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This manuscript describes the development of alkyne addition to the aziridine moiety of aziridinoquinoxalines using dual Ir(III)/Cu(I) catalytic system under green light‐emitting diode (LED) photolysis (λmax=525 nm). This mild method features high levels of chemo‐ and regioselectivity and was used to generate 30 highly functionalized substituted dihydroquinoxalines in 36–98 % yield. This transformation was also carried asymmetrically using phthalazinamine‐based chiral ligand to provide 9 chiral addition products in 96 : 4 to 86 : 14 e.r. The experimental and quantum chemical explorations of this reaction suggest a mechanism that involves Ir(III)‐catalyzed triplet energy transfer followed by a ring‐opening reaction ultimately leading to the formation of azomethine ylide intermediates. These azomethine intermediates undergo sequential protonation/copper(I) acetylide addition to provide the products. [ABSTRACT FROM AUTHOR]

Multicomponent reactions provide an excellent approach toward quaternary carbon centres utilizing convergent chemical reactions in a highly selective manner under one‐pot conditions. The reactivity of substrates and metal catalysts is carefully controlled, precluding the formation of side‐products. In this context, transition metal catalyzed reactions of onium ylides generated via diazo precursors and nucleophiles with a third component (an electrophile) have garnered significant attention. Using an allylic precursor as the electrophilic partner provides opportunities to construct all‐carbon quaternary centres. Furthermore, the presence of an allyl fragment in the multicomponent product serves as a pivotal handle for carrying out subsequent modifications. Several recent studies have employed Rh, Pd, and dual Rh/Pd catalytic systems in multicomponent reactions involving allylic alkylation that proceed via a synergistic or relay pathway. Although not significantly successful, in a few cases, asymmetric induction is achieved through chiral phosphoric acids or chiral phosphine ligands. Limited substrate and catalyst scope and the underlying mechanistic complexities have posed formidable challenges, slowing the advancement of asymmetric reactions. This review provides details of multicomponent reactions using readily available substrates like diazo compounds, allylic carbonates, and nucleophiles (R‐OH, R‐NH2,,etc.) forming complex organic compounds. Our primary objective is to discuss the mechanistic issues that may facilitate the progress in asymmetric reactions in this field. [ABSTRACT FROM AUTHOR]

The article explores recent advancements in the asymmetric Doyle-Kirmse reaction, a chemical reaction that produces chiral sulfides. It discusses different strategies and catalysts used to achieve high enantioselectivity in the reaction, as well as the role of chiral metal-bound ylides in controlling the stereoselectivity. The text also highlights the challenges and future directions for further development in this area. Overall, the article provides valuable insights into the current state and potential future advancements in this field of research. [Extracted from the article]

Novel examples for dipolar cycloaddition of isoquinolinium ylides to nitriles leading to new imidazo[2,1‐a]isoquinolines were described and the potential of this reaction in synthetic chemistry was explored. As a by‐product of this research, a number of N‐substituted, 3,4‐dihydro‐1H‐isoquinoline‐1‐carbonitriles were synthesized by a simple, efficient reaction of a series of isoquinolinium bromides and ethyl cyanoformate in the presence of triethylamine. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic representation of polarity, rate constant of reaction and barrier activation for the competitive channels- 1,2,3-triazoles products P3 and P4. Highlights • Mechanism and selectivity of [3 + 2] cycloaddition between CF3-ynone and azide ylide have been performed. • High selectivity of this 32CA reaction depends extremely to the polarity. • Activation energy of the most preferred cycloadduct decreases substantially according to the elevation of dielectric constant. • The predominance of the major product was confirmed by the presence of more stabilizing interactions. • This 32CA reaction being classified as a non-concerted two-stage one step mechanism. Abstract The goal of the present study is to make a comprehension of the connection between selectivity and polarity, in that fact this reaction process was studied in presence of toluene, THF and DMSO solvent through Molecular Electron Density Theory (MEDT) at the B3LYP/6-31+G(d,p) computational level. A remarkable predominance of 4-trifluoroacetyl-1,2,3-triazoles derivatives (P3) has been generated via [3 + 2] cycloaddition between CF3-ynone and azide ylide, rationalized by the electrophilic P+ and nucleophilic P− Parr functions at the reactive sites of reagents, affording the N3-C1 regioselectivity observed experimentally. Furthermore, an exploration of the relative energies of reaction, Gibbs free energy and barrier activation profile obviously evidences that experimentally isolated P3 is the most reachable product of this reaction, in good to excellent yield with respect to the increase of polarity. Moreover, ELF topology analysis of the most stable product demonstrates that the formation of new bonds appears to be directed through two dissimilar fashions, the first is formed by donation of some nitrogen non-bonding electron-density to the carbon pseudoradical center and, the second is formed by sharing nitrogen non-bonding electron-density and a carbon pseudoradical center via a non-concerted two-stage one-step molecular mechanism. [ABSTRACT FROM AUTHOR]

The reaction of SIPr, [1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene] (1), with C6F6 led to the formation of an unprecedented mesoionic compound (2). The formation of 2 is made accessible by deprotonation of the SIPr backbone with simultaneous elimination of HF. The C−F bond para to the imidazolium ring in 2 is only of 1.258(4) Å, which is the one of the shortest structurally authenticated C−F bonds known to date. The liberation of HF during the reaction is unequivocally proved by the addition of one more equivalent of SIPr, which leads to the imidazolium salt with the HF2− anion. To functionalize 2, the latter reacted with B(C6F5)3 to give an unusual donor–acceptor compound, where the fluoride atom from the C6F5 moiety coordinates to B(C6F5)3 and the carbanion moiety remains unaffected. Such coordination susceptibility of the fluoride atom of a nonmetallic system to a main‐group Lewis acid (Fnon‐metal→BR3) is quite unprecedented. Just a sip: Combination of the saturated N‐heterocyclic carbene 1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene (SIPr) and C6F6 led to a mesoionic compound, generated by C−F bond activation and deprotonation of the SIPr backbone. The reaction of the mesoionic compound with B(C6F5)3 afforded an adduct where the fluoride atom from the C6F5 moiety coordinates to B(C6F5)3. [ABSTRACT FROM AUTHOR]

The reaction of SIPr, [1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene] (1), with C6F6 led to the formation of an unprecedented mesoionic compound (2). The formation of 2 is made accessible by deprotonation of the SIPr backbone with simultaneous elimination of HF. The C−F bond para to the imidazolium ring in 2 is only of 1.258(4) Å, which is the one of the shortest structurally authenticated C−F bonds known to date. The liberation of HF during the reaction is unequivocally proved by the addition of one more equivalent of SIPr, which leads to the imidazolium salt with the HF2− anion. To functionalize 2, the latter reacted with B(C6F5)3 to give an unusual donor–acceptor compound, where the fluoride atom from the C6F5 moiety coordinates to B(C6F5)3 and the carbanion moiety remains unaffected. Such coordination susceptibility of the fluoride atom of a nonmetallic system to a main‐group Lewis acid (Fnon‐metal→BR3) is quite unprecedented. Just a sip: Combination of the saturated N‐heterocyclic carbene 1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene (SIPr) and C6F6 led to a mesoionic compound, generated by C−F bond activation and deprotonation of the SIPr backbone. The reaction of the mesoionic compound with B(C6F5)3 afforded an adduct where the fluoride atom from the C6F5 moiety coordinates to B(C6F5)3. [ABSTRACT FROM AUTHOR]

Studies the chemical reaction between HCHO and CCI using a high level of theory. Performance of geometry optimizations; Performance of single cluster calculations using the coupled-cluster; Reaction and activation energies; Existence of the ylide as a stable species having a transient character.

A ruthenium‐catalyzed direct mono‐C−H functionalization/annulation cascade reaction of benzimidates and sulfoxonium ylides has been developed. The reaction proceeds smoothly with a broad range of substrates, giving access to a variety of isoquinoline derivatives in moderate to good yields using an organic acid additive under oxidant free conditions. [ABSTRACT FROM AUTHOR]

A highly diastereoselective cyclopropanation of α,β,γ,δ‐unsaturated pyrazolones has been disclosed. This method allows for construction of a vinylcyclopropane‐fused pyrazolone framework via a 1,6‐addition/substitution sequence providing excellent regio‐ and chemoselectivity, good yields, broad functional group tolerance and gram‐scale capacity. Moreover, the subsequent transformation of derivatives demonstrates great potential in building useful synthetic architectures. [ABSTRACT FROM AUTHOR]

Abstract: A synergistic‐catalysis‐enabled reaction of 2‐indolymethanols with oxonium ylides has been established that makes use of a three‐component reaction between 3‐diazooxindoles, alcohols, and 2‐indolymethanols under the cooperative catalysis of a metal complex and a Brønsted acid. This reaction has not only provided a new approach for the construction of 3‐indolyl‐3‐alkoxy oxindole scaffolds by utilizing the C3‐electrophilicity of an indole, but it is also the first example of a nucleophilic addition of a metal‐associated ylide to 2‐indolylmethanols. In addition, this reaction also includes a rarely reported trapping of onium ylides with aryl electrophiles. [ABSTRACT FROM AUTHOR]

A concise synthesis of new polysubstituted pyrazoles containing a phosphorane is achieved from readily available organic compounds. This C-H bond functionalization is an efficient means of selectively substituting 4-position of pyrazole to produce a five-membered aromatic ring with a chain containing ylide moiety. This protocol requires no additional catalyst and can be used for other pyrazoles including different substituents. [ABSTRACT FROM AUTHOR]

A one-pot alkylation-halogenation of ketosulfoxonium ylides in the presence of alkyl halides is described. The method furnishes several gem-difunctionalized haloketones (an alkyl and F, Cl, Br, or I) in good yields. Replacing alkyl halides with a mixture of electrophilic halogen species and various halide anions led to gem-dihalogenated ketones containing a combination of the same or two different halogens. Kinetic isotopic effects as well as reaction kinetic experiments give insight to the mechanism of these reactions. [ABSTRACT FROM AUTHOR]

The reaction of (C5Me5)2Th(CH3)2 with the phosphonium salts [CH3PPh3]X (X=Cl, Br, I) was investigated. When X=Br and I, two equivalents of methane are liberated to afford (C5Me5)2Th[CHPPh3]X, rare terminal phosphorano-stabilized carbenes with thorium. These complexes feature the shortest thorium-carbon bonds (≈2.30 Å) reported to date, and electronic structure calculations show some degree of multiple bonding. However, when X=Cl, only one equivalent of methane is lost with concomitant formation of benzene from an unstable phosphorus(V) intermediate, yielding (C5Me5)2Th[κ2-(C,C′)-(CH2)(CH2)PPh2]Cl. Density functional theory (DFT) investigations of the reaction energy profiles for [CH3PPh3]X, X=Cl and I showed that in the case of iodide, thermodynamics prevents the production of benzene and favors formation of the carbene. [ABSTRACT FROM AUTHOR]

The synthesis of diastereo- and enantiopure heterocyclic molecules via catalytic asymmetric 1,3-dipolar cycloaddition reaction between azomethine ylides, generated in situ from α-amino acid-derived iminoesters and dipolarophiles is considered one of the most powerful and versatile techniques. In this review, we make a detailed overview of the latest developments in this area since 2014 and highlight the recent improvements in the structural scope of dipolarophiles, azomethine ylide precursors, and chiral ligands. [ABSTRACT FROM AUTHOR]

Synthesis, characterization and energetic properties of novel, nitrogen-rich 1-methyl-1,2,4-triazolium N-aryl/N-pyridinyl ylids 3a–m are reported. [ABSTRACT FROM AUTHOR]

A selective one-pot procedure to access 8-, 9-, and 10-membered polyoxacycles bearing ester functions was elaborated. The procedure involved the copper-promoted reactions of cyclic acetals with ethyl 2-diazo-3-oxobutanoate to give the target compounds in yields up to 99%. [ABSTRACT FROM AUTHOR]

The paper describes the synthesis of two regioisomeric 2- amino-3-formyl- and 3-amino-2-formyl-substituted derivatives of tetrahydrobenzo[b]thiophene and their subsequent thermally initiated reactions with secondary amines to give azomethine ylides that undergo intramolecular 1,3-dipolar cycloadditions. In this way, two series of new fused heterocyclic compounds with three stereogenic centers were prepared. The compounds were identified and their structures were determined. [ABSTRACT FROM AUTHOR]

A general method for the formation of alkyl difluoromethylethers under mild reaction conditions and with good functional-group tolerance was developed. The development of the method was based on the invention of a stable, electrophilic, difluoromethylating reagent, difluoromethyl-(4-nitrophenyl)-bis(carbomethoxy) methylide sulfonium ylide, which was synthesized by reaction of the easily available 4-nitrophenyl (difluoromethyl)thioether and dimethyl diazomalonate in the presence of a rhodium catalyst. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the reactions of the dipolarophile compounds, 5-(arylmethylidene)-2,4,6-pyrimidine-2,4,6(1H,3H,5H)-triones, with p-phenacyl- and p-acetonylisoquinolinium bromides which are precursors of azomethine ylides. Topics discussed include the generation of active azomethine ylides as a result of the treatment of N-onion salts with sodium hydroxide, the reactions of the reagents, and the molecular structure of the compounds.

The total synthesis of (+)-tanikolide was accomplished by a traceless stereoinduction method using the key steps of a Rh(II)-catalyzed oxonium ylide formation– [2,3]-sigmatropic rearrangement and an N-heterocyclic carbene-catalyzed ring-expansion lactonization of tetrahydrofurfural. This synthetic route is applicable to the divergent synthesis of tanikolide analogues. [ABSTRACT FROM AUTHOR]

2,2-Dimethyl-5-(triphenylphosphoranylidene)acetyl-1,3-dioxan-4,6-dione (3) is a new activated β-ketoacyl equivalent, readily prepared in quantitative yield by reaction of Meldrum’s acid with the stable ylide Ph 3 PCCO. Its reaction with α-amino esters affords the corresponding N -(β-ketoacyl)amino ester ylides which, when treated with aldehydes and KO t Bu, undergo a simultaneous Wittig olefination cum Dieckmann cyclisation to yield the respective 3-enoyltetramic acids. [ABSTRACT FROM AUTHOR]

A seriesof chiral N,O-ligands derived from a1,2-dihydroimidazo[1,2-a]quinolonemotif have been evaluated for the asymmetric 1,3-dipolar cycloadditionof azomethine ylides with a novel dipolarophile β-phthalimidonitroethene.A newly designed DHIPOH ligand 7cbearing 1-methyl and4-iodo substituents was found to have significant “synergisticsteric effects” and consequently afforded the corresponding4-nitro-3-aminopyrrolidines with excellent diastereo- (dr upto 98:2) and enantio selectivities (ee up to 99%). Subsequent RaneyNi-catalyzed reduction and deprotection of phthalyl led to the structurallyand biologically important 3,4-diaminopyrrolidines in a straightforwardand efficient pathway. [ABSTRACT FROM AUTHOR]

It was recently found that 1-sulfonyl-1,2,3-triazole can act as a 1,3-dipole in the presence of rhodium(II), leading to emergence of diverse rhodium(II)-catalyzed [3+n] cycloaddition reactions using 1-sulfonyl- 1,2,3-triazole. Herein, we highlight development of another dipole, azomethine ylide, which was prepared from 1-sulfonyl-1,2,3-triazole with amide and pyridine derivatives, respectively. Notably, the rhodium(II)-catalyzed reaction of 1-sulfonyl-1,2,3-triazole with pyridines resulted in generation of uniquely isolable azomethine ylide. This azomethine ylide is the first example of an isolable 1,5-dipole that could be cyclized with 2p-dipolarophiles. The new 1,5-dipole provides an avenue for the development of new organic syntheses. 1 Introduction 2 Reactions of 1-Sulfonyl-1,2,3-triazole with Aldehyde 3 1-Sulfonyl-1,2,3-triazole as a Precursor of Azomethine Ylide 4 Generation of Free Azomethine Ylide 5 Outlook [ABSTRACT FROM AUTHOR]

Herein, we describe the synthesis and reactivity of enamines derived from ylidenemalononitriles and ylidenecyanoacetates. The enamine scope was expanded by (1) increasing yields of aldehyde-derived ylidenemalononitriles, (2) incorporating silyl functionalities, and (3) using other amide acetals to expand the substitution patterns of pyridines resulting from enamine cyclization. In addition, methods to produce α-pyrones and polysubstituted pyridines from both ylidenemalononitriles and ylidenecyanoacetates are described. [ABSTRACT FROM AUTHOR]

Nickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons-Smith conditions. [ABSTRACT FROM AUTHOR]

α-Diazo-β-dicarbonyl compounds were chlorinated using (dichloro)iodobenzene and an activating catalyst. A broad range of reaction rates was observed, which paralleled the relative stability/nucleophilicity of the diazo compounds. Acyclic diazocarbonyls reacted faster than cyclics, and β-diketones were much faster to react than β-keto esters or β-diesters. Lewis acid activation was used for the first time, allowing us to overcome instances of poor chemoselectivity. Though the yields ranged from low to good, this chlorination reaction has again proven a mild and effective halogenation strategy. [ABSTRACT FROM AUTHOR]

Dihetaryl thioketones react with thiocarbonyl ylides to give 1,3-dithiolanes in high yields. No competitive side reactions of the thiocarbonyl ylides were observed, evidencing the 'superdipolarophilic' character of this less-known group of thioketones. Depending on the type of substituents present in both the thiocarbonyl ylide and the thioketone, formal [3+2] cycloadditions occur with complete regioselectivity or with formation of a mixture of both regioisomers. Regioselective formation of the sterically more crowded 1,3-dithiolanes is explained via a mechanism involving stabilized 1,5-biradicals. In systems with less-efficient radical stabilization, e.g., in the case of adamantanethione S-methanide, substantial violation of the regioselectivity was observed as a result of steric hindrance. [ABSTRACT FROM AUTHOR]

A S-O bond insertion reaction of sulfoxides with arynes is reported. This reaction represents a rare instance of semipolar single bond insertion in aryne chemistry. The study of mechanism indicates that a sulfur ylide triggered by aryne is the key intermediate, which further transfers its methylene group to carbonyl compounds to give epoxides and thioethers through a sequential process. [ABSTRACT FROM AUTHOR]

The reactions of α-keto stabilized sulfonium ylide (Me)2SCHC(O)C6H4‒m‒NO2(Y1) with HgX2[X˭Cl (1), Br (2) and I (3)] in equimolar ratios and CdCl2.H2O (4) in 1:2 molar ratio using methanol as a solvent lead to binuclear Hg(II) complexes and a polymeric Cd(II) organic–inorganic hybrid. Furthermore, from the reaction of sulfonium ylides (Y1), (Me)2SCHC(O)C6H4‒p‒NO2(Y2), and (Me)2SCHC(O)C6H4‒p‒OMe (Y3) with AgTfO in 2: 1 molar ratio using dichloromethane as a solvent, [Ag(Yn)2]TfO [n = 1 (5), n = 2 (6), n = 3 (7)] complexes were obtained. Single crystal X-ray diffraction analysis reveals the presence of linear structure for5. Characterization of the obtained compounds was also performed by elemental analysis, IR,1H-NMR, and13C-NMR. [ABSTRACT FROM PUBLISHER]

Redox-neutralmethods for the functionalization of amine α-C–Hbonds are inherently efficient because they avoid external oxidantsand reductants and often do not generate unwanted byproducts. However,most of the current methods for amine α-C–H bond functionalizationare oxidative in nature. While the most efficient variants utilizeatmospheric oxygen as the terminal oxidant, many such transformationsrequire the use of expensive or toxic oxidants, often coupled withthe need for transition metal catalysts. [ABSTRACT FROM AUTHOR]

The reactivitiy of tetrakis(trifluoromethyl)cyclopentadienone towards different C-based Lewis bases, such as N-heterocyclic carbenes (NHC), ylides and isonitriles, are reported. While sterically not hindered carbenes were found to yield kinetic adducts by regiospecific nucleophilic attack at the position adjacent to the carbonyl group of the ketone, bulkier nucleophiles afforded the thermodynamically more stable O-bridged zwitterions. Interestingly, isonitriles were found to dimerize and trimerize under the same reaction conditions, forming bicyclic products that evolve differently depending on the nature of the substituents. [ABSTRACT FROM AUTHOR]

The reaction of the stabilized phosphonium ylides 2a, 2b with indolinones 1a, 1b and naphthofuranone 13 afforded the corresponding propylidene and ethylidene derivatives 4a, 4b, 4c, 4d and 14a, 14b. On the other hand, the active phosphacumulenes 5a, 5b react with compounds 4a, 4b, 4c, 4d by [4 + 2]-cycloaddition to give the stable phosphanylidene indole pyranones 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h. Although compounds 14a, 14b afforded the naphthofuropyrans 16a, 16b, 16c, 16d and triphenylphosphane. Moreover, the phosphallene ylide 7 react with compounds 4a, 4b, 4c, 4d and 14a, 14b to give phosphanylidenecyclobuteneindoline 9a, 9b, 9c, 9d and naphthalenones 18a, 18b, respectively. In addition, the naphthofuropyridazine 21 was obtained from the reaction of the hydrazone 19 and the phosphacumulene 5a. The antitumor activity of some of the new compounds was evaluated, in vitro, against colon and hepatocellular carcinoma cell lines. They showed values closed to that recorded by the reference drug Doxorubicin. [ABSTRACT FROM AUTHOR]

The chiral RhI-diene-catalyzed asymmetric three-component reaction of aryldiazoacetates, aromatic amines, and β-nitroacrylates was achieved to obtain γ-nitro-α-amino-succinates in good yields and with high diastereo- and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of RhI-associated ammonium ylides by nitroacrylates. This new transformation represents the first example of RhI-carbene-induced ylide transformation. [ABSTRACT FROM AUTHOR]

The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodium tert-butyl carbonate, and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity up to >95:5, E/ Z. [ABSTRACT FROM AUTHOR]

Indol-2-yl-imidazolium salts were deprotonated at N1 of the indole ring to give ylides. Their tautomeric N -heterocyclic carbenes (NHCs) were trapped by sulfur to give imidazole-2-thiones. Treatment of the ylides with triethylborane resulted in the formation of zwitterionic borane adducts. An analogous sequence of reactions was performed with 8-azaindol-2-yl-imidazolium salts, which served as precursor to prepare first representatives of a new heterocyclic ring system on reaction of their NHC-tautomers with triethylborane. Similarly, an indol-2-yl-1,2,4-triazolium salt was examined with respect to ylide–NHC tautomerism and trapping reactions. A nucleophilic ring transformation of indol-3-amine with a 1,3,4-oxadiazolium salt gave an indol-3-yl-triazolium salt, which was converted into a triazolethione by trapping of the tautomeric N -heterocyclic carbene of its ylide. [ABSTRACT FROM AUTHOR]

The reactions of trivalent phosphorus esters, including trialkyl phosphites, dialkyl phosphonites, and alkyl phosphinites, with 3-halo- and 3,4-dihalo-furan-2,5-diones has been shown to lead to the formation of novel phosphorus ylides possessing additional phosphoryl-containing groups. For the reaction of 3,4-dihalo-furan-2,5-diones with trialkyl phosphites, the products are trialkoxyphosphonium ylides containing an adjacent geminal bisphosphonate unit. These can be used to provide a convenient route to novel 2,3,3-tris(dialkoxyphosphoryl)-substituted propionate esters which can be hydrolyzed to give the corresponding novel trisphosphonic monocarboxylic acid. [ABSTRACT FROM PUBLISHER]

This article presents a study on ring-opening reactions of epoxides with ylides 2 derived from unsaturated carbonyl compounds through the phosphoniosilylation reaction. It discusses the participation of the solvent THF in the ring-opening process of epoxides, and the suitability of THP as a solvent for the phosphoniosilylation reaction of enones with triphenylphosphine.

Rather than lead to the usual deoxygenation pathway, metal carbenes derived from α-diazo-β-ketoesters undergo three-atom insertions into epoxides using a combination of 1,10-phenanthroline and [CpRu(CH3CN)3][BArF] as the catalyst. Original 1,4-dioxene motifs are obtained as single regio- and stereoisomers. A perfect syn stereochemistry (retention, e.r. up to 97:3) is observed for the ring opening, which behaves as an SN1-like transformation. [ABSTRACT FROM AUTHOR]

A full theoretical study of the reaction between a novel type of ylide, i.e. nitrone ylides, and alkenes has been carried out. Both concerted and polar stepwise mechanisms have been considered. Only the zwitterionic mechanism predicts correctly the experimentally observed adducts. Depending on the level of theory, the mechanism moves from concerted to polar stepwise, as demonstrated by the corresponding IRC analyses. The regio- and stereoselectivity of the reaction is well explained for both mono- and disubstituted alkenes. In the case of methyl acrylate a pathway leading to the two diastereoisomers obtained experimentally is predicted. For methyl fumarate a stereospecific mechanism is predicted as a consequence of a ... interaction present in a Li-tricoordinated transition structure. The stereospecificity in the reaction with methyl maleate comes from a less hindered coordination around the lithium atom. Calculations with B3LYP and M06-2X functionals indicate that only the latter provides energy values in good agreement with experimental findings. [ABSTRACT FROM AUTHOR]

Convenient routes for the synthesis of optically active methyl, phenyl, and dimonoterpenyl sulfides derived from carane,p-menthane, pinane, and bornane were developed. Methyl and dimonoterpenyl sulfides have been obtained by the reaction of the corresponding monoterpene thiolates with methyl iodide or monoterpene tosylates. The reactions of monoterpene tosylates with sodium benzenethiolate gave the corresponding phenyl monoterpenyl sulfides. These sulfides were used for the sulfur ylide-mediated reaction to yield epoxides. Good diastereoselectivities up to 99:1 and low to moderate enantioselectivities were observed for the enantioselective synthesis of chiral epoxides. [ABSTRACT FROM PUBLISHER]

Multicomponent reactions (MCRs) are one-pot processes in which three or more starting materials form a product that incorporates the structural features of each reagent. These reactions date back to the mid-19th century, when Strecker first prepared α-aminonitriles through the condensation of aldehydes with ammonia and hydrogen cyanide. In addition to affording products with structural complexity and diversity, MCRs offer the advantages of simplicity, synthetic efficiency, synthetic convergence, and atom economy. Therefore, they have played an important role in modern synthetic organic chemistry and drug-discovery research. [ABSTRACT FROM AUTHOR]

Abstract: An expedient one-pot four component ultrasonic assisted synthesis of novel ferrocene grafted spiro-pyrrolidine heterocycles via [3 + 2]-cycloaddition of azomethine ylides is described. The protocol provides a mild reaction conditions, high yield of product in short reaction time, high regioselectivity, operational simplicity and applicable to a wide variety of ferrocene derived dipolarophiles for the efficient synthesis of ferrocene appended heterocycles. The structures of cycloadducts were confirmed by spectroscopic analysis. X-ray analysis of the products adds conclusive support to the proposed structure. [Copyright &y& Elsevier]

Several abstract related to chemistry are presented which include sulfoxonium ylides, studies of reversible conjugate additions, and domino reaction.

The interconversion between difluoromethylene ylide and difluorocarbene is described. The difluoromethylene ylide precursor, Ph3P+CF2CO2−, could be turned into an efficient difluorocarbene reagent, whereas the classical difluorocarbene reagents, HCF2Cl and FSO2CF2CO2TMS, could generate highly reactive difluoromethylene ylide. Thus the Wittig difluoro-olefination and difluorocyclopropanation could be selectively realized by using the same reagent. In addition, the ylides obtained from different carbene sources showed different reactivity in Wittig reactions. [ABSTRACT FROM AUTHOR]

Keen to donate: A stable and isolable silene with two π‐donating groups on the silicon center has been synthesized. This silicon‐substituted silene shows totally different π‐substituent effects compared to those of related carbon‐substituted silenes, and it presents intrinsic silene properties with an enhanced electron‐donating character, making it an excellent ligand for transition metals. [ABSTRACT FROM AUTHOR]

A recent report suggests that the reaction of dimethylsulfoxonium methylide with esters does not produce a chain-extended sulfur ylide as previously reported, but rather affords the corresponding carboxylate salt. We have investigated this assertion by using a combination of ab initio molecular orbital calculations, spiking studies, and isotopic labeling. The formation of carboxylate is unambiguously demonstrated to arise through hydrolysis involving adventitious water, principally derived from moisture in commercial trimethylsulfoxonium chloride. Careful vacuum drying of this reagent diminishes the competing hydrolytic pathway resulting in higher yields for the chain-extension reaction than previously reported. [ABSTRACT FROM AUTHOR]

Abstract: The Rh2(OAc)4-catalyzed reaction of 2H-azirine-2-carbaldehydes with dimethyl diazomalonate proceeds via azirinium ylide formation, isomerization to 2-azabuta-1,3-dienes followed by 1,6-π-electrocyclization to give 2H-1,3-oxazines. According to DFT-calculations ring opening of azirinium ylides should occur stereoselectively to give 2-azadienes with the C C bond exclusively in the Z configuration. Changing a formyl group for an acetyl group in the azirine leads to a lowering of stereoselectivity and the formation of azadienes with an E configuration of the C C bond was observed. The reaction of 2-acyl-2-diazoacetates with 2H-azirine-2-carbaldehydes proceeds similarly, but the 2-acetyl-substituted 2H-1,3-oxazines formed are unstable under chromatographic purification and rearrange easily into pyrrole derivatives. [Copyright &y& Elsevier]

The reaction of 5(4H)-pyrazolone with phosphorus ylides afforded new triphenylphosphanylidene alkanone derivatives. Moreover, its benzylidene derivative reacted with Wittig–Horner reagents to give the corresponding dialkoxyphosphoryl, alkyl phosphonate, and heterocyclic products. Treatment of pyrazole-4-carbaldehyde with Wittig–Horner reagents and trialkyl phosphites gave the respective alkyl phosphonate adducts. Mechanisms accounting for the formation of the new products are discussed. The biological activity of some of the newly synthesized compounds was also examined. [ABSTRACT FROM AUTHOR]