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Multiple-component condensations (MCC) where three or more reactants combine to afford a new core structure possessing the molecular features of its composite building blocks is a powerful method for the preparation of molecular diversity. We have developed an efficient, nickel-catalyzed, Reformatsky-type three-component condensation (3CC) reaction that affords beta-amino carbonyl compounds. The scope of the reaction is demonstrated both in the gram and microscale settings; 15 beta-amino esters, amides, and a ketone were prepared efficiently at the mmol scale, and a library of 64 beta-amino carbonyl compounds was generated at the micromol scale. 相似文献
133.
Ladlow M Legge CH Neudeck T Pipe AJ Sheppard T Yang LL 《Chemical communications (Cambridge, England)》2003,(16):2048-2049
A method to effect photo-mediated differential release of bead-based compound libraries using a tuneable laser in combination with chromatically orthogonal photolabile linkers is described. 相似文献
134.
Analysis of additive metals in fuel and emission aerosols of diesel vehicles with and without particle traps 总被引:1,自引:0,他引:1
Fuel additives used in particle traps have to comply with environmental directives and should not support the formation of additional toxic substances. The emission of metal additives from diesel engines with downstream particle traps has been studied. Aspects of the optimisation of sampling procedure, sample preparation and analysis are described. Exemplary results in form of a mass balance calculation are presented. The results demonstrate the high retention rate of the studied filter system but also possible deposition of additive metals in the engine. 相似文献
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We report the observation of anisotropic domain-wall propagation in ultrathin magnetic films with perpendicular anisotropy. A controlled density of step edges was introduced which allowed us to quantify its influence on the domain-wall pinning. For a sawtooth arrangement of the step edges the corresponding wall movement resulted in triangular shaped domains. All aspects of this anisotropic domain-wall evolution could be reproduced by a simulation based on a modified Ginzburg-Landau-type soft-spin model. 相似文献
137.
Adrian K. Y. Lam Richard A. J. O'Hair 《Rapid communications in mass spectrometry : RCM》2010,24(12):1779-1790
A combination of electrospray ionisation (ESI), multistage and high‐resolution mass spectrometry experiments is used to examine the gas‐phase fragmentation reactions of the three isomeric phenylalanine derivatives, α‐phenylalanine, β2‐phenylalanine and β3‐phenylalanine. Under collision‐induced dissociation (CID) conditions, each of the protonated phenylalanine isomers fragmented differently, allowing for differentiation. For example, protonated β3‐phenylalanine fragments almost exclusively via the loss of NH3, only β2‐phenylalanine via the loss of H2O, while α‐ and β2‐phenylalanine fragment mainly via the combined losses of H2O + CO. Density functional theory (DFT) calculations were performed to examine the competition between NH3 loss and the combined losses of H2O and CO for each of the protonated phenylalanine isomers. Three potential NH3 loss pathways were studied: (i) an aryl‐assisted neighbouring group; (ii) 1,2 hydride migration; and (iii) neighbouring group participation by the carboxyl group. Finally, we have shown that isomer differentiation is also possible when CID is performed on the protonated methyl ester and methyl amide derivatives of α‐, β2‐ and β3‐phenylalanines. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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