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A Brønsted acid catalyzed C–H functionalization of vinyldiazoacetates with 3-hydroxyisoindolinone is developed. This methodology provides a general access to E -substituted isoindolinone vinyldiazo compounds in good yields and excellent diastereoselectivities with broad substrate generality under mild conditions, and with 4-substituted 2-diazo-3-butenoates produces fused bicyclic pyrrolidines. The reaction generally involves addition of the N -acyl ketiminium electrophile, formed from the 3-hydroxyisoindolinone, to the vinylogous position of the vinyldiazo compound resulting in vinyldiazonium ion intermediates that undergo deprotonation to new vinyldiazo compounds or ring closure to fused bicyclic pyrrolidines. [ABSTRACT FROM AUTHOR]

Trifluoromethoxylated molecules and selenylated compounds find a wide range of interesting applications, but separately. In order to combine the potential of these two motifs and to propose a new class of compounds, we have developed an electrophilic phenylseleno trifluoromethoxylation of alkenes, which leads to β-selenylated trifluoromethoxylated compounds or, upon subsequent reduction, to the trifluoromethoxylated ones.

Comprehensive Summary: Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time. Various selenium‐containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities. As the substrates were 1‐ethynyl naphthol derivatives, linear selenium‐containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive; in contrast, cyclic selenium‐containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time. Various selenium‐containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities. As the substrates were 1‐ethynyl naphthol derivatives, linear selenium‐containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive; in contrast, cyclic selenium‐containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid. [ABSTRACT FROM AUTHOR]

Two Mo(0) phosphenium complexes containing ancillary secondary phosphine ligands have been investigated with respect to their ability to participate in electrophilic addition at unsaturated substrates and subsequent P−H hydride transfer to "quench" the resulting carbocations. These studies provide stoichiometric "proof of concept" for a proposed new metal‐catalyzed electrophilic hydrophosphination mechanism. The more strongly Lewis acidic phosphenium complex, [Mo(CO)4(PR2H)(PR2)]+ (R=Ph, Tolp), cleanly hydrophosphinates 1,1‐diphenylethylene, benzophenone, and ethylene, while other substrates react rapidly to give products resulting from competing electrophilic processes. A less Lewis acidic complex, [Mo(CO)3(PR2H)2(PR2)]+, generally reacts more slowly but participates in clean hydrophosphination of a wider range of unsaturated substrates, including styrene, indene, 1‐hexene, and cyclohexanone, in addition to 1,1‐diphenylethylene, benzophenone, and ethylene. Mechanistic studies are described, including stoichiometric control reactions and computational and kinetic analyses, which probe whether the observed P−H addition actually does occur by the proposed electrophilic mechanism, and whether hydridic P−H transfer in this system is intra‐ or intermolecular. Preliminary reactivity studies indicate challenges that must be addressed to exploit these promising results in catalysis. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic synthesis. The organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile (such as elemental iodine and N‐iodosuccinimide (NIS)) as a typical ionic reaction, in which an iodonium ion is formed and then attacked by a nucleophile. However, in this article, we report a new and unusual reaction mode between an alkene and NIS; that is, a single electron transfer (SET) process occurs between these two reactants by forming an electron‐donor acceptor complex. Not only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry, it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic synthesis. The organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile (such as elemental iodine and N‐iodosuccinimide (NIS)) as a typical ionic reaction, in which an iodonium ion is formed and then attacked by a nucleophile. However, in this article, we report a new and unusual reaction mode between an alkene and NIS; that is, a single electron transfer (SET) process occurs between these two reactants by forming an electron‐donor acceptor complex. Not only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry, it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode. [ABSTRACT FROM AUTHOR]

Given the importance of difluoromethylated molecules for drug and agrochemical development, much attention has been drawn to the establishment of related synthetic protocols, as exemplified by the CF2H radical‐mediated catalytic difluoromethylation of alkenes. However, most of these difluoromethylations proceed under photocatalytic conditions, whereas those requiring thermal conditions are few. Herein, we developed a general and practical method of Cu‐catalyzed alkene difluoromethylation with difluoroacetic anhydride (DFAA) as a CF2H source, showing that the thus realized amino‐, allylic‐, and oxy‐difluoromethylations involve bis(difluoroacetyl) peroxide (BDFAP) in situ generated from DFAA and H2O2 and further demonstrating the occurrence of carbo‐difluoromethylation under catalyst‐free conditions. The obtained results pave the way to the simple and efficient synthesis of a broad range of difluoromethylated species and thus facilitate their practical applications, including those in medicinal and agricultural chemistry. Moreover, we probed the mechanisms of the observed transformations, rationalized the extraordinary fast decomposition of BDFAP compared to that of diacyl peroxides containing CF3 or CF2Cl groups, and performed DFT calculations to shed light on the low stability and decomposition mode of BDFAP. Finally, we examined the influence of fluorinated radical philicity on the reaction outcome. [ABSTRACT FROM AUTHOR]

Electrophilic addition reaction to alkynes is of fundamental importance in organic chemistry, yet the regiocontrol when reacting with unsymmetrical 1,2‐dialkyl substituted alkynes is often problematic. Herein, it is demonstrated that the rarely recognized β‐boron effect can confer a high level of site‐selectivity in several alkyne electrophilic addition reactions. A broad range of highly functionalized and complex organoborons are thus formed under simple reaction conditions starting from propargylic MIDA (N‐methyliminodiacetic acid) boronates. These products are demonstrated to be valuable building blocks in organic synthesis. In addition to the regiocontrol, this study also observes a drastic rate enhancement upon B(MIDA) substitution. Theoretical calculation reveals that the highest occupied molecular obital (HOMO) energy level of propargylic B(MIDA) is significantly raised by 0.3 eV, and the preferential electrophilic addition to the γ position is due to its higher HOMO orbital coefficient and more negative natural bond orbital (NBO) charge compared to the β position. This study demonstrates the potential of utilizing the β‐boron effect in stereoelectronic control of chemical transformations, which can inspire further research in this area. [ABSTRACT FROM AUTHOR]

The sulfatobetaine formation from epoxides and tertiary amine‐sulfur trioxide complexes was studied. It was revealed that heterocyclic tertiary amine‐sulfur trioxide complexes being the most electrophilic and reactive complexes produce sulfatobetaines in 15.5–62.6 % isolation yields, the aliphatic tertiary amine sulfur‐trioxide complexes failed to form the expected products. The presence of the amine taken in 5‐fold excess improves the isolation yields of the sulfatobetaines (52–100 %). [ABSTRACT FROM AUTHOR]

Abstract Electrophilic addition reaction to alkynes is of fundamental importance in organic chemistry, yet the regiocontrol when reacting with unsymmetrical 1,2‐dialkyl substituted alkynes is often problematic. Herein, it is demonstrated that the rarely recognized β‐boron effect can confer a high level of site‐selectivity in several alkyne electrophilic addition reactions. A broad range of highly functionalized and complex organoborons are thus formed under simple reaction conditions starting from propargylic MIDA (N‐methyliminodiacetic acid) boronates. These products are demonstrated to be valuable building blocks in organic synthesis. In addition to the regiocontrol, this study also observes a drastic rate enhancement upon B(MIDA) substitution. Theoretical calculation reveals that the highest occupied molecular obital (HOMO) energy level of propargylic B(MIDA) is significantly raised by 0.3 eV, and the preferential electrophilic addition to the γ position is due to its higher HOMO orbital coefficient and more negative natural bond orbital (NBO) charge compared to the β position. This study demonstrates the potential of utilizing the β‐boron effect in stereoelectronic control of chemical transformations, which can inspire further research in this area.

The demand for practical methods for the synthesis of novel fluoroalkyl molecules is increasing owing to their diverse applications. Our group has achieved efficient difunctionalizing fluoroalkylations of alkenes using fluorinated carboxylic anhydrides as user‐friendly fluoroalkyl sources. Fluorinated diacyl peroxide, prepared in situ from carboxylic anhydrides, enables the development of novel reactions when used as a radical fluoroalkylating reagent. In this account, we aim to provide an in‐depth understanding of the structure, bonding, and reactivity of fluorinated diacyl peroxides and radicals as well as their control in fluoroalkylation reactions. In the first part of this account, the physical properties and reactivity of diacyl peroxides and fluoroalkyl radicals are described. In the subsequent part, we categorize the reactions into copper‐catalyzed and metal‐free methods utilizing the oxidizing properties of fluorinated diacyl peroxides. We also outline examples and mechanisms. [ABSTRACT FROM AUTHOR]

Benzoxaborinines are intermediates en‐route to bicyclic boronates that are important active pharmaceutical ingredients (APIs). Herein, the haloboration of o‐alkynyl‐phenols using BX3 (X=Cl or Br) is disclosed as a route to form C4‐X‐benzoxaborinines with good functional group tolerance. Computational studies indicated that there are two similar in barrier mechanisms: (i) double alkyne haloboration followed by retro‐haloboration; (ii) concerted trans‐haloboration involving an exogenous chloride source. The C4‐halide in these benzoxaborinines is useful, with a one‐pot haloboration‐Negishi cross coupling protocol effective to form benzoxaborinines with an alkyl or an aryl at C4. Therefore this method is a useful addition to the toolbox for synthesising bicyclic‐boronates that are attracting increasing attention as APIs. [ABSTRACT FROM AUTHOR]

The electrophilic addition reactions of alkenes and the elimination reactions of alkyl halides are two fundamental reactions that undergraduates should master in basic organic chemistry course, but are rarely included in the laboratory course. The disconnection between theory and practice leads to the poor understanding of the reaction mechanisms. To address this disconnection in organic chemistry instruction, we design an experiment containing an electrophilic addition reaction and an elimination reaction. In this experiment, we use isopulegol as the starting material to synthesize the expensive R-citronellal in a one-pot two-step manner at room temperature through an electrophilic addition and a Grob fragmentation (a special elimination). The experiment features low cost of reagents, simple operation, mild reaction conditions and comprehensive skill training, therefore, it is a qualified teaching experiment that could help students deepen their understanding of theoretical knowledge while polishing their organic laboratory techniques. [ABSTRACT FROM AUTHOR]

For the first time reactions of acetylene generated in a two-chamber reactor with methyl diazoacetate, iodine and benzoyl chlorides were studied. Methyl 1H-pyrazole-3-carboxylate, (E)-1,2-diiodoethylene, (E)-1,2-dideutero-1,2-diiodoethylene, (2E)-1-aryl-3-chloroprop-2-en-1-ones, including D-labeled 3-chloro-2,3-dideutero-1-phenylprop-2-en-1-one were synthesized. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is regarded as a hazardous pollutant that exists widely in aquatic environments, posing a severe threat to human health. In this study, a vacuum ultraviolet (VUV) lamp emitting a hybrid of 254 nm and 185 nm light was used to degrade BPA. Results indicated that photolysis via 254 nm wavelength accounted for 24.93% for BPA decay, while indirect oxidation was responsible for 52.27% of decay. Results confirmed that the degradation of BPA under VUV illumination mainly occurred via photo-excited degradation and ·OH electrophilic addition reactions based on average local ionization energy (ALIE) calculation and density functional theory (DFT) calculations. Therefore, only light with a wavelength of 254 nm was able to induce the first three excited states of BPA, forming the electron transition type of n → π* from O atom to a single benzene ring and π → π* in the single benzene ring. Indirect oxidation by ·OH occurred as it preferentially attacked the C6 atom in BPA ring A. Moreover, the energy required for photo-excited degradation was about twofold than that of ·OH electrophilic addition reactions. [ABSTRACT FROM AUTHOR]

We have studied the enantioselective transannular aminohalogenation reaction of unsaturated medium‐sized cyclic benzosulfonamides by using both chiral Brønsted acid and phase‐transfer catalysis. Under optimized conditions, a variety of bicyclic adducts can be obtained with good yields and high enantioselectivities. The mechanism of the reaction was also studied by using computational tools; we observed that the reaction involves the participation of a conformer of the nine‐membered cyclic substrate with planar chirality in which the stereochemical outcome is controlled by the relative reactivity of the two pseudorotational enantiomers when interacting with the chiral catalyst. [ABSTRACT FROM AUTHOR]

A new approach for the synthesis of 3‐organoselanyl‐benzo[b]chalcogenophenes promoted by trichloroisocyanuric acid is reported. The reaction was carried out with electrophilic selenium species which were generated in situ by the reaction between trichloroisocyanuric acid and diorganyl diselenides using ethanol as solvent. The developed method uses mild reaction conditions and was efficient for the synthesis of different 3‐organoselanyl‐benzo[b]chalcogenophenes in a good to excellent yields. Analysis of 77Se NMR spectroscopy indicates that the electrophilic PhSeCl was formed in situ and a plausible reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

The application of an alkyne cyclotrimerization regime with an [Fe(salen)]2‐μ‐oxo (1) catalyst to triphenylmethylphosphaalkyne (2) yields gram‐scale quantities of 2,4,6‐tris(triphenylmethyl)‐Dewar‐1,3,5‐triphosphabenzene (3). Bulky lithium salt LiHMDS facilitates a rearrangement of 3 to the 1,3,5‐triphosphabenzene valence isomer (3′), which subsequently undergoes an intriguing phosphorus migration reaction to form the ring‐contracted species (3′′). Density functional theory calculations provide a plausible mechanism for this rearrangement. Given the stability of 3, a diverse array of unprecedented transformations was investigated. We report novel crystallographically characterized products of successful nucleophilic/electrophilic addition and protonation/oxidation reactions. [ABSTRACT FROM AUTHOR]

A metal‐free, economical and effective method for intramolecular haloamination/cyclization of non‐functionalized olefins was developed. In the presence of K2S2O8 and sodium halide, 2‐allyl aniline can be converted into corresponding 2‐iodo, bromo and chloromethyl indolines skeleton compounds in good to excellent yields. Mechanism research suggested that the reaction didn't involve radical addition pathway. Introduction [ABSTRACT FROM AUTHOR]

A C(5)−H remote functionalization of 8‐aminoquinoline derivatives with para‐quinone methides, affording direct access to unsymmetrical tri(hetero)arylmethanes in 69–96 % yield is described. This method provides diverse tri(hetero)arylmethanes with a broad scope and in a regioselective manner. The transformation works well with electron‐rich and electron‐deficient substrates. [ABSTRACT FROM AUTHOR]

Organic thiocyanates widely exist in natural products, and act as important precursors for organic synthesis. An efficient dithiocyanation of alkynes with N‐thiocyanato‐dibenzenesulfonimide (NTSI) as the SCN+ cation and ammonium thiocyanate as the SCN‐ anion sources has been developed. Highly active electrophilic reagent NTSI could react with various types of alkynes to build C(sp2)−SCN bond to provide a variety of dithiocyanato olefin compounds under simple and mild conditions. Trace amount of water is beneficial to the dissociation of ammonium thiocyanate, which makes the SCN‐ anion easier to participate in the reaction. The protocol owns a broad substrates scope including terminal and internal, alkyl and aryl alkynes, excellent functional group tolerance and good regioselectivity. [ABSTRACT FROM AUTHOR]

3-Aryl-4-hydroxy-1-methyl-3,4-dihydroquinazolin-2(1 H)-ones were synthesized by reduction of 3-aryl-1-methylquinazoline-2,4(1 H ,3 H)-diones with sodium triethylborohydride and studied as precursors of N -acyliminium cations that were expected to be trapped with various alkenes as (4+2)-cycloadducts. Unsubstituted 3-aryl-4-hydroxy-1-methyl-3,4-dihydroquinazolin-2(1 H)-ones in the presence of BF3 ·Et2 O failed to produce the desired cycloadducts probably due to a homooligomerization reaction involving N -acyliminium intermediates. To prevent this side reaction, we found it necessary to introduce substituents at both positions C6 and C8 of the quinazoline ring and C4′ of the 3-phenyl substituent. Utilizing bromine atoms as substituents at C6 and C8, N -acyliminium cations generated from 3-aryl-6,8-dibromo-4-hydroxy-1-methyl-3,4-dihydroquinazolin-2(1 H)-ones in the presence of BF3 ·Et2 O smoothly reacted with such alkenes as indene, acenaphthylene, styrene, α-methylstyrene to give new quinolino[1,2- c ]quinazolin-6-one derivatives with high regio- and stereoselectivity. Density functional theory calculations were performed at the M06-2x/cc-pVDZ level to obtain an insight into the mechanism of the (4+2)-cycloaddition reaction of quinazoline-derived N -acyliminium cations to alkenes. [ABSTRACT FROM AUTHOR]

Limonene (1-methyl-4-(1-methylethenyl)-cyclohexene) is one of the most widespread monocyclic terpenes, being both a natural and industrial compound. It is widely present in the environment, including in water supplies. Therefore, it may be subjected to aqueous chlorination at water treatment stations during drinking water preparation. Besides, being a component of numerous body care and cosmetic products, it may present at high levels in swimming pool waters and could also be subjected to aqueous chlorination. Laboratory experiments with aqueous chlorination of D-limonene demonstrated the prevalence of the conjugated electrophilic addition of HOCl molecule to the double bonds of the parent molecule as the primary reaction. The reaction obeys the Markovnikov rule, as the levels of the corresponding products were higher than those of the alternative ones. Fragmentation pattern in conditions of electron ionization enabled the assigning of the structures for four primary products. The major products of the chlorination are formed by the addition of two HOCl molecules to limonene. The reactions of electrophilic addition are usually accompanied by the reactions of elimination. Thus, the loss of water molecules from the products of various generations results in the reproduction of the double bond, which immediately reacts further. Thus, a cascade of addition-elimination reactions brings the most various isomeric polychlorinated species. At a ratio of limonene/active chlorine higher than 1:10, the final products of aqueous chlorination (haloforms) start forming, while brominated haloforms represent a notable portion of these products due to the presence of bromine impurities in the used NaOCl. It is worth mentioning that the bulk products of aqueous chlorination are less toxic in the bioluminescence test on V. fischeri than the parent limonene. [ABSTRACT FROM AUTHOR]

Trifluoromethoxylated molecules and selenylated compounds find a wide range of interesting applications, but separately. In order to combine the potential of these two motifs and to propose a new class of compounds, we have developed an electrophilic phenylseleno trifluoromethoxylation of alkenes, which leads to β-selenylated trifluoromethoxylated compounds or, upon subsequent reduction, to the trifluoromethoxylated ones., (Copyright © 2024, Delobel et al.)

Leloir glycosyltransferases play an important role in many fundamental processes of living systems by catalyzing biological glycosylations. Neutral analogues of nucleotide sugars, as potential donor‐substrate inhibitors of Leloir glycosyltransferases, are of prime interest in medicinal chemistry. We report the development of S‐linked sugar‐nucleotide analogues by replacing the α‐O‐pyrophosphate bridge with an electroneutral ethyl or propyl linker by radical mediated hydrothiolation of 2‐substituted glycals and olefinic nucleoside analogues. UDP‐glucose and UDP‐GlcNAc analogues were assembled from 2‐substituted glycals, 1,2‐ethanedithiols and uridine 4'‐exomethylene derivative by two subsequent thio‐click reactions. Morpholino type mimetics of UDP‐, GDP‐ and CMP‐sugars were constructed by photoinitiated additions of 1‐thiosugars (Glc, GlcNAc, Gal, Man) and 2‐thio‐Neu5Ac onto N‐allyl morpholinos. [ABSTRACT FROM AUTHOR]

A new metal‐free hydrohalogenation method for alkynes has been developed, which proceeds through a pseudo‐intramolecular process. In this reaction, ethynylaniline serves as a substrate to quantitatively form an anilinium salt upon treatment with hydrochloric acid. The spatial proximity facilitates the efficient electrophilic addition of HCl to the ethynyl group in syn‐mode, affording the corresponding chloroalkene without overaddition. This protocol was applied to HBr and HI, and the corresponding bromo‐ and iodoalkenes were obtained, respectively. The obtained chloroalkene was converted to tri‐substituted alkenes possessing different aryl/alkynyl groups through Pd‐catalyzed cross‐coupling reactions. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A TEMPO catalyzed cross‐dihalogenation reaction was established via redox‐regulation of the otherwise complex system of dual electrophilic X+ reagents. Formally, the ICl, BrCl, I2 and Br2 were generated in‐situ, which enabled high regio‐ or stereoselective access to a myriad of iodochlorination, bromochlorination and homo‐dihalogenation products with a wide spectrum of functionalities. With its mild conditions and operational simplicity, this method could enable wide applications in organic synthesis, which was exemplified by divergent synthesis of two pharmaceuticals. Detailed mechanistic investigations via radical clock reaction, pinacol ring expansion and Hammett experiments were conducted, which confirmed the intermediacy of halonium ion. In addition, a dynamic catalytic model based on the versatile catalytic role of TEMPO was proposed to explain the selective outcomes. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The intramolecular cyclization of 2‐alkynylanilines mediated by DMSO/SOCl2 was found to afford biologically interesting 3‐methylthioindoles, which are rarely obtained by the exiting methods. DMSO could also be replaced with its deuterated counterpart, enabling the method applicable to the construction of indole skeleton bearing a SCD3 moiety at its 3‐position. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The intramolecular cyclization of 2‐alkynylanilines mediated by DMSO/SOCl2 was found to afford biologically interesting 3‐methylthioindoles, which are rarely obtained by the exiting methods. DMSO could also be replaced with its deuterated counterpart, enabling the method applicable to the construction of indole skeleton bearing a SCD3 moiety at its 3‐position. [ABSTRACT FROM AUTHOR]

Limonene (1-methyl-4-(1-methylethenyl)-cyclohexene) is one of the most widespread monocyclic terpenes, being both a natural and industrial compound. It is widely present in the environment, including in water supplies. Therefore, it may be subjected to aqueous chlorination at water treatment stations during drinking water preparation. Besides, being a component of numerous body care and cosmetic products, it may present at high levels in swimming pool waters and could also be subjected to aqueous chlorination. Laboratory experiments with aqueous chlorination of D-limonene demonstrated the prevalence of the conjugated electrophilic addition of HOCl molecule to the double bonds of the parent molecule as the primary reaction. The reaction obeys the Markovnikov rule, as the levels of the corresponding products were higher than those of the alternative ones. Fragmentation pattern in conditions of electron ionization enabled the assigning of the structures for four primary products. The major products of the chlorination are formed by the addition of two HOCl molecules to limonene. The reactions of electrophilic addition are usually accompanied by the reactions of elimination. Thus, the loss of water molecules from the products of various generations results in the reproduction of the double bond, which immediately reacts further. Thus, a cascade of addition-elimination reactions brings the most various isomeric polychlorinated species. At a ratio of limonene/active chlorine higher than 1:10, the final products of aqueous chlorination (haloforms) start forming, while brominated haloforms represent a notable portion of these products due to the presence of bromine impurities in the used NaOCl. It is worth mentioning that the bulk products of aqueous chlorination are less toxic in the bioluminescence test on V. fischeri than the parent limonene.

The dihalogenation of alkenes is one of the classic reactions in organic chemistry and a prime example of an electrophilic addition reaction. The often observed anti‐selectivity in this addition reaction can be explained by the formation of a haliranium‐ion intermediate. Although dihalogenations have been studied for more than a century, the development of reagent‐controlled, enantioselective dihalogenation has proved to be very difficult. Only recently, significant progress has been achieved. In this review, an overview on current method development in enantioselective dihalogenation is provided and mechanistic aspects that render this transformation challenging are discussed. [ABSTRACT FROM AUTHOR]

This review compiles and summarizes approaches to the preparation of heterocyclic systems containing sulfur atoms based on the reactions of disulfur dichloride which acts as an electrophilic reagent. It is shown that as a result of these transformations heterocycles with different numbers of sulfur atoms can be synthesized: 1,2,5-thiadiazoles, 1,2- and 1,4-thiazines, 1,2-dithiols, 1,2,3-dithiazoles, 1,2,3,4,5-pentathiepines, 1,2,3,4,5,6,7-heptathiocanes, and many others. The yields of the products of these reactions depend to a significant extent on the ratio of the reactants, the nature of the solvent, the base used, and the temperature. The exceptional role of disulfur dichloride in the synthesis of various sulfur-containing heterocycles is shown. [ABSTRACT FROM AUTHOR]

N -Phenyl- N -triflylpropiolamides react with iodine chloride or iodine bromide by an intramolecular electrophilic ipso -halocyclization/nucleophilic halide addition sequence to furnish cyclohexadiene-spiro-γ-lactams. These products can undergo cleavage of the amide bond with primary amines and of the N–Cspiro bond with secondary amines, leading to N -alkyl-2-iodo-3-phenylacrylamides and N -(4-halophenyl)-2-iodo-3-(2-triflylamino)phenylacrylamides, respectively. [ABSTRACT FROM AUTHOR]

1-Carboxymethyl-5-fluoro-5-halogeno-6-hydroxy-5,6-dihydrouracils and 1-carboxymethyl- 5-fluoro-6-hydroxy-5-nitro-5,6-dihydrouracil were synthesized in high yields by oxidative halogenation or nitration of 1-carboxymethyl-5-fluorouracil. Oxidative halogenation or nitration of 5-fluoro-1-(methoxycarbonylmethyl)uracil in acidic media results in the addition of the corresponding groups at the C(5) atom of uracil and simultaneous hydrolysis of the ester group. Bimolecular ions of the obtained compounds were detected in the negative ion mass spectra. [ABSTRACT FROM AUTHOR]

An alternative method for the preparation of 2′-bromo- (5b) and 2′-iodo- (5c) 1′,2′-unsaturated uracil nucleosides has been developed. The protocol was on the basis of the syn-elimination of pivalic acid from 2′-bromo-(7a,b) and 2′-iodo-(9a,b) 1′-pivaloyloxy-2′-deoxyuridine derivatives, which were derived from the halo-pivaloyloxylation of 3′,5′-bis-O-TBDMS-1′,2′-unsaturated uridine 1. Compounds 5b and 5c were shown to serve as versatile synthons for the respective 2′-C-branched 1′,2′-unsaturated uracil nucleosides, through palladium-catalyzed cross-coupling or halogen-lithium exchange reactions. [ABSTRACT FROM AUTHOR]

In this paper, we highlight some addition/cycloaddition reactions of allenylphosphonates and allenylphosphine oxides, mostly based on the work done in our laboratory. Thus the electrophilic addition of iodine monochloride (ICl) with allenylphosphine oxides affords cyclic phosphonium salts rather than γ-chloro-β-iodovinylphosphine oxides (NMR, HRMS, X-ray) that exhibit rather unusual downfield shifts in the 31P NMR spectra. These compounds undergo hydrolysis to afford γ-hydroxy-β-iodovinylphosphine oxides; the hydroxymethyl group in these compounds can be oxidized by Dess-Martin periodinane to afford the corresponding aldehyde-substituted vinylphosphine oxides. A [2+2] cycloaddition product of an allenylphosphonate has also been structurally characterized. Other reactions that are highlighted include those leading to (Z)/(E)-β-aminovinylphosphonates, β-ketophosphonates (and their utility in Horner-Wadsworth-Emmons reaction), indolyl/furanyl/isocoumaranyl/naphthyl phosphine oxides, thiophosphorylated phosphonates and azo-substituted coumarin phosphonates. [ABSTRACT FROM AUTHOR]

Various kinetic studies of the addition of hydrogen halides to alkenes were carried out in the 1930s, 1940s, and 1970s. Since then, there have been theoretical analyses of several aspects of alkene reactivity and regioselectivity during hydrohalogenation. A few works have studied the influence of the hydrogen halide when it is acting as a catalyst (as well as a reactant) under third-order kinetics. However, there has not been any theoretical investigation of the possibility that there is a carbocation intermediate in the contact ion pair. Therefore, we revisited the mechanistic aspects of this reaction at different levels of theory and using IRC (in a gaseous medium) and ONIOM (with an explicit solvent model). We found that (i) there is only one transition state (one energy barrier) for all possible reaction mechanisms in an apolar medium, (ii) there is no carbocation intermediate when a hydrohalogenation reaction is performed in apolar and polar protic media, (iii) hydrochlorination in apolar and polar protic media occurs through an asynchronous concerted mechanism (not through the stepwise mechanism described in undergraduate/graduate literature), and (iv) there are three possible competing mechanisms (with second-, third-, and fourth-order kinetics) in an apolar medium; the mechanism with fourth-order kinetics has the smallest energy barrier, while that with second-order kinetics (a mechanism in which the hydrogen halide does not also act as a catalyst) has the highest energy barrier. [ABSTRACT FROM AUTHOR]

A systematic screening study of the exohedral reactivity of the reduced fullerenes (fullerenides) C602− and C60⋅− is reported. These doubly and singly negatively charged carbon cages were prepared by two‐fold reduction of C60 with potassium, leading to K2C60, or by in situ monoreduction with the radical anion of benzonitrile PhCN⋅−, respectively. Several series of electrophiles, including geminal and distant dihalides, benzyl bromides, and diazonium compounds, were employed as addition partners. In general, the investigated bromides proved to be the most suitable reaction partners. A series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns, depending on the precise architecture and the steric demand of the addends, were synthesized and fully characterized. Some of the reaction products are unprecedented and inaccessible forms of neutral C60. The fullerenide chemistry presented here closely resembles related reactions of graphenides and carbon nanotubides, which are the most powerful methods for the functionalization of these macromolecular forms of synthetic carbon allotropes (SCAs). Activation of C60 by negative charging represents a little explored concept of fullerene chemistry, providing both new insights of fullerene reactivity itself and new types of exohedral derivatives. New additions to the family: Insights into the reductive functionalization of fullerenes and its application for preparing highly sophisticated fullerene architectures including an unprecedented 1,4‐cycloadduct are presented. Investigations on the exohedral reactivity of fullerenides and the scope of different electrophiles as addition partners leading to a series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns are reported. [ABSTRACT FROM AUTHOR]

A systematic screening study of the exohedral reactivity of the reduced fullerenes (fullerenides) C602− and C60⋅− is reported. These doubly and singly negatively charged carbon cages were prepared by two‐fold reduction of C60 with potassium, leading to K2C60, or by in situ monoreduction with the radical anion of benzonitrile PhCN⋅−, respectively. Several series of electrophiles, including geminal and distant dihalides, benzyl bromides, and diazonium compounds, were employed as addition partners. In general, the investigated bromides proved to be the most suitable reaction partners. A series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns, depending on the precise architecture and the steric demand of the addends, were synthesized and fully characterized. Some of the reaction products are unprecedented and inaccessible forms of neutral C60. The fullerenide chemistry presented here closely resembles related reactions of graphenides and carbon nanotubides, which are the most powerful methods for the functionalization of these macromolecular forms of synthetic carbon allotropes (SCAs). Activation of C60 by negative charging represents a little explored concept of fullerene chemistry, providing both new insights of fullerene reactivity itself and new types of exohedral derivatives. New additions to the family: Insights into the reductive functionalization of fullerenes and its application for preparing highly sophisticated fullerene architectures including an unprecedented 1,4‐cycloadduct are presented. Investigations on the exohedral reactivity of fullerenides and the scope of different electrophiles as addition partners leading to a series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns are reported. [ABSTRACT FROM AUTHOR]

Front Cover Picture: Catalytic Difluoromethylation of Alkenes with Difluoroacetic Anhydride: Reactivity of Fluorinated Diacyl Peroxides and Radicals (Adv. Keywords: Alkenes; Electrophilic addition; Fluorine; Peroxides; Radicals EN Alkenes Electrophilic addition Fluorine Peroxides Radicals 3553 3553 1 11/10/23 20231107 NES 231107 The front cover picture illustrates the difluoromethylation of alkenes with bis(difluoroacetyl) peroxide (BDFAP), which is easily preparable from difluoroacetic anhydride and hydrogen peroxide. Alkenes, Electrophilic addition, Fluorine, Peroxides, Radicals. [Extracted from the article]

Graphical abstract Highlights • Design, synthesis and stereoselective study of a novel heterobifunctional chiral auxiliary. • Structure with two reaction sites that could give rise two distinct groups of opposite stereochemistry. • Highly programmable stereoselective nucleophilic and electrophilic additions. • Potential access to tertiary alcohols and derivatives in high optical purity. Abstract The synthesis and diastereoselective performance of the pseudo C 2 -symmetric dodecaheterocycle 3 in nucleophilic and electrophilic reactions are reported. Compound 3 proved to be a highly diastereoselective template to generate a pair of enantiomeric moieties within its structure in a programmed manner. Hence, this study describes the synthesis of a novel potential heterobifunctional chiral auxiliary. [ABSTRACT FROM AUTHOR]

Tribromomethyl ketone and tribromovinyl derivatives were selectively prepared from the decarboxylative tribromination. The reaction between propiolic acid derivatives and dibromoisocyanuric acid (DBCA)/H2O afforded predominantly a tribromomethyl ketone derivative in the presence of AgOAc (10 mol%). When the same reaction was conducted with 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) instead of AgOAc, tribromovinyl derivatives were exclusively formed in good yields. It was found that ethynyl bromide is an intermediate. [ABSTRACT FROM AUTHOR]