无约束优化问题的修正PRP共轭梯度法

本文通过结合牛顿法与PRP共轭梯度法提出一修正PRP方法,新方法中包含了二阶导数信息,在适当的假设下算法全局收敛,数值算例表明了算法的有效性.     

一个求解非线性不等式约束优化问题的带有共轭梯度参数的广义梯度投影算法

本文提出一个求解非线性不等式约束优化问题的带有共轭梯度参数的广义梯度投影算法.算法中的共轭梯度参数是很容易得到的,且算法的初始点可以任意选取.而且,由于算法仅使用前一步搜索方向的信息,因而减少了计算量.在较弱条件下得到了算法的全局收敛性.数值结果表明算法是有效的.     

A robust von Neumann minimax theorem for zero-sum games under bounded payoff uncertainty

The celebrated von Neumann minimax theorem is a fundamental theorem in two-person zero-sum games. In this paper, we present a generalization of the von Neumann minimax theorem, called robust von Neumann minimax theorem, in the face of data uncertainty in the payoff matrix via robust optimization approach. We establish that the robust von Neumann minimax theorem is guaranteed for various classes of bounded uncertainties, including the matrix 1-norm uncertainty, the rank-1 uncertainty and the columnwise affine parameter uncertainty.     

四元数辛李代数MAD子代数的共轭性

利用四元数理论,证明了四元数体上辛李代数为实半单李代数,其极大可交换ad-可对角化(简称MAD)子代数是相互共轭的.     

Enantioselective synthesis of a potential 1,5-syn-polyol C1–C24 subunit of (−)-caylobolide A

The synthesis of a possible 1,5-syn-polyol C1–C24 subunit resident in (−)-caylobolide A has been accomplished. The key reaction sequence was a repetitive protocol for the construction of the syn-1,5-diol segment by means of Ru-catalyzed cross-metathesis and boron-mediated allylation reactions.     

Microwave-Assisted Conjugate Addition of Pyrrole on Electron-Deficient Nitro-Olefins

Michael addition of pyrrole to β-nitrovinyl compounds were carried out using microwave methodology. Monosubstituted pyrroles were obtained selectively in a major amount. Formation of novel product obtained during one of the reactions was explained by the double addition to nitrostyrene.     

Study of Molecular Recognition of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-β-cyclodextrin Conjugate Covalently Immobilized on a Silica Surface

Interactions of a new porphyrin–β-cyclodextrin conjugate (1) with a number of aromatic compounds have been studied after covalent immobilization of 1 onto a solid matrix of 3-aminopropylated silica particles. The effects of both porphyrin and β-cyclodextrin moieties on interactions with achiral aromatic compounds were studied and the influence of the achiral porphyrin spacer on chiral recognition of binaphthyl derivatives by the β-cyclodextrin moiety of 1 is discussed.     

Concise and highly selective asymmetric synthesis of acosamine from sorbic acid

Diastereoselective conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl sorbate and subsequent chemo- and diastereoselective ammonium-directed olefinic oxidation of the resultant conjugate addition product {tert-butyl (3S,αR)-3-[N-benzyl-N-(α-methylbenzyl)amino]hex-4-ene} have been used as the key steps in a concise and highly selective asymmetric synthesis of the 2,3,6-trideoxy-3-aminohexose l-acosamine. This sequence of two chemical operations allows rapid assembly of the molecular architecture and facilitates the de novo asymmetric synthesis of methyl N,O-diacetyl-α-l-acosaminide in only 7 steps from commercially available sorbic acid in 15% overall yield.     

Novel chiral hydrogen bond donor catalysts based on a 4,5-diaminoxanthene scaffold: application to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes

Novel chiral hydrogen bond donor catalysts based on a 4,5-diamino-9,9′-dimethylxanthene skeleton were designed and synthesized. Among the phenylurea-amide hybrid molecules prepared from various natural/unnatural chiral amino acids, the phenylalanine-derived catalyst, and the proline-derived catalyst were successfully applied to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes. Using 2-acetylcyclopentanone and 2-methoxycarbonylcyclopentanone as prochiral nucleophiles, asymmetric conjugate addition to β-aryl nitroalkenes proceeded with good diastereoselectivity to provide the corresponding products bearing an all-carbon quaternary stereocenter in excellent yield with up to 95% ee.