dependent Density Functional Theory TD-DFT; these calculations were performed using Gaussian 09W software package. The key parameters such as reorganization energies, Electron Localization Function map, Laplacian Bond Order, and NCI-RDG were meticulously examined for the molecules with the results of DFT calculations were analyzed and displayed by utilizing the software packages VMD 1.9.4 and Multiwfn 3.8, aiming to comprehend their charge transport and distribution properties. [ABSTRACT FROM AUTHOR]

The bromination of eugenol using molecular bromine (Br2 ) has been widely reported. However, the outcomes have been inconsistent, and as a result, the specific steps of the bromination process have not been definitively established. This research aims to synthesize various derivatives of bromo eugenol, incorporating bromine atoms either in the alkene group, the aromatic ring, or both. The synthetic approaches employed include (1) direct bromination of eugenol using 1.2, 2.4, and 3.6 equivalents (equiv) of Br2 in chloroform, (2) bromination of eugenyl benzoate with 2.4 equiv of Br2 in chloroform, and (3) debromination of the 1,2-dibromide functionality in selected bromination products using an excess of zinc in ethanol. The bromination steps of eugenol were then proposed based on the composition of the products obtained. Alkene bromination of eugenol predominated with 1.2 equiv of Br2, followed by aromatic bromination with excess Br2 (2.4 and 3.6 equiv). Aromatic substitution primarily occurred at position 6 (ortho to the hydroxyl group) and subsequently at position 5 (para to the methoxy group). Based on these results, we propose that the bromination of eugenol with Br2 proceeds initially through electrophilic addition to the alkene group, followed by electrophilic substitution on the aromatic ring. Protection of the phenol as a benzoyl ester shifted the regioselectivity of the first aromatic bromination from position 6 to 5. Furthermore, the 1,2-dibromide group has been successfully removed by zinc, resulting in derivatives containing bromine atoms only at the aromatic ring. This is by far the first comprehensive report on the bromination of eugenol with Br2 and the first one reporting the bromination of alkene as the main route of bromination with a nearly equimolar amount of Br2 . [ABSTRACT FROM AUTHOR]

The total synthesis of alternatamines B and D is outlined. Alternatamine B demonstrates moderate antibacterial activity across a broad spectrum of bacteria. Both alternatamines B and D feature an intriguing 5,6‐dibromoindole skeleton, derived from a four‐step sequence starting with 3,4‐dibromoaniline and achieving a total yield of 48 %. The key steps involve: (a) functional group modifications, including iodination, of 3,4‐dibromoaniline with two bromine substituents to obtain the Sonogashira precursor; (b) indole synthesis through Sonogashira coupling and 5‐endo‐dig cyclization; (c) carbon chain extension and introduction of the nitrogen atom at the C3 of the indole. Subsequently, the tryptamine analogue was coupled with an L‐leucine derivative through amide bond formation after deprotection, yielding alternatamide D. The first total synthesis of alternatamine B was also achieved by selectively introducing a bromine substituent at the C2 of the indole, employing optimal bromination conditions. [ABSTRACT FROM AUTHOR]

A range of densely functionalized ullazines have been synthesized by a one‐pot Rh(III)‐catalyzed twofold C−H activation/oxidative annulation of N‐arylpyrroles with alkynes. Electrophilic bromination at 5‐ or 5,7‐ positions of the EWG‐substituted ullazine core offers an interesting single or double entry for further extended functionalization. Mechanistic considerations suggest two complementary paths, EWG‐assisted and SEAr, for the C−H activations. All ullazines exhibit strong fluorescence emissions. Ullazines bearing thiophene and triarylamine units at 5‐ and 5,7‐ positions show a significant bathochromic shift in their emission spectra, attributed to the more extended electronic circuits present. [ABSTRACT FROM AUTHOR]

We report, an intramolecular ipso‐halocyclization of N‐arylpropynamides using readily available hypervalent iodine reagent as mild oxidant and alkali halides like KCl, KBr, and KI as the halogen source. Using this method, a broad range of valuable halogenated spiro[4.5]trienones can be obtained in an excellent yield at room temperature. Notably, this protocol doesn't require para‐substituents such as methoxy or fluoro group on the N‐aryl ring. Also, this reaction takes place in the absence of any metal catalyst under aqueous conditions and exhibits a broad substrate scope with high functional group tolerance. A plausible reaction mechanism is proposed based on control experiments. [ABSTRACT FROM AUTHOR]

Synthesis of trans‐dioxidomolybdenum(VI)‐meso‐tetraphenylporphyrin (trans‐[MoVIO2(TPP)], 1) and trans‐dioxidomolybdenum(VI)‐meso‐tetra(p‐chlorophenyl)porphyrin (trans‐[MoVIO2(TCPP)], 2) by reacting the corresponding free‐base porphyrins with Mo(CO)6 in 1,2,4‐trichlorobenzene at 190 °C has been reported. These are the second examples in the literature where molybdenum‐porphyrins have trans‐[MoVIO2] group, identified by single crystal X‐ray study. Both complexes have been utilized as functional model of haloperoxidases for the oxidative bromination of various phenol derivatives using KBr, H2O2 and HClO4 as green brominating reagents in aqueous medium. These complexes displayed very high TOF values (up to 16.2 s−1 for catalyst 2) representing excellent catalytic activity. To the best of our knowledge, this is the first report presenting trans‐dioxidomolybdenum(VI) based porphyrin as haloperoxidases mimicking oxidative bromination of various phenol derivatives. [ABSTRACT FROM AUTHOR]

This article provides an overview of photoredox-catalyzed C(sp2)–H bond functionalization reactions, which use low-energy photons to enable reactions under mild conditions. It discusses the contributions of researchers in advancing the field and explores the potential of using organic photocatalysts. The article focuses on the author's group's work in utilizing these reactions for C–H bond functionalizations, specifically in the context of enamides. The researchers explored various reactions, including the functionalization of enamide β-C(sp2)-H bonds, phosphorylation of alkenyl C(sp2)-H bonds, and bromination and alkylation of (hetero)arene C(sp2)-H bonds. These reactions have applications in the synthesis of natural products and pharmaceuticals, and further research is needed to develop new transformations and expand their applications. [Extracted from the article]

Three congenetic Cd-MOFs with different pores were successfully synthesized via solvent-regulated strategy, and they were used as friction materials to regulate the TENG output, which could drive electrolysis systems to promote the direct bromination of aromatic compounds in high yields with good regioselectivity. [Display omitted] Optimizing friction materials based on molecular diversity in a molecular framework system is an effective method to improve the output performance of triboelectric nanogenerators (TENGs). In this study, three cadmium(II) metal–organic frameworks (Cd-MOFs) with different cavities were synthesized solvothermally by the assembly of cadmium nitrate (Cd(NO 3) 2 ·4H 2 O), 4′,4′''-carbonylbis(([1,1′-biphenyl]-3,5-dicarboxylic acid)) (H 4 CBBD), and trans -1,2-bis(4-pyridyl)ethylene (4,4′-bpe) via a solvent-regulated strategy. The topology and porosity of Cd-MOFs could be controlled effectively by the solvent constituents and were demonstrated to be closely related to their triboelectric behaviors. Theoretical calculations and experimental characterizations revealed that the TENGs fabricated by the Cd-MOF with maximum porosity exhibited the best triboelectric performance owing to the enhanced specific surface area and surface potential. In the applications, the high-output TENGs can be successfully used as an efficient power supply for electrochemical systems, enabling the direct bromination of aromatic compounds in high yields with good regioselectivity. This study provides a simple and feasible method to optimize positive friction materials at the molecular level and develops the practical applications of TENGs in electrochemical systems. [ABSTRACT FROM AUTHOR]

Brominated activated carbon (AC/Br2) powder was used as a filler in poly(vinyl chloride) (PVC) to prepare PVC‐based composite films by hot pressing. The AC/Br2 filler was obtained by liquid phase bromination and contained both oxygen and bromine. In comparison with the unmodified AC, the AC/Br2 was subjected to thermogravimetric analysis in air and argon and temperature‐programmed desorption mass spectrometry in vacuum, which identified carbon‐oxygen and bromine groups and showed the comparable thermal stability of AC/Br2 and AC. XPS shows the predominance of phenolic groups among the carbon‐oxygen groups. Scanning electron microscopy and transmission electron microscopy showed preserved morphology and microstructure, while N2 adsorption showed a microporosity decrease after bromination. FTIR analysis suggested non‐chemical interactions between PVC and AC/Br2. As the AC/Br2 content in the PVC‐based composite films increases from 0.2 to 30 wt %, the electromagnetic radiation (EMR) reflection at Ka‐band microwave frequencies increases. To reduce the EMR reflection, the proposed composite films should contain a maximum of 0.2 wt % AC/Br2. The results indicate that the microwave properties of PVC‐based composite films can be tuned by adjusting the AC/Br2 content. [ABSTRACT FROM AUTHOR]

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A selective C(sp3)−S bond cleavage of thioethers mediated by NBS is developed. Various alkyl bromides have been obtained in good yields using N‐aryl‐3‐(methylthio)propanamides and arylmethylene alkylthioethers. Mechanistic studies suggest that the formation of 3‐bromo‐N‐arylpropanamides may involve sulfoxide intermediates, while the arylmethylene bromides are formed through direct bromination process mediated by NBS. The significance of this strategy lies in its pioneering use of NBS for C−S bond cleavage and subsequent bromination reaction. [ABSTRACT FROM AUTHOR]

A nitrosonium catalyzed bromination of electron‐rich arenes has been developed, using bromide salts as bromine sources, oxygen gas as a terminal oxidant and Brønsted acids (sulfuric acid, TFA or HBr). This arene bromination process is free of transition metals, proceeding in acetic acid and under mild temperatures (25–50 °C) to give brominated arenes with good to excellent yields. Our mechanistic studies indicated that this oxidative bromination of arenes reaction is catalyzed by nitrosnium ion (NO+), without the involvement of Br2 or Br+. The kinetic isotope effect of this reaction was measured using pentadeuteriophenyl phenyl ether (kH/kD=1.1). [ABSTRACT FROM AUTHOR]

2,6-Di-tert-butyl-4-methylphenol reacted with an equimolar amount of benzyltrimethylammonium tribromide to give 4-bromomethyl derivative but not 4-hydroxymethyl derivative as was reported earlier. The present work is devoted to the synthesis of 4-bromomethylphenols with bulky tert-butyl and/or isobornyl moieties at positions 2 and 6. [ABSTRACT FROM AUTHOR]

Silica nanoparticles synthesized solely from organosilanes naturally possess a greater number of organic functionalities than silica nanoparticles surface-modified with organosilanes. We report the synthesis of organically modified silica (ORMOSIL) nanoparticles with a mesoporous and surface-rough morphology and with a high surface area, made solely from vinyltrimethoxy silane. We chemically modified these vinyl silica nanoparticles using bromination and hydroboration, and demonstrated the high accessibility and reactivity of the vinyl groups with an ~85% conversion of the functional groups for the bromination of both particle types, a ~60% conversion of the functional groups for the hydroboration of surface-rough particles and a 90% conversion of the functional groups for the hydroboration of mesoporous particles. We determined that the mesoporous vinyl silica nanoparticles, while having a surface area that lies between the non-porous and surface-rough vinyl silica nanoparticles, provide the greatest accessibility to the vinyl groups for boronation and allow for the incorporating of up to 3.1 × 106 B atoms per particle, making the resulting materials attractive for boron neutron capture therapy. [ABSTRACT FROM AUTHOR]

The electrochemical bromination of enamide derivatives was developed using inexpensive and non-toxic sodium bromide (NaBr). This transformation enabled the direct stereoselective formation of a C(sp2)−Br bond and was applied to a wide variety of enamides without the need for external hazardous oxidants, reductants or metal catalysts. The protocol showed a general efficiency and tolerance, allowing access to brominated enamides with yields ranging from 56% to 85%. The reaction conditions were applied to the chlorination reaction using sodium chloride (NaCl). The synthetic utility of the products was illustrated through Suzuki and Sonogashira cross-coupling reactions, offering a novel reaction procedure to access complex enamide derivatives. [ABSTRACT FROM AUTHOR]

2‐Cyano‐5,10,15,20‐tetraphenylporphyrin [H2TPPCN] (1) having cyano group at one of β‐pyrrolic positions using nucleophilic substitution reaction of tetrabutylammonium cyanide (TBACN) on free‐base 2‐nitro‐5,10,15,20‐tetraphenylporphyrin, and its oxidovanadium(IV) complex [VIVOTPPCN] (2) were synthesized in good yields. Both the porphyrins 1 and 2 have been characterized by UV‐Vis spectroscopy, mass spectrometry, and cyclic voltammetric techniques. Single crystal X‐Ray crystallography revealed quasi‐planar geometry for 1. Compounds 1 and 2 exhibited a red shift (λmax=7–9 nm) in the Soret band relative to [MTPP], where M=2H, VIVO owing to the electron‐withdrawing effect of the cyano group at the β‐position. The first oxidation (ΔE1/2=110–140 mV) and reduction potentials (ΔE1/2=220–260 mV) of 1 and 2 are anodically shifted relative to [MTPP] where M=2H, VIVO. Porphyrin 2 has been utilized as a catalyst for two reactions: epoxidation of olefins and bromination of phenols. The bromination of phenol using KBr/H2O2/HClO4 in water resulted in 100 % conversion with a TOF value as high as 19.6 s−1 in 0.5 h. Using H2O2/NaHCO3 in a CH3CN/H2O solvent mixture at 60 °C, epoxidation was carried out, and the highest conversion rate with a turnover frequency of 1.9 s−1 was achieved in the case of cyclohexene. Catalyst 2 was recovered successfully at the end of the reaction up to 5 cycles and had good thermal stability, indicating its industrial viability and applicability. Moreover, these cyano‐functionalized porphyrins could be further utilized for the generation of molecular self‐assemblies, post‐functionalization of porphyrin core and various applications. The current findings in this work present insights for a facile approach for the synthesis of β‐cyano functionalized porphyrin 1 and further shed light on the utility of its vanadyl complex 2 as an efficient catalyst for olefin epoxidation and phenol bromination reactions. [ABSTRACT FROM AUTHOR]

We present a novel, eco-friendly and one-pot approach for synthesizing unsymmetrical oxalamides with the aid of dichloroacetamide and amine/amides in the presence of CBr4 in a basic medium. The use of water as a potent supplement for the oxygen atom source and the detailed mechanism have been disclosed. Moreover, the protocol involves triple cleavage of CCl2Br and the formation of new C–O/C–N bonds, with the advantage of achieving selective bromination using CBr4 with good to excellent yield under mild conditions. The method also demonstrates promise for industrial use, as proven by its effective implementation in gram-scale synthesis conducted in a batch process, along with its utilization in a continuous-flow system. [ABSTRACT FROM AUTHOR]