16475-90-4Relevant articles and documents
Energy efficiency in chemical reactions: A comparative study of different reaction techniques
Gronnow, Mark J.,White, Robin J.,Clark, James H.,Macquarrie, Duncan J.
, p. 516 - 518 (2005)
Metrics for chemists are much argued, but the energy usage of a reaction has to be one of the most simple and effective methods of comparing technologies. In this concept paper, the energy consumed in preparing one mole of a chemical compound is compared for a variety of technologies. Data are gathered for traditional oil bath, supercritical CO2 (sc-CO 2), and microwave reactors. Two different Suzuki couplings, a Knoevenagel condensation, and a Friedel-Crafts acylation are all compared in both the microwave and oil bath, as this is where the most noticeable differences were observed. The most notable result was an 85-fold reduction in energy demand on switching from oil bath to microwave reactor for a Suzuki reaction.
Preparation method of free racemic albuterol
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Paragraph 0039; 0040, (2018/12/13)
The invention discloses a preparation method of free racemic albuterol. The preparation method comprises the following steps: with methyl salicylate as a raw material, successively carrying out Friedel-Crafts acylation and oxidation, carrying out condensation and borate reduction in pure water with a 'one-pot' method, carrying out ester group reduction and acetonylidene protection of crude albuterol with a 'one-pot' method, and carrying out deprotection and purification to obtain the free racemic albuterol. The preparation method has the advantages of high labor efficiency, low reaction reagent cost and high yield.
Enantioselective bromolactonization of conjugated (2)-enynes
Zhang, Wei,Zheng, Suqing,Liu, Na,Werness, Jenny B.,Guzei, Llia A.,Tang, Weiplng
supporting information; experimental part, p. 3664 - 3665 (2010/05/15)
"Chemical equation presented" A catalytic enantioselective syn-1,4-bromolactonization of conjugated (Z)-enynes was reported. Diastereomeric ratios >20:1 and up to 99% enantiomeric excesses were observed. Di-, tri-, and tetra-substituted bromoallenes were prepared together with lactone heterocycles efficiently and stereoselectively. Preliminary investigations suggest that the chiral catalyst may serve as a bifunctional reagent by interacting with both a carboxylic acid nucleophile and NBS electrophile.
Asymmetric transfer hydrogenation of ketones catalyzed by hydrophobic metal-amido complexes in aqueous micelles and vesicles
Wang, Fei,Liu, Hui,Cun, Linfeng,Zhu, Jin,Deng, Jingen,Jiang, Yaozhong
, p. 9424 - 9429 (2007/10/03)
Asymmetric transfer hydrogenation of ketones, especially α-bromomethyl aromatic ketones, catalyzed by unmodified, hydrophobic transition metal-amido complexes (TsDPEN-M), was performed successfully with significant enhancement of activity, chemoselectivity, and enantio-selectivity (up to 99% ee) in aqueous media containing micelles and vesicles. The hydrophobic catalyst, embedded in micelles constructed from the surfactant cetyltrimethylammonium bromide (CTAB), could be separated from the organic phase along with the products and was recycled for at least six times.
Mass tags for quantitative analysis
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, (2008/06/13)
The present invention relates generally to novel protein modification reagents for fractionation and quantitative (differential) profiling of proteins in a complex mixture. The reagents react with amino acids or other protein components or structures and function as mass tags. The present invention provides methods of making the protein modification reagents and methods of using the protein modification reagents for quantitative analysis of proteins.
Dual binding mode of methylmethanetriacetic acid to tripodal amidopyridine receptors
Ballester, Pablo,Capo, Magdalena,Costa, Antoni,Deya, Pere M.,Gomila, Rosa,Decken, Andreas,Deslongchamps, Ghislain
, p. 8832 - 8841 (2007/10/03)
A series of tripodal amidopyridine receptors capable of selective recognition of methylmethanetriacetic acid (MMTA) in organic solvents is described. Intramolecular hydrogen-bonding groups, built into some of the receptors, were designed as preorganization devices. Binding was studied by NMR titration, variable temperature NMR experiments, 2D-NMR, isothermal titration calorimetry, and single-crystal X-ray crystallography. The results reveal that a balancing act between inter- and intramolecular hydrogen-bonding interactions in the complexes governs both the dynamics and the geometry of binding. Receptor 1b (without intramolecular hydrogen-bonding groups) features a simple symmetric MMTA binding geometry with optimal enthalpic interactions. In sharp contrast, receptor 1a (with intramolecular hydrogen-bonding groups) reveals a temperature-dependent dual binding mode where MMTA can bind in two completely different geometries. The two solution binding geometries of 1a·MMTA were unraveled by NMR experiments and correlated to the X-ray structures.
Alternative routes to pterulone
Kahnberg, Pia,Lee, Choon Woo,Grubbs, Robert H,Sterner, Olov
, p. 5203 - 5208 (2007/10/03)
Two new synthetic routes to pterulone, a fungal metabolite possessing potent antifungal activity as an inhibitor of NADH/ubiquinone oxidoreductase, are reported.
Ytterbium triflate mediated selective deprotection of acetates
Sharma,Ilangovan
, p. 1963 - 1965 (2007/10/03)
Ytterbium triflate mediated selective deprotection of acetates in isopropyl alcohol at reflux temperature is reported. Unlike hafnium triflate, under the present reaction conditions aryl acetates also undergo deacetylation instead of Fries migration.
Polyketoenols and Chelates. New Types of Xanthyrones Lacking Enolised Side-chain Termini: their Reactions with Magnesium Methoxide
Baker, S. Richard,Crombie Leslie,Dove, Roderick V.
, p. 165 - 171 (2007/10/02)
Xanthyrones (4) and (8) as well as (9), (11) and (13) have been synthesised: blocking the side-chain terminus, which is normally enolised as in (5), by dicyano or cyano-ester end groups, leads to enolisation of the 3-acetylpyrone end as shown by n.m.r. data in CDCl3.The dicyanobismethoxycarbonyl representative (9) exists in the 1'-H form in CDCl3-CF3CO2H whilst in CDCl3 the tetraester (13) is a 3'-H form.Xanthyrone (11) is present mainly in the 3'-H form in CDCl3 but some enolate (12) is observed.All the xanthyrones are highly ionised in ethanol, (9) especially so.Treated with exess (>6 mol. equiv.) magnesium methoxide, xanthyrones (4) and (8) cyclise by an aldol pathway and (9) and (13) by an analogous Claisen pathway.This contrasts with dimethylxanthophanic enol (5) with undergoes a different type of Claisen cyclisation.The results accord with the view that cyclisation in the latter case involves a bischelate (20) and in the other cases monochelates, e.g. (22) and (25).Reactions of xanthyrones (4) and (8) with boiling water follow expected pathways.
