نتایج جستجو برای: silyl ethers
تعداد نتایج: 8150 فیلتر نتایج به سال:
α,β-Unsaturated ketones and aldehydes have been synthesized from their corresponding silyl enol ethers in a straightforward protocol involving a visible-light promoted organocatalytic, aerobic oxidation reaction. A cheap organic dye was used catalytically in these reactions as the photosensitizer.
Abstract: By utilizing the characteristic features of vinylsulfides, 2-(alkylthio)allyl silyl ethers were designed as efficient ene substrates, and their use led to exploration of general carbonyl and imine ene reactions. By using 3-(alkylthio)-2-siloxyallyl acetates, a useful [3 + 2]cyclopentane annulation methodology was developed. Further, a tandem CC bond formation/cleavage methodology was ...
A synthetic approach for tropane alkaloids on the basis of tandem (domino) ene-type reactions of acetone silyl enol ethers with iminium ions is shown to be triggered by intermolecular ene-type reactions followed by 6-(2,5) silatropic ene-type cyclizations.
We report an efficient Mukaiyama-aldol reaction of tryptanthrin with fluorinated enol silyl ethers, which is carried out in methanol without the use of any catalyst. This method is applied to the total synthesis of the difluoro analogues of the natural product Phaitanthrin B.
Versatile and base-free copper-catalyzed ?-arylations of aromatic ketones using diaryliodonium salts
A ligand and base-free copper catalyzed synthetic method for the efficient ?-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided intermolecular C–C coupling displaying good functional group tolerance requiring low catalyst loading.
The kinetics of the reactions of benzhydryl cations with eight diazo compounds 1 a-g were investigated photometrically in dichloromethane. The nucleophilicity parameters N and slope parameters s of these diazo compounds were derived from the equation log k (20 degrees C)=s (E+N) and compared with the nucleophilicities of other pi systems (alkenes, arenes, silyl enol ethers, silyl ketene acetals...
A catalytic, enantioselective, Lewis base-catalyzed α-sulfenylation of silyl enol ethers has been developed. To avoid acidic hydrolysis of the silyl enol ether substrates, a sulfenylating agent that did not require additional Brønsted acid activation, namely N-phenylthiosaccharin, was developed. Three classes of Lewis bases-tertiary amines, sulfides, and selenophosphoramides-were identified as ...
A palladium (Pd)-catalyzed endo-selective Heck reaction of iodomethylsilyl ethers of phenols and aliphatic alkenols has been developed. Mechanistic studies reveal that this silyl methyl Heck reaction operates via a hybrid Pd-radical process and that the silicon atom is crucial for the observed endo selectivity. The obtained allylic silyloxycycles were further oxidized into (Z)-alkenyldiols.
A highly enantioselective method for the catalytic Mukaiyama aldol reaction of silyl enol ethers with aldehydes in aqueous conditions was developed. The desired aldol products were obtained in excellent yields, diastereo- and enantioselectivities. Structural evidence of the pre-catalyst revealed an unprecedented heptadentate Fe(II) complex with the chiral bipyridine ligand.
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