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Interrupted Baeyer–Villiger Rearrangement: Building A Stereoelectronic Trap for the Criegee Intermediate 下载免费PDF全文
Dr. Vera A. Vil' Gabriel dos Passos Gomes Oleg V. Bityukov Prof. Konstantin A. Lyssenko Prof. Gennady I. Nikishin Prof. Igor V. Alabugin Prof. Alexander O. Terent'ev 《Angewandte Chemie (International ed. in English)》2018,57(13):3372-3376
The instability of hydroxy peroxyesters, the elusive Criegee intermediates of the Baeyer–Villiger rearrangement, can be alleviated by selective deactivation of the stereoelectronic effects that promote the 1,2‐alkyl shift. Stable cyclic Criegee intermediates constrained within a five‐membered ring can be prepared by mild reduction of the respective hydroperoxy peroxyesters (β‐hydroperoxy‐β‐peroxylactones) which were formed in high yields in reaction of β‐ketoesters with BF3?Et2O/H2O2. 相似文献
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The total synthesis of a didemnin B analogue containing a conformationally constrained replacement for the isostatine moiety is reported. Synthetic highlights include an improved preparation of 2-hydroxy-3-cyclohexenecarboxylic acid and a new strategy for accessing the macrocycle. 相似文献
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Vera B. Ivleva Nicole A. Schneck Deepika Gollapudi Frank Arnold Jonathan W. Cooper Q. Paula Lei 《Journal of the American Society for Mass Spectrometry》2018,29(7):1512-1523
CAP256 is one of the highly potent, broadly neutralizing monoclonal antibodies (bNAb) designed for HIV-1 therapy. During the process development of one of the constructs, an unexpected product-related impurity was observed via microfluidics gel electrophoresis. A panel of complementary LC-MS analyses was applied for the comprehensive characterization of CAP256 which included the analysis of the intact and reduced protein, the middle-up approach, and a set of complementary peptide mapping techniques and verification of the disulfide bonds. The designed workflow allowed to identify a clip within a protruding acidic loop in the CDR-H3 region of the heavy chain, which can lead to the decrease of bNAb potency. This characterization explained the origin of the additional species reflected by the reducing gel profile. An intra-loop disulfide bond linking the two fragments was identified, which explained why the non-reducing capillary electrophoresis (CE) profile was not affected. The extensive characterization of CAP256 post-translational modifications was performed to investigate a possible cause of CE profile complexity and to illustrate other structural details related to this molecule’s biological function. Two sites of the engineered Tyr sulfation were verified in the antigen-binding loop, and pyroglutamate formation was used as a tool for monitoring the extent of antibody clipping. Overall, the comprehensive LC-MS study was crucial to (1) identify the impurity as sequence clipping, (2) pinpoint the clipping location and justify its susceptibility relative to the molecular structure, (3) lead to an upstream process optimization to mitigate product quality risk, and (4) ultimately re-engineer the sequence to be clip-resistant. 相似文献
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Extended Hückel theory calculations have been carried out to investigate the possible formation of stable π and σ complexes between olefins and some hydrocarbonylirons postulated as active catalysts in Reppe synthesis. It was found that H2Fe(CO)4 and HFe(CO)4- do not coordinate ethylene, unlike the corresponding CO deficient species H2Fe(CO)3 and HFe(CO)3-, which interact with the olefin to give stable π complexes. Moreover ethylene—H2Fe(CO)3 is more stable than ethylene—HFe(CO)3-, in line with the conclusions based on the experimental results. Stable alkyl intermediates are predicted starting from the coordinatively saturated hydrocarbonyls. 相似文献
66.
Mathematical theory of optimization has found many applications in the area of medicine over the last few decades. Several
data analysis and decision making problems in medicine can be formulated using optimization and data mining techniques. The
significance of the mathematical models is greatly realized in the recent years owing to the growing technological capabilities
and the large amounts of data available. In this paper, we attempt to give a brief overview of some of the most interesting
applications of mathematical programming and data mining in medicine. In the overview, we include applications like radiation
therapy treatment, microarray data analysis, and computational neuroscience. 相似文献
67.
Experiments are presented elucidating how the evolution of foam microstructure by gas diffusion from high to low pressure bubbles can significantly speed up the rate of gravitational drainage, and vice versa. This includes detailed data on the liquid-fraction dependence of the coarsening rate, and on the liquid-fraction and the bubble-size profiles across a sample. These results can be described by a "coarsening equation" for the increase of bubble growth rate for drier foams. Spatial variation of the average bubble size and liquid fraction can also affect the growth and drainage rates. 相似文献
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