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101.
Kyle M. Lambert Joshua B. Cox Lin Liu Amy C. Jackson Sam Yruegas Kenneth B. Wiberg John L. Wood 《Angewandte Chemie (International ed. in English)》2020,59(24):9757-9766
The development of a concise total synthesis of (±)‐phyllantidine ( 1 ), a member of the securinega family of alkaloids containing an unusual oxazabicyclo[3.3.1]nonane core, is described. The synthesis employs a unique synthetic strategy featuring the ring expansion of a substituted cyclopentanone to a cyclic hydroxamic acid as a key step that allows facile installation of the embedded nitrogen‐oxygen (N?O) bond. The optimization of this sequence to effect the desired regiochemical outcome and its mechanistic underpinnings were assessed both computationally and experimentally. This synthetic approach also features an early‐stage diastereoselective aldol reaction to assemble the substituted cyclopentanone, a mild reduction of an amide intermediate without N?O bond cleavage, and the rapid assembly of the butenolide found in ( 1 ) via use of the Bestmann ylide. 相似文献
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A Genetic Algorithm (GA) is an evolutionary computation technique inspired by the principle of biological evolution via natural
selection. It employs the fundamental components of evolution, such as selection, mating, and mutation, which continue from
generation to generation, creating better solutions as time progresses. Although it is mostly used as an optimization tool,
GA enjoys a wide spectrum of applications in diverse fields such as engineering, medicine, and ecology, among others. In this
study, we propose three different population size reduction methods for a typical GA optimization, aiming to increase efficiency.
Additionally, we compare the accuracy and precision of these methods using Monte Carlo simulations. 相似文献
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Application-specific optimization of disordered nanoporous carbons remains a formidable challenge due to the difficulty in
accurately characterizing their microstructures with current empirical methods. Using molecular simulation techniques, we
investigated the adsorptive and diffusive behavior of argon in three models of disordered nanoporous carbons. We found that
the structural and morphological differences between these models gave rise to distinct phenomenological properties. The adsorptive
behavior of argon in both the low and high pressure regimes was enhanced dramatically in the models with more crystalline
microstructures. As for dynamic properties, we found that the adsorbent’s structure and energetic topology significantly alters
the rates of diffusion as well as the characteristics of the underlying diffusion mechanisms. 相似文献
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This paper concerns the generation of support vector machine classifiers for solving the pattern recognition problem in machine
learning. A method is proposed based on interior-point methods for convex quadratic programming. This interior-point method
uses a linear preconditioned conjugate gradient method with a novel preconditioner to compute each iteration from the previous.
An implementation is developed by adapting the object-oriented package OOQP to the problem structure. Numerical results are
provided, and computational experience is discussed. 相似文献