Ylides structure

Tetrazolo[5,1 -6][ 1,2,4]triazin-3-ones synthesis, 3, 392 Tetrazolyl radicals oxidation, 5, 60 Tetrazolyl ylides structure, 5, 793 Tetrenolin occurrence, 4, 706 Tetrodotoxin... 

Kondo maintained his interest in this area, and with his collaborators [62] he recently made detailed investigations on the polymerization and preparation of methyl-4-vinylphenyl-sulfonium bis-(methoxycarbonyl) meth-ylide (Scheme 27) as a new kind of stable vinyl monomer containing the sulfonium ylide structure. It was prepared by heating a solution of 4-methylthiostyrene, dimethyl-diazomalonate, and /-butyl catechol in chlorobenzene at 90°C for 10 h in the presence of anhydride cupric sulfate, and Scheme 27 was polymerized by using a, a -azobisi-sobutyronitrile (AIBN) as the initiator and dimethylsulf-oxide as the solvent at 60°C. The structure of the polymer was confirmed by IR and NMR spectra and elemental analysis. In addition, this monomeric ylide was copolymerized with vinyl monomers such as methyl methacrylate (MMA) and styrene. 

NMR spectroscopic studies f111,13C, and 31P) are consistent with the dipolar ylide structure and suggest only a minor contribution from the ylene structure.234 Theoretical calculations support this view.235 The phosphonium ylides react with carbonyl compounds to give olefins and the phosphine oxide. 

A number of silylated bismethylenephosphoranes (6) have been prepared and characterized by n.m.r. spectroscopy and X-ray structural analysis.6 X-ray analysis reveals that the novel ylide structure (7) is formed in the reaction of tri-(n-butyl)phosphine... 

It has been argued for the ylide structure on the basis of NMR data. See Yamamoto, Y. Schmidbaur, H. J. Chem. Soc., Chem. Commun. 1975, 668. A recent electron localization function study also argues for the ylidic structure. See Chesnut, D. B. Heteroat. Chem. 2000, 11, 341. 

Decarboxylation of 1,3-dimethylorotic acid in the presence of benzyl bromide yields 6-benzyl-1,3-dimethyluracil and presumably involves a C(6) centered nucleophilic intermediate which could nonetheless have either a carbene or ylide structure. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been used to explore the gas-phase reactions of methyl nitrate with anions from active methylene compounds anions of aliphatic ketones and nitriles react by the 5n2 mechanism and Fco reactions yielding N02 ions are also observed nitronate ions are formed on reaction with the carbanions derived from toluenes and methylpyridines. 

Among the possible CL2 compositions the number of compounds is limited and the chemistry of most compounds still remains undeveloped. The nucleophilic behavior is more pronounced in double ylide structures in which more negative charge is located at the carbon atom which favors the bent structure. Thus, less stable carbenes as donors L, such as C(NMe2)2 or CF2, give structures CL2 which... 

Fig. 5 Schematic representation of the ylene/allene form vs double ylide structure of CL2 compounds which is used for the formulas of the experimentally observed compounds...

Vinyl triphenylphosphonium ion has been found to react with cuprate reagents by nucleophilic addition, generating an ylide structure. This intermediate can then be... 

Tetrazolium salts and tetrazolium-5-ylide structures <84CHEC-I(5)79l> as well as new tetrazolium-A-ylide structures are also possible. These are covered in Sections 4.17.5, 4.17.7 and 4.17.8. 

The exact structure of carbonyl ylides has been the subject of a variety of theoretical investigations over the past few decades since their intermediacy was suggested in 1965 during the cycloaddition reaction of substituted epoxides (1). Houk et al. (2) has undertaken a detailed smdy of the carbonyl ylide structure and reactivity by the application of computational methods (Fig. 4.3). 

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