نتایج جستجو برای: ketones
تعداد نتایج: 9200 فیلتر نتایج به سال:
A method for use in high-throughput screening of bacteria for the production of long-chain hydrocarbons and ketones by monitoring fluorescent light emission in the presence of Nile red is described. Nile red has previously been used to screen for polyhydroxybutyrate (PHB) and fatty acid esters, but this is the first report of screening for recombinant bacteria making hydrocarbons or ketones. Th...
10 Metastable ion decompositions of TMS+ adducts of all the saturated, acyclic C5–C7 ketones and of selected ketone conjugate acid ions are compared. The proportion of ions that result from rearrangement of the carbon skeleton tends to increase with the size of the starting ketone. Parent ions derived from -branched ketones can be subdivided into pairs that rearrange and decompose via common in...
We report the development of direct catalytic, enantioselective, anti-selective Mannich-type reactions between unmodified ketones and alpha-imino esters under mild conditions. The reactions were performed using 5-10 mol % of (R)-3-pyrrolidinecarboxylic or (R)-beta-proline as catalyst in an environmentally benign solvent, 2-PrOH, at room temperature. The anti-Mannich products were obtained in go...
In this paper, the origins of enantioselectivity in asymmetric ketone hydrogenation catalyzed by RuH(2)(binap)(cydn) (cydn = trans-1,2-diaminocyclohexane) were discussed. Fifteen substrates involving aromatic, heteroaromatic, olefinic and dialkyl prochiral ketones were used to probe the catalytic mechanism and find an effective way to predict the chirality of the products. The calculated result...
In an environmentally benign solventless system, aldehydes and ketones were readily converted to their corresponding azines with hydrazine sulfate, sodium hydroxide and alumina in high yield.
β -Acetamido ketones are valuable building blocks for the preparation of β -amino ketones or β -amino alcohols such as the antibiotic nikkomycins [1] and neopolyoxines [2]. α-Acetamido ketones are obtained in the Dakin-West reaction [3] and β -acetamido ketones by the Iqbal route. In the latter, an aromatic aldehyde, an enolizable ketone and acetonitrile are condensed in the presence of acetyl ...
The phenomenon of beta-phenyl quenching has been examined by laser-flash photolysis in a series of alpha- and/or beta-substituted ketones 4-8 with similar excited-state characteristics. It is found that alpha-substitution markedly increases the triplet lifetimes in contrast to beta-substitution. The force field calculations for the various staggered conformers of ketones 4-6 and 8-syn show that...
Eight ruminally cannulated Holstein bull calves were used in a switchback design to evaluate effects of hay on postprandial changes in ruminal pH, ammonia and VFA, blood ketones, and plasma glucose, NEFA, VFA, and urea N. Calves were fed 4.5 kd/d of calf starter with or without hay for ad libitum consumption. Blood and ruminal fluid were sampled every 2 h for 12 h on d 21 (periods 1 and 2) or d...
high enantioselectivity and good yield were observed for aryl methyl ketones, with a modest drop in enantioselectivity for electron-poor substrates. Other aryl ketones gave rise to good to excellent e.r.’s, as highlighted by substrate 2h. Heteroaromatics were also well tolerated under the reaction conditions, with thiopheneand furan-derived ketones undergoing highly enantioselective propargylat...
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