Bromination of olefins with HBr and DMSO

An efficient and mild oxidative approach from thiols to sulfonyl derivatives with DMSO/HBr

A mild and practical method for synthesizing sulfonyl derivatives, which have a wide range of applications in pharmaceuticals, materials, and organic synthesis, was described through the oxidative functionalization of thiols with DMSO/HBr. The simple conditions, low cost and ready availability of DMSO/HBr, as well as the versatility of the transformations, make this strategy very powerful in synthesizing a variety of sulfonyl derivatives including sulfonamides, sulfonyl fluorides, sulfonyl azides, and sulfonates. Mechanistic studies revealed that DMSO served as the terminal oxidant, and HBr acted as both a nucleophile and a redox mediator to transfer the oxygen atom.

NH4OAc/DMSO-Promoted Benzylation of Pyrrolo[2,1-a]isoquinolines

Benzylation of pyrrolo[2,1-a]isoquinoline derivatives has been realized with various phenols by the use of ammonium acetate as a promoter (20 examples, up to 84% yield). DMSO served as the source of methylene and solvent. The employment of iron chloride as a catalyst can also afford the desired benzylated products in moderate to good yields (11 examples, up to a 74% yield).

Regiodivergent sulfonylation of terminal olefins via dearomative rearrangement

Sulfones are fascinating and highly used functional groups, but current syntheses still have limitations. Here, a regiodivergent transition metal-free approach towards sulfones [(E)-allylic sulfones and α-sulfonyl-methyl styrenes] is reported. The method employs commercially available olefins, bases, additives, solvents, and sodium sulfinates (RSO2Na) and produces adducts in good yields. Considering that up to 4 reactions (bromination, dearomative rearrangement, E2, and SN2) are happening, this approach is very efficient. The structures of key adducts were confirmed by X-ray crystallography.

Bromination of Pyrrolo[2,1-a]isoquinolines with Acetyl Bromide and Dimethyl Sulfoxide

A mild bromination of pyrrolo[2,1-a]isoquinolines has been achieved using acetyl bromide and dimethyl sulfoxide. A series of brominated pyrrolo[2,1-a]isoquinolines could be obtained in moderate to excellent yields (46-99%) at room temperature. This strategy can also be expanded to the facile bromination of polysubstituted pyrroles, indoles, electron-rich phenols, aniline, and 2-naphthol.

Mechanistic Details of Asymmetric Bromocyclization with BINAP Monoxide: Identification of Chiral Proton-Bridged Bisphosphine Oxide Complex and Its Application to Parallel Kinetic Resolution

The mechanism of our previously reported catalytic asymmetric bromocyclization reactions using 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) monoxide was examined in detail by the means of control experiments, NMR studies, X-ray structure analysis, and CryoSpray electrospray ionization mass spectrometry (ESI-MS) analysis. The chiral BINAP monoxide was transformed to a key catalyst precursor, proton-bridged bisphosphine oxide complex (POHOP·Br), in the presence of N-bromosuccinimide (NBS) and contaminating water. The thus-formed POHOP further reacts with NBS to afford BINAP dioxide and molecular bromine (Br₂) simultaneously in equimolar amounts. While the resulting Br₂ is activated by NBS to form a more reactive brominating reagent (Br₂─NBS), BINAP dioxide serves as a bifunctional catalyst, acting as both a Lewis base that reacts with Br₂─NBS to form a chiral brominating agent (P═O⁺─Br) and also as a Brønsted base for the activation of the substrate. By taking advantage of this novel concerted Lewis/Brønsted base catalysis by BINAP dioxide, we achieved the first regio- and chemodivergent parallel kinetic resolutions (PKRs) of racemic unsymmetrical bisallylic amides via bromocyclization.

Modification of Pyrrolo[2,1-a]isoquinolines and Pyrrolo[1,2-a]quinolines with Ammonium Acetate and Dimethyl Sulfoxide via Methylthiomethylation

An efficient methylthiomethylation of pyrroloisoquinolines and pyrroloquinolines has been reached by the use of ammonium acetate and dimethyl sulfoxide. Methylthiomethylated heterocycles can be obtained in moderate to good yields in most cases, while trace amounts to good yields of methylene-bridged products can be observed. Choice of DMSO activator and its amount have a great influence on the chemoselectivity of this process. It is worth noting that this process can also be scalable. Another feature of this process is that the product can be transformed to sulfone and sulfoxide easily.

DMSO-allyl bromide: a mild and efficient reagent for atom economic one-pot N-allylation and bromination of 2°-aryl amines, 2-aryl aminoamides, indoles and 7-aza indoles

A mixture DMSO-allyl bromide has been developed as a reagent for an atom economic one-pot N-allylation and aryl bromination under basic conditions. Utilizing this reagent, N-allylation-bromination of a number of 2°-aryl amines, aryl aminoamides, indoles, and 7-aza indoles has been achieved. The scope of the substrates and limitations, the synthetic utility of the products, and a plausible reaction mechanism have been proposed.

Dibrominated addition and substitution of alkenes catalyzed by Mn2(CO)10

A practical method for the dibromination of alkenes without using molecular bromine is consistently appealing in organic synthesis. Herein, we report Mn-catalyzed dibrominated addition and substitution of alkenes only with N-bromosuccinimide, producing a variety of synthetically valuable dibrominated compounds in moderate to high yields.

Lights and Shadows of DMSO as Solvent for Tin Halide Perovskites

In 2020 dimethyl sulfoxide (DMSO), the ever‐present solvent for tin halide perovskites, was identified as an oxidant for Sn^II. Nonetheless, alternatives are lacking and few efforts have been devoted to replacing it. To understand this trend it is indispensable to learn the importance of DMSO on the development of tin halide perovskites. Its unique properties have allowed processing compact thin‐films to be integrated into tin perovskite solar cells. Creative approaches for controlling the perovskite crystallization or increasing its stability to oxidation have been developed relying on DMSO‐based inks. However, increasingly sophisticated strategies appear to lead the field to a plateau of power conversion efficiency in the range of 10–15 %. And, while DMSO‐based formulations have performed in encouraging means so far, we should also start considering their potential limitations. In this concept article, we discuss the benefits and limitations of DMSO‐based tin perovskite processing.

Structural revision of the Mcl-1 inhibitor MIM1: synthesis and biological studies on ovarian cancer cells with evaluation of designed analogues

In the area of cancer research, the development of new and potent inhibitors of anti-apoptotic proteins is a very active and promising topic. The small molecule MIM1 has been reported earlier as one of the first selective inhibitors of the anti-apoptotic protein Mcl-1. In the present paper, we first revised the structure of this molecule based on extensive physicochemical analyses. Then we designed and synthesized a focused library of analogues for the corrected structure of MIM1. Next, these molecules were subjected to a panel of in cellulo biological studies, allowing the identification of dual Bcl-xL/Mcl-1 inhibitors, as well as selective Mcl-1 inhibitors. These results have been complemented by fluorescence polarization assays with the Mcl-1 protein. Preliminary structure-activity relationships were discussed and extensive molecular modelling studies allowed us to propose a rationale for the biological activity of this series of new inhibitors, in particular for the selectivity of inhibition of Mcl-1 versus Bcl-xL.

Formylation and Bromination of Pyrrolo[2,1-a]isoquinoline Derivatives with Bromoisobutyrate and Dimethyl Sulfoxide

We have developed an efficient formylation of pyrroloisoquinolines using bromoisobutyrate and dimethyl sulfoxide as carbonyl reagent. Various formylated pyrroloisoquinolines could be prepared in good yields (up to 94%). This formylation process can be easily scaled up to gram scale with good yield. In most cases of pyrroloisoquinolines without methoxy groups, the combination of bromoisobutyrate and dimethyl sulfoxide could act as a bromination reagent, delivering brominated pyrroloisoquinolines in acceptable to good yields (up to 82%).

Solvent and catalyst-free bromofunctionalization of olefins using a mechanochemical approach

Bromofunctionalizations of olefins are an important class of chemical transformations. N-Bromoimide reagents are commonly used in these reactions but catalysts and chlorinated solvents are often employed to achieve a reasonable reaction rate. In this report, we present a solvent and catalyst-free bromofunctionalization of olefins using mechanical force.

Efficient bromofunctionalization of olefins including bromolactonization, bromocycloetherification, and intermolecular bromoesterification were achieved under solvent and catalyst-free conditions using a mechanochemical approach.

Transition metal free, green and facile halogenation of ketene dithioacetals using a KX–oxidant system

A facile oxidative halogenation of α-oxo ketene dithioacetals is achieved by using a potassium halide and an oxidant combination under transition metal free conditions at ambient temperature.

Tracking down the brominated single electron oxidants in recent organic red-ox transformations: photolysis and photocatalysis

A wide range of organic and inorganic brominated compounds including molecular bromine have been extensively used as oxidants in many organic photo-redox transformations in recent years, an area of ever growing interest because of greener and milder approaches. The oxidation power of these compounds is utilized through both mechanistic pathways (by hydrogen atom transfer or HAT in the absence of a photocatalyst and a combination of single electron transfer or SET and/or HAT in the presence of a photocatalyst). Not only as terminal oxidants for regeneration of photocatalysts, but brominated reactants have also contributed to the oxidation of the reaction intermediate(s) to carry on the radical chain process in several reactions. Here in this review mainly the non-brominative oxidative product formations are discussed, carried out since the last two decades, skipping the instances where they acted as terminal oxidants only to regenerate photocatalysts. The reactions are used to generate natural products, pharmaceuticals and beyond.

Regioselective Monobromination of Phenols with KBr and ZnAl-BrO3--Layered Double Hydroxides

The regioselective mono-bromination of phenols has been successfully developed with KBr and ZnAl-BrO3--layered double hydroxides (abbreviated as ZnAl-BrO3--LDHs) as brominating reagents. The para site is much favorable and the ortho site takes the priority if para site is occupied. This reaction featured with excellent regioselectivity, cheap brominating reagents, mild reaction condition, high atom economy, broad substrate scope, and provided an efficient method to synthesize bromophenols.

Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts

Organosulfur compounds have long played a vital role in organic chemistry and in the development of novel chemical structures and architectures. Prominent among these organosulfur compounds are those involving a sulfur(IV) center, which have been the subject of countless investigations over more than a hundred years. In addition to a long list of textbook sulfur-based reactions, there has been a sustained interest in the chemistry of organosulfur(IV) compounds in recent years. Of particular interest within organosulfur chemistry is the ease with which the synthetic chemist can effect a wide range of transformations through either bond formation or bond cleavage at sulfur. This review aims to cover the developments of the past decade in the chemistry of organic sulfur(IV) molecules and provide insight into both the wide range of reactions which critically rely on this versatile element and the diverse scaffolds that can thereby be synthesized.

Metal-free, green and efficient oxidative α halogenation of enaminones by halo acid and DMSO

Metal free oxidative halogenation of N-aryl enaminones has been demonstrated using a DMSO–halo acid combination under mild reaction conditions. The present method is a straightforward approach and is also applied for the synthesis of chromenone derivatives in excellent yields.

Metal free, facile sulfenylation of ketene dithioacetals catalyzed by an HBr–DMSO system

A transition metal free, efficient, sulfenylation of ketene dithioacetals catalyzed by an HBr–DMSO system is achieved. This strategy employs inexpensive and readily available HBr and DMSO to provide a direct C–H bond sulfenylation with a broad range of aryl thiols. This sulfenylated product is also transformed for the synthesis of pyrazole derivatives in excellent yield.

Dimethyl sulfoxide as a “methylene” source: Ru(ii) photo-catalysed facile synthesis of acetals from alcohols

First photocatalytic synthesis of acetals using DMSO as a “methylene” source.

Metal-free Chlorothiolation of Alkenes using HCl and Sulfoxides

We report a novel method for the chlorothiolation of alkenes using HCl and sulfoxides to achieve the 1,2-difunctionalization of unactivated alkenes. The combination of our new HCl reagent (HCl/DMPU) with sulfoxides forms a unique chlorothiolation system. Both terminal and internal alkenes are suitable substrates. This method works at gram scale and is applicable in further synthetic elaborations.

Dibromination of alkenes with LiBr and H2O2 under mild conditions

Activation of H₂O₂ by LiBr and AcOH is efficiently achieved for dibromination of alkenes in high yields and selectivity.

Solution-Processed Cesium Hexabromopalladate(IV), Cs2PdBr6, for Optoelectronic Applications

Lead halide perovskites are materials with excellent optoelectronic and photovoltaic properties. However, some hurdles remain prior to commercialization of these materials, such as chemical stability, phase stability, sensitivity to moisture, and potential issues due to the toxicity of lead. Here, we report a new type of lead-free perovskite related compound, Cs₂PdBr₆. This compound is solution processable, exhibits long-lived photoluminescence, and an optical band gap of 1.6 eV. Density functional theory calculations indicate that this compound has dispersive electronic bands, with electron and hole effective masses of 0.53 and 0.85 m_e, respectively. In addition, Cs₂PdBr₆ is resistant to water, in contrast to lead-halide perovskites, indicating excellent prospects for long-term stability. These combined properties demonstrate that Cs₂PdBr₆ is a promising novel compound for optoelectronic applications.

Double C–S bond formation via C–H bond functionalization: synthesis of benzothiazoles and naphtho[2,1-d]thiazoles from N-substituted arylamines and elemental sulfur

An atom economic and environmentally friendly method for the synthesis of benzothiazoles and naphtho[2,1-d]thiazoles has been developed under metal-free conditions.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

A radical coupling reaction of DMSO with sodium arylsulfinates in air : mild utilization of DMSO as C1 resource for the synthesis of arylsulfonyl dibromomethane

A radical coupling reaction of DMSO with ArSO₂Na without the needs of anaerobic atmosphere to afford ArSO₂CHBr₂ is described.

Simple efficient one-pot synthesis of 5-hydroxymethylfurfural and 2,5-diformylfuran from carbohydrates

A one-pot procedure for the synthesis of DFF starting from mono-, di- or polysaccharides or from primary biomass has been developed. HMF is formed as intermediate and can also be isolated.

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

Although recent years have witnessed significant advances in the development of catalytic, enantioselective halofunctionalizations of alkenes, the related dihalogenation of olefins to afford enantioenriched vicinal dihalide products remains comparatively underdeveloped. However, the growing number of complex natural products bearing halogen atoms at stereogenic centers has underscored this critical gap in the synthetic chemist's arsenal. This Review highlights the selectivity challenges inherent in the design of enantioselective dihalogenation processes, and formulates a mechanism-based classification of alkene dihalogenations, including those that may circumvent the "classical" haliranium (or alkene-dihalogen π-complex) intermediates. A variety of metal and main group halide reagents that have been used for the dichlorination or dibromination of alkenes are discussed, and the proposed mechanisms of these transformations are critically evaluated.