Showing papers on "Ylide published in 1975"

Synthesis and reaction of new type i–n ylide, n-tosyliminoiodinane

Abstract: (Diacetoxyiodo)arene reacts with p-toluenesulfonamide in the presence of base to give the new type I–N ylide, N-tosyliminoaryliodinane. In the decomposition of this ylide, the nitrene intermediate is proposed to be formed and react with nucleophiles to afford the imine compounds.

Organogold‐Chemie, XV. Gold(I)‐Verbindungen einfacher Phosphor‐ylide

Abstract: Alkyl(phosphin)gold(I)-Komplexe reagieren rasch und vollstandig mit Phosphor-yliden unter Verdrangung der Phosphine vom Goldatom und Bildung neuartiger, ungewohnlich stabiler Alkylgold-ylid-Komplexe. Prototyp dieser Produkte ist CH3AuCH2P(CH3)3 (1) mit zwei AuC-σ-Bindungen. Auch silylierte Alkylgold-Komplexe (CH3)3SiCH2AuPR3 und silylierte Ylide (CH3)3PCHSi(CH3)3 geben diese Reaktion. (Phosphin)gold(I)-halogenide addieren Phosphor-ylide unter stufenweiser Substitution des Halogens und des Phosphins. Dabei entstehen oniumstabilisierte Alkylgoldsalze der Typen [(CH3)3P CH2 Au P(CH3)3]X und (CH3)3P CH2 Au CH2 P(CH3)3X etc. Organogold Chemistry, XV. Gold(I) Compounds of Simple Phosphorus Ylides Alkyl(phosphine)gold(I) complexes react rapidly and quantitatively with phosphorus ylides with displacement of the phosphine to give novel alkylgold ylide complexes of unusual stability. CH3AuCH2P(CH3)3, with its two AuC σ-bonds, is a prototype of these reaction products. Silylated alkylgold complexes (CH3)3SiCH2AuPR3 and silylated ylides also give this reaction. — (Phosphine)gold(I) halides add phosphorus ylides with stepwise substitution of the halogen and phosphine ligands and formation of onium-stabilized alkylgold salts of the type [(CH3)3P CH2 Au P(CH3)3]X and [(CH3)3P CH2 Au CH2 P(CH3)3]X.

Synthesis of freelingyne, an acetylenic sesquiterpene from Eremophila freelingii

Abstract: The application of the 2-methyl-4-triphenylphosphoranylidenebut-2-en-4-olide (6) in the total synthesis of natural freelingyne (19) and its geometrical isomer (1)[(4Z)- and (4E)-isomers of (6E)-9-(3-furyl)-2,6-dimethylnona-2,4,6-trien-8-yn-4-olide] is described. A coupling reaction between 3-furylcopper (16) and the iodoacetylene (15) provided the (3-furyl)-enyne (17b), hydrolysis of which, followed by oxidation, led to the aldehyde (5). Condensation between the ylide (6) and the aldehyde (5) produced a mixture of isomers of free-lingyne, one of which, assigned the structure (19) from X-ray measurements, was identical with the naturally derived material.

Metal–ylide complexes. Part I. Metallation reactions of N-(1-pyridinio)benzamidate and related compounds with palladium(II), platinum(II), rhodium(III), and iridium(III)

Abstract: The reaction of various ylides of general formula RCO··[graphic omitted] [R = Ph or m- or p-MeC6H4; X = N or CH; Y = pyridine, NMe3, or PPh3(most work has been carried out with PhCO··[graphic omitted]H5C5= L)] with halide salts of palladium(II), platinum(II), rhodium(III), and iridium(III) affords products containing metallated betaines. Spectroscopic data (i.r., 1H, and 13C n.m.r.) show unambiguously that the aryl group R has become metallated in a position ortho to the carbonyl group and also that the ylide is bidentate (L′)via the group X. There is good evidence to indicate that the mechanism of the reaction involves preliminary co-ordination of the ylide followed by intramolecular electrophilic attack by the metal. Palladium tends to give di-µ-halogeno-complexes, [{Pd(L′)Y}2], whereas in the case of platinum it is possible to prepare [PtL′2] which has cis-Pt–C bonds. Rhodium affords ionic complexes, cis-[RhL′2(H2O)2]Z (Z = Cl, Br, I, or BPh4), which with 2,2′-bipyridyl give [RhL′2(bipy)]Cl. Iridium gives a non-ionic derivative, [IrL′2(H2O)Cl],3H2O. Reactions of the complexes with Ph3P or Bun3P give new complexes containing phosphine oxide such as [PdL′{P(O)Ph3}]Cl, [PtL′{P(O)Ph3}Cl], [RhL′2{P(O)-Bun3}Cl], and [IrL′2{P(O)Ph3}Cl]. The Pd–Cl and Pt–Cl bonds are trans to nitrogen when L = PhCO··[graphic omitted]H5C5. Carbon monoxide reacts reversibly with palladium and iridium complexes of PhCO··[graphic omitted]H5C5to give [PdL′(CO)Cl] and [IrL′2(CO)2]Cl. I.r. evidence suggests CO to be cis to the Pd–C bond in the palladium complex and other observations suggest that the mode of formation is not simple.

Studies on Ketene and Its Derivatives. LXVIII. Reaction of Diketene with N-Imino-pyridinium, -quinolinium, and -isoquinolium Ylides

Abstract: 1-Iminopyridinium ylide reacted with diketene to give 1-(N-acetoacetylimino)-pyridinium ylide (VI), which, on treatment with sodium ethoxide, was transformed to 3-acetyl-2-hydroxypyrazolo [1, 5-a] pyridine (XI). On the other hand, reaction of diketene with 1-(N-methylimino) pyridinium ylide afforded directly 3-acetyl-1-methylpyrazolo [1, 5-a] pyridin-2-one (VIII). Reaction of diketene with 1-iminoquinolinium ylide (XIII) and 2-iminoisoquinolinium ylide (XVI) gave rise to 3-acetyl-2-hydroxypyrazolo [1, 5-a] quinoline (XV) and 3-acetyl-2-hydroxypyrazolo [1, 5-a] isoquinoline (XVII), respectively.

Die Reaktionen von Phosphor‐yliden mit Silacyclobutanen, III. Silacyclobutyl‐substituierte Phosphor‐ylide

Abstract: Aus 1-Chlor-1-methylsilacyclobutan (1b) und den sterisch anspruchsvollen Yliden Triisopropylmethylen-, Triathylathyliden- und Trimethyl(trimethylsilylmethylen)phosphoran entstehen, unter Erhaltung des Ringsystems, durch Umylidierung Methylsilacyclobutyl-ylide (2b–d). Am 1,1-Dichlorsilacyclobutan (1c) konnen analog beide Halogenatome durch Ylid-Funktionen ersetzt werden (4a, b). Diese difunktionellen Ylide binden als zweizahnige Liganden Dialkylzink und -cadmium zu spirocyclischen 1:1-Komplexen (7a, b). Aus 1c und (CH3)3PC[Si(CH3)3]2 wird unter Umsilylierung [Bis(1-chlor-1-sila-1-cyclobutyl)methylen]trimethylphosphoran (5) erhalten. The Reactions of Phosphorus Ylides with Silacyclobutanes, III. Silacyclobutyl-substituted Ylides From 1-chloro-1-methylsilacyclobutane (1b) and bulky ylides such as triisopropylmethylene-, triethylethylidene-, and trimethyl(trimethylsilylmethylene)phosphorane, the methylsilacyclobutyl ylides 2b–d are obtained in a transylidation reaction, leaving the ring system intact. Similarly, the two chlorine atoms in 1,1-dichlorosilacyclobutane (1c) can be replaced by ylidic functions (4a, b). These difunctional ylides add to dialkylzinc and -cadmium with formation of spirocyclic 1:1 complexes (7a, b). A transsilylation reaction between 1c and (CH3)3PC[Si(CH3)3]2 yields [bis(1-chloro-1-sila-1-cyclobutyl)methylene]trimethylphosphorane (5).

The mechanism of the Stevens rearrangement

Abstract: The influence of solvent viscosity and reaction temperature upon the stereoselectivity and intramolecularity of the Stevens [1,2] rearrangement of the ylide (1) has been examined; the results are compatible with two possible mechanisms: (i) a radical pair mechanism with an average geminate recombination rate which is exceptionally fast, or (ii) dual pathways involving concurrent radical pair and concerted processes.

Structural studies in main-group chemistry. Part IX. Crystal structure of chlorotrimethyl(triphenylphosphoranylideneacetone)tin(IV)

Abstract: The crystal structure of the title compound has been determined from X-ray diffractometer data by Patterson and Fourier methods. Crystals are monoclinic, space group P21/c with a= 9.303(2), b= 10.221 (2), c= 26.338(4)A, β= 102.43(1)°, Z= 4. The tin atom possesses a trigonal bipyramidal configuration with the three methyl groups occupying equatorial positions [mean r(Sn–C) 2.133 A] in a planar arrangement. The two axial sites are occupied by the chlorine atom [r(Sn–Cl) 2.56 A] and the phosphorus ylide residue which functions as a unidentate oxygen-donor ligand [r(Sn–O) 2.332 A]. The structural parameters of the ylide skeleton indicate strong electron-withdrawal from the P:C bond towards the acetyl group.

Trimethylstannylethylidenetriphenylphosphorane. A new reagent for organic synthesis

Abstract: A new type of metalloalkyl ylide has been produced which can be used to convert a ketone or aldehyde function directly to a very nucleophilic double bond; this affords a method for preparing quaternary carbons either by ring closure or external electrophilic reaction.

Reactions of aryl glyoxylic esters with trivalent phosphorus compounds; the preparation of αβ-dimethoxycarbonylstilbene oxides

Abstract: A number of substituted αβ-dimethoxycarbonylstilbene oxides has been prepared by reductive condensation of the corresponding methyl phenylglyoxylates with hexamethylphosphorous triamide; these oxirans undergo [3 → 2 + 1] photocycloelimination to give aryl methoxycarbonylcarbenes and exhibit photochromic behaviour at 77K in rigid matrices, indicative of carbonyl ylide formation.

Secondary Deuterium Isotope Effects on Carbonyl Ylide Intermediates

Abstract: The formation of vinyldihydrofuran (6) and dihydrooxepine (5) is sensitive to deuterium substitution at the terminal methylene of 2,3-divinyloxirane. Intra- and intermolecular isotope effects have been examined and suggest that 5 is produced on a competitive basis with 6 from a common intermediate.

Keten. Part 15. Reactions of diphenylketen with some N-alkyl nitrones

Abstract: N-(Fluoren-9-ylidene)alkylamine N-oxides (1) react with diphenylketen to give spiro-oxazolidinones (2) and spiro-azetidinones (13). The adduct (2d) dissociates thermally to give the ylide (9). The N-oxides (1) behave like normal nitrones in cycloaddition reactions with dipolarophiles.

Solvent effects on the rates of hydrolysis of phosphonium ylides and salts

Abstract: The rate of hydrolysis of triphenylbenzyl-phosphonium hydroxide, produced from the bromide or the corresponding ylide, may be increased by a factor of > 105 by reducing the water content of the medium.

Electron‐impact‐induced rearrangements in the mass spectra of phosphinyl stabilized triphenylphosphonium ylides

Abstract: Examination of the mass spectra of some methyl and phenyl phosphonate stabilized triphenylphosphonium ylides revealed that these compounds are quite stable to electron-impact and provided valuable structural information. They exhibit strong molecular and [M - H]+ ions, and fragment ions which are characteristic for the phosphonium or the phosphonate portion of the molecules. Numerous rearrangement ions were detected, however, the most prominent of which involves the migration of a phosphonate phenyl to the ylide carbon, leading to the base peak (m/e 352) in the spectrum of diphenyl triphenylphosphoranylidenemethylphosphonate. The mechanism of these fragmentations has been studied with the aid of high resolution analysis and deuterium labeled analogs whose preparation is reported.

Mesoionische Sechsringheterocyclen, V Pyridinium-Ylide von Malonylheterocyclen / Mesoionic Sixmembered Heterocycles, V Pyridinium Ylides of Malonylheterocycles

Abstract: The reaction of 3,3-dichloro-2,4-dioxo-tetrahydroquinolines with pyridine yields the corresponding pyridinium ylides. However, the reaction of 3-diazo-2,4-dioxo-tetrahydroquinolines with pyridine in the presence of copper gives Cu complexes of 4,4′-dihydroxy-3,3′-azo-2-quinolones.

Insertion of Cyclohexyl Isocyanide into a Palladium Ylide Complex

Abstract: Cyclohexyl isocyanide reacted with N-trimethylsilylimino-phosphoranedichloropalladium dimer complex (I) giving monomeric isocyanide coordinated palladium complex (II) as an initial product. Further reaction of excess of isocyanide with (II) resulted in insertion of isocyanide into the palladium-nitrogen bond of complex (II). Carbon monoxide reacted similarly with the complex (I).

Chelate phosphorus ylide complexes of palladium and platinum.

Abstract: Several bidentate phosphorus ylide ligands of the type Ph2P–(CH2)n–P+(Ph2)–C−H–C(O)–R (n = 1, R = Ph; n = 2, R = CH3, OCH3) and their complexes of palladium(II) and platinum(II) chlorides have been synthesized and characterized.

Ylides du soufre dérivés de sucres Communication préliminaire

Abstract: S-Methylation of 6-S-benzyl-6-deoxy-1,2-O-isopropylidene-3-O-methyl-α-D-xylo-6-thiohexofuranos-5-ulose (1) gave the expected sulfonium salt 2 which on alcaline treatment yielded the stable sulfur ylide 3. This compound constitutes an useful synthetic intermediate in carbohydrate chemistry. On heating in 1,2-dimethoxyethane, it underwent a Stevens rearrangement which led to an extension of the carbon chain of the sugar and, reacted with Michael acceptors, it gave cyclopropanation reactions.

Synthesis and reaction of new type i-n ylide, n-tosyliminoiodinane

Abstract: Die Diacetoxyjodarylverbindungen (I) reagieren mit p-Toluolsulfonamid (II) in Gegenwart von Basen zu den J -N-Yliden (III).

Process for preparing Δ22 -25-oxy substituted sterol derivatives

Abstract: A new method of preparing 3α,5α-cyclo-6β-alkoxy-Δ 22 -25-oxy or acyloxy bisnorcholestane and analogues which involves reacting a bisnorcholanaldehyde with an ylide. Novel cholestanes and i-ethers are also claimed.

Reactions of 1λ5σ4,2,4-triazoline-3,5-dione decomposition products with organophosphorus nucleophiles

Abstract: The reactions of 1,1-dialkyl-4-t-butyl-1λ5σ4,2,4-triazoline-3,5-diones, under conditions known to produce N-isocyanato dialkylamines and t-butyl isocyanate, with various phosphorus compounds have been investigated. With phosphonium ylides the products depend on the phosphonium compound; highly stable or highly reactive ylides give products derived from t-butyl isocyanate, whereas ylides of intermediate stability react with the N-isocyanato-amine. The former products were independently synthesised from the phosphonium ylide and t-butyl isocyanate. Reactions with iminophosphoranes gave carbodi-imides, but only through reaction with t-butyl isocyanate; in no case were products derived from reaction with N-isocyanato-amine obtained. No evidence was observed for reaction with either N-isocyanato-amine or t-butyl isocyanate in experiments with a variety of phosphorus(III) compounds.

Formation of vinyl sulphides via successive sigmatropic rearrangements of an allylic sulphonium ylide

Abstract: It is shown that the sulphonium ylide (VIII) derived from the bisallylic sulphonium salt bis-(2,3-dimethoxycarbonylprop-2-enyl)methylsulphonium tetrafluoroborate (VII) undergoes a [2,3] sigmatropic rearrangement to produce the diastereoisomers (IX) and (X) of tetramethyl 3-(methylthio)hexa-1,5-diene-1,2,4,5-tetracarboxylate. The stereochemical outcome of the Cope rearrangements of the sulphides (IX) and (X) to (E,E)- and (Z,E)-tetramethyl 6-(methylthio)hexa-1,5-diene-1,2,4,5-tetracarboxylate (XI) and (XII), respectively, is invoked to determine the relative configurations at the chiral centres of (IX) and (X).