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The stereoselective cyclopropanation of olefins with “boron ylide” is disclosed for the first time, providing a modular strategy for the synthesis of stereospecific diboryl‐functionalized cyclopropanes. The chiral gem‐diborylcyclopropanes are synthesized with excellent enantioselectivity with the aid of a chiral auxiliary. Based on the powerful transformable ability of boryl group, those challenging multi‐quaternary carbon centers in cyclopropane units have been facilely constructed with excellent stereoselectivity. Control experiments indicate that the boryl groups are necessary for both chemoselectivity and stereoselectivity control. [ABSTRACT FROM AUTHOR]

Classical organic chemical reactions are essential for modern synthetic chemistry and offer valuable insights for chemical biology research. The pioneering bioorthogonal chemistry, based on the Staudinger reaction, is a prime example. However, the biocompatibility of classic "name" reactions like the Wittig reaction is still not fully explored. This versatile reaction efficiently converts carbonyl groups into olefins using phosphorus ylides, making it valuable in synthetic chemistry. Despite being in the early stages of development, the Wittig reaction and its reagents have various applications in peptide, protein, DNA, and RNA research. However, they have limitations such as low activity and efficiency, requiring organic solvents. Future directions may include developing Wittig reagents with improved biostability, simplifying the method, and creating multi‐labeling methods. Improving light‐activated Wittig reactions and interdisciplinary integration can further advance bioorthogonal chemistry. As technology advances, the Wittig reaction is poised to make greater contributions to molecular biology, cell biology, and biochemical modification research. [ABSTRACT FROM AUTHOR]

Mesoionische Polarisation ermöglicht den Zugang zu elektronenreichen Olefinen, die als Organokatalysatoren, Liganden oder Nucleophile Anwendung finden. Wir berichten hier über die Synthese und Charakterisierung einer Reihe von 3‐Methylpyridinium‐abgeleiteten mesoionischen Olefinen (py‐mNHOs). Wir verwendeten ein mit DFT‐Rechnungen unterstütztes Designkonzept, das zeigte, dass Arylgruppen an den 1‐, 2‐, 4‐ und 6‐Positionen des heterocyclischen Kerns die kinetische Stabilisierung der neuartigen mesoionischen Verbindungen ermöglicht. Die elektronischen Tolman‐Parameter zeigen, dass py‐mNHOs bemerkenswert starke σ‐Donor‐Liganden für Übergangsmetalle und Hauptgruppen‐Lewis‐Säuren sind. Außerdem gehören sie zu den stärksten Nucleophilen auf der Mayr‐Reaktivitätsskala. Bei Reaktionen von py‐mNHOs mit elektronenarmen π‐Systemen wurde experimentell ein sukzessiver Übergang von der Bildung zwitterionischer Addukte über schrittweise zu konzertierten 1,3‐dipolaren Cycloadditionen beobachtet und durch quantenchemische Rechnungen analysiert. [ABSTRACT FROM AUTHOR]

Aprotic heterocyclic anions (AHAs) can abstract hydrogen atoms from the methylene groups of the trialkylsulfonium and tetraalkylphosphonium cation. The resulting trialkylsulfonium and tetraalkylphosphonium ylides readily capture CO2 and produce unusual carboxylated zwitterions, in which the distances between the poles, S(P) and O, are 0.274–0.290 nm. The zwitterions are strongly intermolecularly stabilized thanks to the electrostatic attractions between +1.6e(+0.9e) and −0.7e charges. Herein, we report drastic polarity alterations between the states of ionic liquids, ylides, and zwitterions through electronic properties, evolutions of geometries, and interatomic charge transfers. The analysis of the unusual intermolecular attractions was performed in the framework of natural bond orbitals. We propose that a biphasic or triphasic system can be useful to boost the reactions by accounting for the polarities of the intermediates and products. The practical value of the reaction is an enhancement in CO2 chemisorption.

Zwitterionic polymers are widely employed hydrophilic building blocks for antifouling coatings with numerous applications across a wide range of fields, including but not limited to biomedical science, drug delivery and nanotechnology. Zwitterionic polymers are considered as an attractive alternative to polyethylene glycol because of their biocompatibility and effectiveness to prevent formation of biofilms. To this end, zwitterionic polymers are classified in two categories, namely polybetaines and polyampholytes. Yet, despite a fundamental interest to drive the development of new antifouling materials, the chemical composition of zwitterionic polymer remains severely limited. Here, we show that poly(sulfur ylides) that belong to the largely overlooked class of poly(ylides), effectively prevent the formation of biofilms from pathogenic bacteria. While surface energy analysis reveals strong hydrogen‐bond acceptor capabilities of poly(sulfur ylide), membrane damage of pathogenic bacteria induced by poly(sulfur ylides) indicates toxicity towards bacteria while not affecting eucaryotic cells. Such synergistic effect of poly(sulfur ylides) offers distinct advantages over polyethylene glycol when designing new antifouling materials. We expect that our findings will pave the way for the development of a range of ylide‐based materials with antifouling properties that have yet to be explored, opening up new directions at the interface of chemistry, biology, and material science. [ABSTRACT FROM AUTHOR]

Kürzlich berichteten wir, dass α‐metallierte Ylide einen Phosphan‐CO‐Ligandenaustausch eingehen und darüber Zugang zu isolierbaren Ketenylanion liefern. Systematische Studien an Tosyl‐substituierten Yldiiden der Form R3P=C(M)Ts (M=Li, Na, K) zeigen nun, dass die Carbonylierung auch zu einer konkurrierenden Metallsalzeliminierung (MTs) führen kann. Diese Nebenreaktion kann durch die Wahl des Phosphans, des Metallkations, des Lösungsmittels und der Zugabe geeigneter Coliganden kontrolliert werden, was die selektive Isolierung des Ketenylanions [Ts−CCO]M (2‐M) ermöglicht. Die Komplexierung von 2‐Na durch Kronenethern oder Kryptanden ermöglichte zudem die Strukturaufklärung des ersten freien Ketenylanions [Ts−CCO], welches eine annähernd lineare S−C−O‐Einheit aufweist, was auf einen höheren Anteil der Ynolat‐Grenzstruktur hindeutet. DFT‐Studien zeigen jedoch eine hohe negative Ladung am Ketenylkohlenstoff, was sich in der selektiven Reaktivität am C1‐Atom widerspiegelt. Die vorgestellten Ergebnisse liefern wichtige Informationen über die Selektivitätskontrolle der Carbonylierung von α‐metallierten Ylide, was für künftige Anwendungen unabdingbar ist. [ABSTRACT FROM AUTHOR]

The present work focuses on the reactivity of S,S-bis-ylide 2, which presents a strong nucleophilic character, as evidenced by reactions with methyl iodide and CO2, affording C-methylated salts 3 and betaine 4, respectively. The derivatization of betaine 4 affords the corresponding ester derivative 6, which is fully characterized by using NMR spectroscopy and X-ray diffraction analysis. Furthermore, an original reaction with phosphenium ions leads to the formation of a transient push–pull phosphino(sulfonio)carbene 8, which rearranges to give stabilized sulfonium ylide derivative 7. [ABSTRACT FROM AUTHOR]

C(sp3)−C(sp2) cross‐coupling reactions are an indispensable tool for organic synthesis. In these reactions transition metals have been extensively employed to promote the formation of valuable carbon‐carbon bonds. Herein, we report our recent discovery of a designer thioether as a highly active organocatalyst for reactions between an allyl bromide and an arylboronic acid. The cross‐coupling event occurred readily under mild condition in the presence of a weak inorganic base. Preliminary mechanistic studies suggested a sulfonium ylide mechanism. [ABSTRACT FROM AUTHOR]

The stereoselective cyclopropanation of olefins with "boron ylide" is disclosed for the first time, providing a modular strategy for the synthesis of stereospecific diboryl-functionalized cyclopropanes. The chiral gem-diborylcyclopropanes are synthesized with excellent enantioselectivity with the aid of a chiral auxiliary. Based on the powerful transformable ability of boryl group, those challenging multi-quaternary carbon centers in cyclopropane units have been facilely constructed with excellent stereoselectivity. Control experiments indicate that the boryl groups are necessary for both chemoselectivity and stereoselectivity control., (© 2024 Wiley-VCH GmbH.)

The present work focuses on the reactivity of S,S-bis-ylide 2, which presents a strong nucleophilic character, as evidenced by reactions with methyl iodide and CO2, affording C-methylated salts 3 and betaine 4, respectively. The derivatization of betaine 4 affords the corresponding ester derivative 6, which is fully characterized by using NMR spectroscopy and X-ray diffraction analysis. Furthermore, an original reaction with phosphenium ions leads to the formation of a transient push–pull phosphino(sulfonio)carbene 8, which rearranges to give stabilized sulfonium ylide derivative 7.

Primary acyl‐phosphines are scarce in the literature. Here we show that the reaction of Ph3GePCO with the ylide Ph3PCH2 proceeds to give the species Ph3PCHC(O)PH(GePh3) 1. Deprotonation of 1 with Na[N(SiMe3)2] generates the salt [Na(THF)2][Ph3PCHC(O)P(GePh3)] 2 which provides subsequent access to the bis‐germanylated acylphosphine, Ph3PCHC(O)P(GePh3)23. Alternatively, treatment of 1 with HCl in dioxane affords the primary acylphosphine Ph3PCHC(O)PH24. Compound 4 is a rare example of an air stable primary acyl‐phosphines and the first devoid of a stabilizing heteroatom adjacent to the carbonyl fragment. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A simple one pot synthesis of polysubstituted pyrroles via ketenimine formation/Ag(I)‐catalyzed alkyne cycloisomerisation has been developed. The easily accessible phosphorane ylide derivatives reacted with isocyanates, producing highly active ketenimines that were then treated with amines, which afforded substituted pyrroles by a 5‐exo‐dig cyclization/isomerization in the presence of a Ag(I) catalyst in good overall yields. [ABSTRACT FROM AUTHOR]

The reaction of the bicyclic polyfunctional electrophilic system – 1-ethoxy-5-methyl-3,8-diphenyl-1 H -pyrano[3,4- c ]pyran-7-ium perchlorate with heterocyclic and aromatic acid hydrazides leads to the corresponding N-aminopyridinium ylides in one-pot. The reaction conditions have been optimized and a mechanism for the formation of the ylides has been proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

The title compound, [Co(C5H5)(C10H9N2)]PF6, was synthesized from deprotonated 1-aminopyridinium iodide, followed by microwave-assisted nucleophilic aromatic substitution of iodo-cobaltocenium iodide. After anion exchange with potassium hexafluoridophosphate, the title compound crystallizes as orange prisms in the space group Pc. This very stable pyridine nitrene adduct is the first example of a cobaltocenium derivative, formally containing a nitrene nitrogen species.

The Mes2P‐C≡C‐SiMe3 alkyne reacts with the borane H2B‐Fmes by means of a rare 1,1‐hydroboration reaction to give an unsaturated C2‐bridged frustrated P/B‐H Lewis pair. Most of its reactions are determined by the presence of the B‐H functionality at the FLP function and the activated connecting carbon‐carbon double bond. It reduces carbon monoxide to the formyl stage. With nitriles it reacts in an extraordinary way: it undergoes a reaction sequence that eventually results in the formation of a P‐substituted dihydro‐1,2‐azaborole derivative. Several similar examples were found. In one case a P‐ylide was isolated that was related to an intermediate of the reaction sequence. It subsequently opened in an alternative way to give an alkenyl borane product. [ABSTRACT FROM AUTHOR]

A one-pot synthesis of epoxides from commercially available benzyl alcohols and aldehydes is described. The reaction proceeds through in situ generation of sulfonium salts from benzyl alcohols and their subsequent deprotonation for use in Corey–Chaykovsky epoxidation of aldehydes. The generality of the method is exemplified by the synthesis of 34 epoxides that were made from an array of electronically and sterically varied alcohols and aldehydes.

Summary of main observation and conclusion: Structure‐reactivity study of a family of electrophilic monofluoromethylating reagents based on sulfonium ylide skeleton with different steric hindrance and electron‐withdrawing properties was described. These studies led us to discover two highly reactive reagents 3 with a cyclic malonate backbone and 6 with an electron‐poor 1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione backbone. The high reactivity of reagent 6 allowed to highly selectively access either C‐monofluoromethylated or O‐monofluoromethylated β‐ketoesters in high yields by the use of different bases. In addition, reactions of reagent 3 with a variety of nucleophiles including phenols, carboxylic acids, thiophenols or heteroaryl nucleophiles occurred in full conversion within 10 min at room temperature and the scopes for these reactions were reported in detail. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: Structure‐reactivity study of a family of electrophilic monofluoromethylating reagents based on sulfonium ylide skeleton with different steric hindrance and electron‐withdrawing properties was described. These studies led us to discover two highly reactive reagents 3 with a cyclic malonate backbone and 6 with an electron‐poor 1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione backbone. The high reactivity of reagent 6 allowed to highly selectively access either C‐monofluoromethylated or O‐monofluoromethylated β‐ketoesters in high yields by the use of different bases. In addition, reactions of reagent 3 with a variety of nucleophiles including phenols, carboxylic acids, thiophenols or heteroaryl nucleophiles occurred in full conversion within 10 min at room temperature and the scopes for these reactions were reported in detail. [ABSTRACT FROM AUTHOR]

Treatment of [Ph3EMe][I] with [Na{N(SiMe3)2}] affords the ylides [Ph3E=CH2] (E=As, 1As; P, 1P). For 1As this overcomes prior difficulties in the synthesis of this classical arsonium‐ylide that have historically impeded its wider study. The structure of 1As has now been determined, 45 years after it was first convincingly isolated, and compared to 1P, confirming the long‐proposed hypothesis of increasing pyramidalisation of the ylide‐carbon, highlighting the increasing dominance of E+−C− dipolar resonance form (sp3‐C) over the E=C ene π‐bonded form (sp2‐C), as group 15 is descended. The uranium(IV)–cyclometallate complex [U{N(CH2CH2NSiPri3)2(CH2CH2SiPri2CH(Me)CH2)}] reacts with 1As and 1P by α‐proton abstraction to give [U(TrenTIPS)(CHEPh3)] (TrenTIPS=N(CH2CH2NSiPri3)3; E=As, 2As; P, 2P), where 2As is an unprecedented structurally characterised arsonium‐carbene complex. The short U−C distances and obtuse U‐C‐E angles suggest significant U=C double bond character. A shorter U−C distance is found for 2As than 2P, consistent with increased uranium‐ and reduced pnictonium‐stabilisation of the carbene as group 15 is descended, which is supported by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Three different arsonium salts were prepared by a solvent‐free method from Ph3As and the respective 2‐bromoacetophenones. These salts were deprotonated by NaOH to form keto‐stabilized arsenic ylides. The ylids react with [AuCl(tht)] affording gold(I) complexes containing the C‐bound ylide. The compounds were characterized by NMR spectroscopy, IR spectroscopy, and X‐ray diffraction. [ABSTRACT FROM AUTHOR]

A synergistic rhodium‐ and Brønsted acid‐ catalyzed reaction of quinone imine ketals with diazo compounds to access multi‐substituted anilines is presented here. This reaction takes place through a process involving C−O bond cleavage, modification of the leaving alcoholic fragment, and selective reassembly of the reactive fragments. Moderate enantioselectivities are achieved when a chiral 1,1'‐bi(2‐naphthol)‐based phosphoric acid is used. [ABSTRACT FROM AUTHOR]

We report a new class of stable mesoionic N‐heterocyclic olefins, featuring a highly polarized (strongly ylidic) double bond. The ground‐state structure cannot be described through an uncharged mesomeric Lewis‐structure, thereby structurally distinguishing them from traditional N‐heterocyclic olefins (NHOs). mNHOs can easily be obtained through deprotonation of the corresponding methylated N,N′‐diaryl‐1,2,3‐triazolium and N,N′‐diaryl‐imidazolium salts, respectively. In their reactivity, they represent strong σ‐donor ligands as shown by their coordination complexes of rhodium and boron. Their calculated proton affinities, their experimentally derived basicities (competition experiments), as well as donor abilities (Tolman electronic parameter; TEP) exceed the so far reported class of NHOs. [ABSTRACT FROM AUTHOR]

Due to their remarkable electronic features, recent years have witnessed the emergence of carbones L2C, which consist in two donating L ligands coordinating a central carbon atom bearing two lone pairs. In this context, the phosphine/sulfoxide-supported carbone 4 exhibits a strong nucleophilic character, and here, we describe its ability to coordinate dichlorogermylene. Two original stable coordination complexes were obtained and fully characterized in solution and in the solid state by NMR spectroscopy and X-ray diffraction analysis, respectively. At 60 °C, in the presence of 4, the Ge(II)-complex 5 undergoes a slow isomerization that transforms the bis-ylide ligand into an yldiide.

We have developed a method for the highly diastereo‐ and enantioselective construction of 2,3‐dihydrobenzofurans bearing tetrasubstituted carbon stereocenters by means of annulation reactions between carbenes and 2‐iminyl‐ or 2‐acyl‐substituted phenols through catalysis by readily accessible copper(I)/bisoxazoline catalysts under mild conditions. These reactions feature a unique mechanism in which the copper catalyst serves a dual function: first it reacts with the diazo compound to generate a metal carbene, and second, upon formation of an oxonium ylide, it acts as a Lewis acid to activate the imine or ketone for diastereo‐ and enantioselective cyclization. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective [2,3] Stevens and Sommelet–Hauser rearrangements of α‐diazo pyrazoleamides with sulfides were achieved by utilizing chiral N,N′‐dioxide/nickel(II) complex catalysts. These rearrangements proceeded well under mild reaction conditions, providing rapid and facile access to a series of functionalized 1,6‐dicarbonyls or sulfane‐substituted phenylacetates with high to excellent enantioselectivities. The catalytic system shows excellent stereocontrol, discriminating between the heterotopic lone pairs of sulfur and controlling both the 1,3‐proton transfer and the [2,3]‐σ rearrangement. [ABSTRACT FROM AUTHOR]

Synthesis of functionalized spiro[acenaphthylene‐1,3′‐pyrrolizin]‐2‐ones and spiroindeno[1,2‐b]quinoxaline‐11,3′‐pyrrolizines has been reported by one‐pot condensation of active carbonyl compounds, L‐proline/L‐thioproline and 3‐methyl‐4‐nitro‐5‐styrylisoxazoles in MeOH under reflux. This multicomponent strategy afforded corresponding spiro products in 94–98% yield with high diastereo‐ and regioselectivity. The structure has been further confirmed by X‐ray analysis of single crystal of one of the compounds. The striking feature of this work is avoidance of usage of toxic catalysts for this one‐pot synthesis. [ABSTRACT FROM AUTHOR]

Die Darstellung des ersten stabilen, diylidsubstituierten Stannylens und Germylens Y2E (mit E=Ge, Sn und Y=[PPh3‐C‐SO2Tol]−) wird berichtet. Die Synthese gelingt in einem Schritt durch die einfache Umsetzung des metallierten Ylids YNa mit der entsprechenden Vorstufe ECl2. Y2Ge und Y2Sn weisen eine ungewöhnliche Struktur sowohl im Festkörper als auch in Lösung auf, bei der die drei freien Elektronenpaare der zentralen C‐E‐C‐Einheit coplanar zueinander angeordnet sind. DFT‐Studien zeigen, dass aufgrund der starken anionenstabilisierenden Eigenschaften der Sulfonylgruppen im Ylidrückgrat und deren Koordination an das Metall diese Bindungssituation gegenüber der typischen π‐Donation des Liganden in das freie p‐Orbital des Metalls bevorzugt wird. Die Ausrichtung der drei freien Elektronenpaare führt zu einer deutlichen Erhöhung der HOMO‐Energie und damit der Donorstärke der Tetrylene. Hierdurch werden Y2Ge und Y2Sn zu stärkeren Donoren als ihre diamin‐ oder diarylsubstituierten Analoga und vergleichbar mit cyclischen Alkyl(amino)carbenen. Erste Reaktivitätsstudien bestätigen die hohe Reaktivität von Y2Ge und Y2Sn, welche zum Beispiel intramolekulare C‐H‐Aktivierungen mittels Metall‐Ligand‐Kooperation eingehen. [ABSTRACT FROM AUTHOR]

Abstract The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of typical N -heterocyclic carbenes NHCs, r -NHCs, a -NHCs and MICs have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. Prior to that both structures and 13C chemical shifts were calculated and in case of isolated carbenes the computed δ (13C)/ppm values compared (as a quality criterion for obtained structures) with the experimental ones. The TSNMRS values of the studied carbenes, which are in mesomeric equilibrium with zwitterionic (ylide/betaine/mesoionic) resonance contributors , are employed to qualify and quantify the present electronic structure and if the term carbene is still justified to denote the compounds studied. The results, thus obtained from spatial magnetic properties (TSNMRS), are compared with the geometry of the compounds, the corresponding WIBERG's bond index values, and the 13C chemical shifts especially of the carbene electron-deficient centre. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Ylid‐funktionalisierte Phosphanliganden (YPhos) wurden entwickelt, um den Voraussetzungen einer Buchwald‐Hartwig‐Aminierung bei Raumtemperatur zu genügen. Diese Ligandenklasse kombiniert ein besonders hohes Elektronendonorvermögen, vergleichbar mit dem von NHC‐Liganden, mit hohem sterischem Anspruch ähnlich jenem von Biarylphosphanen. Die aktiven Pd‐Spezies sind dabei über agostische C‐H⋅⋅⋅Pd‐ und nicht über Pd‐Aren‐Wechselwirkungen stabilisiert. Der praktische Vorteil dieser YPhos‐Liganden liegt insbesondere in deren einfacher und skalierbarer Synthese ausgehend von leicht zugänglichen sowie günstigen Startmaterialien. Benchmark‐Untersuchungen zeigten, dass YPhos‐Pd‐Komplexe den üblicherweise verwendeten Phosphanliganden in Aminierungen von Arylchloriden bei Raumtemperatur überlegen sind. Der enorme Nutzen dieses Katalysatorsystems konnte durch die Synthese zahlreicher Arylamine in sehr guten Ausbeuten bei geringer Reaktionszeit aufgezeigt werden. Leicht herstellbar über zwei Stufen ist ein Ylid‐funktionalisiertes Phosphan (YPhos; siehe Struktur) mit herausragender Aktivität in einer Reihe von C‐N‐Kreuzkupplungen bei Raumtemperatur. Die hohe Effizienz lässt sich durch die stark elektronenschiebenden Eigenschaften des Liganden sowie die besondere Architektur, die für eine Stabilisierung der aktiven Pd‐Spezies durch schwache C‐H⋅⋅⋅Pd‐Wechselwirkungen sorgt, erklären. [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. [ABSTRACT FROM AUTHOR]

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Abstract P=CH 2 ylides derived from ortho -alkynylphenylphosphines readily cyclize to give phosphindole derivatives. With a stabilized ylide such as P=CHC(O)Ph, the outcome of the reaction is completely different. The reaction proceeds at high temperature and produces phosphanaphthalenes. Graphical abstract Image 1 Highlights • To the best of our knowledge, this paper describes the first instance where the intramolecular cyclization of an ylide onto a non-activated alkene completely shifts from the formation of a 5-membered to a 6-membered ring according to the nucleophilicity of the ylide. [ABSTRACT FROM AUTHOR]

In this account, our group's efforts towards exploring new substrates as precursors for the Wittig reaction have been discussed. Several new strategies developed by our group for the generation of requisite ylides for the Wittig reaction are highlighted. The idea behind the development of some chemoselective and diversity-oriented strategies are discussed in detail in a progressive manner. These strategies encompass a wide range of substrates that are employed for the synthesis of an array of heterocycles and multifunctional olefins and present a huge scope for their application on an industrial level. [ABSTRACT FROM AUTHOR]

Cycloadditions are powerful processes to synthesize complex polycyclic scaffolds. Herein, we disclose a [4+3]‐cycloaddition between an in situ generated ortho‐quinone methide and an isomünchnone to yield oxa‐bridged oxazocine cores, generating N2 and H2O as the sole by‐products. Using only catalytic amounts of camphorsulfonic acid, it is possible to generate both reactive intermediates in one step, eliminating the need for rhodium catalysts generally employed for isomünchnone formation. Spectroscopic data and X‐ray crystallography indicate the formation of the syn diastereomer, with the main side‐product arising from a hydrate participating in a competing [4+2]‐cycloaddition pathway. [ABSTRACT FROM AUTHOR]

A method for the generation of unprecedented vinyl carbenoids from sulfoxonium ylides has been developed and applied in the synthesis of a diverse array of heterocycles such as indolizines, pyrroles, 3‐pyrrolin‐2‐ones, and furans. The reactions proceed by FeBr2 catalysis under mild reaction conditions with a broad substrate scope. A reaction pathway involving iron carbenoids is proposed based on a series of control experiments and DFT calculations. [ABSTRACT FROM AUTHOR]