Addition Of Ylides Research Articles

Zur Reaktion von Metall-koordiniertem Kohlenmonoxid mit Yliden, X [1] β-Phosphoniocarben-, β-Phosphonio vinyl-und Phosphor-Ylid-Komplexe des Chroms und Cobalts aus Tetramethylphosphonium- [(trimethylphosphoranyliden)acetyl-metallaten] / Reactions of Metal Coordinated Carbon Monoxide with Ylides, X [1] β-Phosphoniocarbene, β-Phosphoniovinyl and Phosphorus Ylide Complexes of Chromium and Cobalt Deriving from Tetramethylphosphonium [(trimethylphosphoranyliden)- acetyl-metallates

Abstract The reaction of Cp(CO)2(NO)Cr with Me3P = CH2 yields the tetramethylphosphonium -[(trimethylphosphoranyliden)acetyl-Chromate] Me4P[Cp(CO)(NO)Cr-C(O)-CH = PMe3] (1) via ylide addition at the carbonyl carbon and transylidation. A reversible equilibrium is established between 1 and the starting materials, which is responsible for the facile conversion of 1 into the ylide complex Cp(CO)(NO)Cr-CH2PMe3 (2) on photolysis. In the presence of Mel, 1 is degradated to [Me4P]I, [Me3PEt]I, [Me2PEt2]I and Cp(CO)2(NO)Cr. Treatment of 1 with an equimolar amount of MeOSO2F leads to the formation of the "zwitterionic" phosphoniovinyl complexes Cp(CO)(NO)Cr-C(OMe) = CH-PMe3 (3a) and Cp(CO)(NO)Cr-C(OMe) = C(Me)-PMe3 (3b). With excess MeOSO2F the phosphoniocarbene complex [Cp(CO)(NO)Cr = C(OMe)-CH(Me)-PMe3]SO3F (4a) is obtained. Me3P = CH2 de-protonates 4a to 3b, which adds HCl to give [Cp(CO)(NO)Cr=C(OMe)-CH(Me)-PMe3]Cl (4b). The phosphonium cobaltacylates Me4P[(CO)(NO)(L)CO-C(O)-CH = PMe3] (5a, b), generated from the cobalt complex (CO)2(NO)(L)Co (L = CO, Me3P) and Me3P = CH2, readily transform to the ylide complexes (CO)(NO)(L)Co-CH2-PMe3 (6a, b). MeX (X = I, SO3F) cleaves 6b to give (CO)2(NO)(Me-P)Co and [Me3PEt]X. The new complexes are characterized by elementary analysis and spectroscopy.

ChemInform Abstract: THE REACTION OF THIO‐SUBSTITUTED CYCLOPROPENIUM IONS WITH SULFONIUM METHYLIDE

The reaction between thio-substituted cyclopropenium ions and sulfonium methylides gives unanticipated ketene derivatives. This reaction is supposed to proceed through an intermediate sulfonium salt formed from ylide addition to the cyclopropenyl ring.

The Reaction of Thio-substituted Cyclopropenium Ions with Sulfonium Methylide

Abstract The reaction between thio-substituted cyclopropenium ions and sulfonium methylides gives unanticipated ketene derivatives. This reaction is supposed to proceed through an intermediate sulfonium salt formed from ylide addition to the cyclopropenyl ring.

ChemInform Abstract: STUDIES ON INTRAMOLECULAR ALKYLATION. XII. STEREOCHEMICAL ASPECTS OF THE PREPARATION OF β,Γ‐UNSATURATED ALDEHYDES FROM THE (2,3)‐SIGMATROPIC REARRANGEMENT OF AMMONIUM YLIDES

AbstractEine sigmatrope Umlagerung des Allylammoniumylids (I), verbunden mit einer sauren Hydrolyse des entstehenden Gemisches isomerer Umlagerungsprodukte (II), liefert in hoher Ausb. ein Gemisch diastereomerer ungesättigter Aldehyde, in dem das trans‐Isomere (III) mit äquatorial stehender Formylgruppe stark überwiegt.

Total Reversibility of the Addition and Transylidation of Trialkyl(alkylidene)phosphoranes to Metal‐Coordinated Carbon Monoxide

The reactivity of phosphorus ylides towards carbonyl(cyclopentadienyl) complexes has been examined for the first time in the case of MeC5H4(CO)3Mn. This complex reacts with Me3PCH2 (molar ratio 1:2) via ylide addition and transylidation to give the phosphorylated phosphonium manganoacylate (1), in a completely reversible reaction. The starting materials are recovered on dissolution of (1).

Addition of diazomethane and sulfur ylides to the carbonyl group in derivatives of ketoses and aldoses-III: Reactions of 1,2-dideoxy-4,5- O-isopropylidene- d- glycero-3-pentulose

The reactions of diazomethane and dimethyloxo-sulfonium methylide with 1,2-dideoxy-4,5- O-isopropylidene- d- glycero-3-pentulose were studied. The sulfur ylide yielded two epimeric epoxides while diazomethane in addition furnished a homologous ketone. The reaction with diazomethane was carried out with varying concentrations of methanol in the reaction medium, and the relative yields of the three products were determined in each case. The results were explained on the basis of a two-step reaction mechanism proposed earlier. Steric effects and complexation between the positive nitrogen and one of the oxygens were inferred to be important.

Addition of Diazomethane and Sulfur Ylides to the Oxo-group in Derivatives of Ketoses and Aldoses. Part 2. Reactions of 1-Deoxy-3,4-O-isopropylidene-D-glycero-tetrulose and 1-Deoxy-3,4:5,6-di-O-isopropylidene-L-arabino-hexulose.

Addition of Diazomethane and Sulfur Ylides to the Oxo-group in Derivatives of Ketoses and Aldoses. Part 2. Reactions of 1-Deoxy-3,4-O-isopropylidene-D-glycero-tetrulose and 1-Deoxy-3,4:5,6-di-O-isopropylidene-L-arabino-hexulose.

Addition of diazomethane and sulfur ylides to the oxo-group in derivatives of ketoses and aldoses : I. Reactions of 2,3-O-isopropylidene-D-glyceraldehyde

The reaction between 2,3-O-isopropylidene- D-glyceraldehyde and diazomethane, dimethylsulfonium methylide and dimethyloxosulfonium methylide has been studied. The sulfur ylides yield two epimeric epoxides, 1,2-anhydro-3,4-O-isopropylidene- D-erythritol and 1,2-anhydro-3,4-O-isopropylidene- D-threitol, with a slight preference for the erythro isomer. The reaction with diazomethane yields in addition to the epoxides a methyl ketone, 1-deoxy-3,4-O-isopropylidene- D- glycero-tetrulose. The relative yields of the three products have been discussed on the basis of mechanisms previously proposed for the reactions. The yield of methyl ketone was lowest when the reaction was carried out in pure diethyl ether solution. This solvent also gives the greatest preference for the erythro isomer of the two epoxides. Constitution and stereochemistry for the three products have been shown by synthesis.

ChemInform Abstract: STUDIES ON HETEROCYCLIC ANALOGS OF AZULENES. IV. BEHAVIOR OF 2‐CHLOROCYCLOHEPTA(B)PYRROLE DERIVATIVES TOWARD PHOSPHORUS YLIDE

AbstractDie Untersuchung der Titelreaktion zeigte, daß die 3,8‐disubstituierten Derivate (Ia) und (Ib) jeweils nur ein Transylidierungsprodukt (IIIa) bzw. (IIIb) liefern, während die 3‐substituierten Derivate (Ic) und (Id) zu komplexen Reaktionsmischungen führen, die aus (IIIc), (IV) und (V) bzw. (IIId) und kleinen Mengen von instabilen, nicht identifizierten Verbindungen bestehen.

Studies on Heterocyclic Analogs of Azulenes. IV. Behavior of 2-Chlorocyclohepta[b]pyrrole Derivatives toward Phosphorus Ylide

Abstract The transylidation reaction of methyl(triphenylphosphoranylidene)acetate with 2-chlorocyclohepta[b]pyrrole derivatives has been studied. 3,8-Disubstituted derivatives gave a transylidation product only, whereas 3-substituted derivatives afforded not only a transylidation products but also the compounds formed by the addition of ylide at C-8. 13C NMR spectra of the transylidation products are recorded in part.

Réactivité des ylures d'isoquinoléinium: Etude par ESCA de la réaction d'echange de substituant

The reactivity of isoquinolinium methylides has been studied by ESCA and CNDO/2 calculations of charge density distribution, the negative charge of the ylide carbon is mainly delocalized on electron withdrawing substituents. This fact suggests a novel reaction mechanism involving a 1,2-cycloaddition to a ketene intermediate, a mechanism already invoked to explain pyridinium ylide addition reactions to acetylenic derivatives.