N-Fluoropyridinium salts provide a new system of fluorinatingagents by which a wide range of nucleophilic substrates differing in reactivity can be fluorinated due to the varying degree of fluorinating power and also fluorinated very selectively through structural alteration. The scope of selective fluorination should be broadened considerably on the basis of the present results. The N-fluoropyridinium
rate-determining C−C bond formation. The nucleophilic reactivities span over a range of 108 from the vinylethers 1a,x as the least reactivecompounds (comparable to allylsilanes) to the highly nucleophilic silyl ketene acetal 1u (comparable to enamines). Linear free enthalpy relationships are used to compare the reactivities of these compounds with those of other aliphatic and aromatic π-nucleophiles.
Nucleophilic addition of silyl enol ethers to aromatic nitro compounds: scope and mechanism of reaction
作者:T. V. RajanBabu、G. S. Reddy、Tadamichi Fukunaga
DOI:10.1021/ja00305a024
日期:1985.9
chloride are not displaced in the reaction, suggesting the absence of radical ion intermediates. Dihydroaromatic nitro derivatives can be isolated in some cases, such as anthracene and naphthalene systems which are less prone to rearomatize. The use of silicon reagents in organic synthesis has been ex- panding rapidly in the past few year^,^-^ and versatile methods for carbon-carbon bond formations have been
Copper-Catalyzed γ-Selective and Stereospecific Allylic Alkylation of Ketene Silyl Acetals
作者:Dong Li、Hirohisa Ohmiya、Masaya Sawamura
DOI:10.1021/ja111645q
日期:2011.4.20
Copper-catalyzed allylic alkylation of ketene silyl acetals proceeded with excellent γ-E-selectivity. Efficient α-to-γ chirality transfer with anti-selectivity occurred in the reaction of enantioenriched secondary allylic phosphates, affording enantioenriched β-branched γ,δ-unsaturated esters. Excellent functional group compatibility was observed.
Sodium Phenoxide−Phosphine Oxides as Extremely Active Lewis Base Catalysts for the Mukaiyama Aldol Reaction with Ketones
作者:Manabu Hatano、Eri Takagi、Kazuaki Ishihara
DOI:10.1021/ol702052r
日期:2007.10.1
A highly efficient Mukaiyama aldolreaction between ketones and trimethylsilyl enolates catalyzed by sodium phenoxide-phosphine oxides as simple homogeneous Lewis base catalysts (0.5-10 mol %) was developed, which minimized competing retro-aldolreaction. For a variety of aromatic ketones and aldimines, aldol and Mannich-type products with an alpha-quaternary carbon center were obtained in good to