The novel ylides (II) and (III) have been obtained treatment of perfluoro-1-azacyclohexene and perfluoro-2-azapropene, respectively, with -iminopyridinium ylide (I) generated from -aminopyridinium iodide and anhydrous potassium carbonate in methylene chloride. A mixture of the -triazolo[1,5-]pyridine (IV) and a compound thought to be its dihydro-analogue (V) were isolated following attack on perfluoroacetonitrile by the parent ylide (I); the former product was also prepared by heating 1,2-diamino-pyridinium iodide with trifluoroacetic anhydride. 相似文献
Whereas triethyl phosphite readily reacts with benzoyl chloride to yield the Michaelis-Arbusov product, diethyl benzoyl phosphonate, 1-methyl-4-phospha-3,5,8-trioxabi)cyclo[2.2.2]octane, , is essentially unreactive, even at a higher temperature. The bicyclic phosphite also reacts slower than the triethyl phosphite In an oxidation with t-butyl hydroperoxide. These results are interpreted in terms of the stereoelectronic effect. 相似文献
The title pyridinium salts and pyridinium ylide-platinum(II) complexes have been reduced through a one-electron process at more positive potentials by 0.3 0.6 V than the corresponding ylides. Both the reduced pyridinium salts and Pt(II)-ylide complexes reacted with dioxygen, followed by elimination of the N-methylene and ylide protons to form pyridinium ylides and Pt(II)-pyridinium ylide complexes containing the three-coordinate ylide carbon atom, respectively. 相似文献
Hydrolysis of difluoromethylene phosphonate esters quantitatively yields difluoromethylene phosphonic acid as a dihydrate. drying leads to either the monohydrate or the anhydrous acid. Titration of either the free acid or its disodium salt and computer fit of the data gives all four pKas. The disodium salt and the free acid are thermally stable, and the disodium salt is extremely stable even to strong base. 相似文献
A novel heterocyclic sulfur ylide, 2-t-butyl-3-methyl-1-phenylbenzothiazolinium ylide () was generated as an intermediate in the reaction of 2-t-butyl-3-(nethy1benzothiazoline () with benzyne. The S-ylide underwent a novel intermolecular [1,2] shift to give 2-t-butyl-3-methyl-2-phenylbenzothiazoline (). 相似文献
Keto-stabilized sulphonium ylides displace styrene and benzonitrile from their adducts with PdCl2 to give stable ylidePdCl2 complexes. Evidence is given for epimeric equilibrium between trans square-planar structures of these new complexes in solution.A ylidePdI2 complex, obtained from dimethylsulphonium methylide, is also described. 相似文献
-cyclobutene forms a stable ylide with -tributylarsine. In contrast to the halogen cleavage of the analogous phosphonium ylide, which gives 1,1-dihaloalkanes, the arsonium ylide reacts with bromine and iodine to give the 1-halo--cyclobutenes. 相似文献
Tetrakis(trifluoromethyl)Dewar thiophene () is found to be a good dipolarophile and dienophile. Therefore, reacts with any kind of azides to give 1,3-dipolar cycloadducts, which are transformed to tetrakis(trifluoromethyl)Dewar pyrroles (), compounds of a new cyclic ring system. Further, reacts with cyclic or acyclic dienes to give Diels-Alder adducts. The adduct () of with butadiene was transformed to tetrakis(trifluoromethyl)cyclooctatetraene () by desulfurization, bromination and dehydrobromination, stepwise. Valence-bond isomerisation of will be presented.相似文献
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. 相似文献
Three bench-stable difluoromethylene phosphonate hydrazones were prepared from simple diethyl(difluoromethyl)phosphonate within two steps in good yields. The [3 + 2] cycloaddition reaction of these diazo precursors with aryl diazonium salts has been accomplished under metal-free conditions with exclusive regioselectivity. This transformation provides practical access to a broad panel of 2-aryl-2 H-tetrazol-5-yl difluoromethylene phosphonates, including the corresponding derivatives of amino acid... 相似文献
The facile synthesis of 3-methylene-2,3-dihydro-5H-thiazolo-[3,2-c]pyrimidin-5-ones () has been performed by the catalytic action of a Pd(II) salt on 4-propargylthiopyrimidin-2(1H)-ones ().Similar Pd(II)-catalyzed cyclization of 3-propargylthio-1,2,4-triazin-5(2H)-ones () gives 6-methylene-6,7-dihydro-4H-thiazolo[2,3-c](1,2,4]-triazin-4-ones () as a main product. 3-Methylene-2,3-dihydro-7H-thiazolo[3,2-b][1,2,4]triazin-7-ones (), the regioisomers of are provided by a base-catalyzed cyclization of [ulbar 10]. 相似文献
The synthesis of cycloimmonium salts of the type , and the corresponding cycloimmonium ylides , are reported. In the reaction with diazonium salts , the pyridinium monosubstituted carbanion ylides , give the pyridinium disubstituted carbanion ylides – . These are new types of isolable stable ylides. The synthesis involves the formation “in situ” of ylides , which are bonded by their nucleophile ylide carbon atom to the nitrogen atom in diazonium salts. The intermediat formation of cycloimmonium salts – must be accepted. The structures of all compounds presented in this paper have been established by using elementary analysis, IR and 1H-RMN spectra. 相似文献
The application of the Michaelis-Becker variation to the preparation of unsymmetrical -methylene -phosphonates gives a mixture of both symmetrical and unsymmetrical -phosphonates. The reaction is best explained by dissociation of the intermediate -methylene phosphonate ylide and carbene scrambling among the potential dialkyl phosphite anions. 相似文献
Reactions of alloxan (all) with [PtL(PPh3)2] (L′= -stilbene, L″ diphenylacetylene) afford the side-bonded ketone complex [Pt(all)(PPh3)2] which may also be obtained from the hydrate of alloxan and [PtL′(Pph3)2]. Similarly diethyl oxomalonate (dio) and [Pt(PPh3)4] afford a side-bonded ketone complex [Pt(dio)(PPh3)2]. Reaction of isatin with [Pt(PPh34] gives -[PtH{}(PPh3)2] and benzoyl cyanide and [PtL′(PPh3)2] give -[Pt(CN)(COPh3)2] and -[Pt(CN)2(PPh2)2]. 相似文献
The reaction of β-fluoro vinamidinium salt 1 with Horner-Wadsworth-Emmons reagents (HWE) such as diethyl(ethoxycarbonyl)methylphosphonate (2a), diethyl(methoxycarbonyl)methylphosphonate (2b), diethyl-2-oxopropylphosphonate (2c), diethyl benzylphosphonate (2d), tetraethyl methylenediphosphonate (2e) and diethyl cyanomethylphosphonate (2f) under basic conditions gave the fluorinated 1,3-butadienylphosphonates 3 in moderate to good yields. The phosphonates 3 could be hydrolyzed with a 10% HCl aqueous solution to afford the corresponding γ-(diethylphosphono)-α-fluoro-α,β-unsaturated aldehydes 7 in good yields. The treatment of the phosphonate 3c with an NH3 aqueous solution at 70 °C produced the pyridine derivative 8 in 60% yield. 相似文献