نتایج جستجو برای: 13 dicarbonyl
تعداد نتایج: 333355 فیلتر نتایج به سال:
Diketoreductase catalyzes a two-step bioreduction on a dicarbonyl substrate through a novel dual catalysis mode, in which random hydride attack simultaneously forms two mono-carbonyl intermediates, and subsequently distinct catalytic sites are responsible for the reductions of respective carbonyl group of the intermediates to yield the final dihydroxy product.
An efficient synthesis of novel 4-(2-phenyl-1,2,3-triazol-4-yl)-3,4-dihydro-pyrimidin-2(1H)-(thio)ones from 1,3-dicarbonyl compounds, 2-phenyl-1,2,3-triazole-4-carbaldehyde and urea or thiourea under ultrasound irradiation and using samarium perchlorate as catalyst is described. Compared with conventional methods, the main advantages of the present methodology are milder conditions, shorter rea...
An enantioselective intramolecular Conia-ene reaction of beta-dicarbonyl compounds and alkynes to afford methylene cyclopentanes is described. The reaction employs a DTBMSegphos-Pd(II)/Yb(III) dual catalyst system that allows for the asymmetric synthesis of all-carbon quaternary centers and generates a product containing an alkene that can be further manipulated.
A wide variety of chiral succinimides have been prepared in high yields and enantioselectivities by an asymmetric conjugate addition of 1,3-dicarbonyl compounds to maleimides under very mild reaction conditions using the bifunctional benzimidazole-derived organocatalyst 5f. Computational and NMR studies support the hydrogen-bonding activation role of the catalyst and the origin of the stereosel...
A simple metal-free, step-economic and selective access to pyridines from readily available substrates is reported, involving a flexible 4 A molecular sieves promoted Michael addition initiated domino three-component reaction between a 1,3-dicarbonyl, a Michael acceptor and a synthetic equivalent of ammonia.
Mn(III)-mediated reactions of 2-isocyanobiaryls with 1,3-dicarbonyl compounds were described for the construction of 6-alkylated and 6-monofluoro-alkylated phenanthridines in moderate to good yields. The reaction involves formation of two new C-C bonds and one C-C bond cleavage.
A novel visible light promoted carbodifluoroalkylation of allylic alcohols is disclosed. A series of difluoro 1,5-dicarbonyl compounds were obtained through a tandem radical addition and 1,2-aryl migration process. Mechanistic analysis indicated that the 1,2-aryl rearrangement proceeded via a radical intermediate.
An efficient method for the synthesis of β-enaminones and β-enaminoesters using a combination of [(PPh(3))AuCl]/AgOTf as catalyst has been developed. The reaction between 1,3-dicarbonyl compounds and primary amines was carried out under solvent-free conditions with low catalyst loading in good to excellent yields at room temperature.
A general evaluation of silylated nucleophiles to intercept transient α-oxoketenes generated by microwave-assisted Wolff rearrangement of 2-diazo-1,3-dicarbonyl compounds is presented. Original scaffolds and synthetic intermediates are accessed in a rapid, efficient and easy-to-handle way. Mechanistic studies by DFT calculations and some post-functionalizations are discussed.
The reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform afforded silica bonded S-sulfonic acid (SBSSA), which was used as a catalyst for the room temperature synthesis of quinoxaline derivatives from 1,2-diamino compounds and 1,2-dicarbonyl compounds. The catalyst could be recycled and reused several times without any loss of efficiency.
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