Novel recoverable catalysts for asymmetric transfer hydrogenation

9-Amino(9-deoxy)epiquinine and 9-amino(9-deoxy)epicinchonine were applied in asymmetric transfer hydrogenation of aromatic ketones in both iridium and rhodium catalytic systems using i-propanol as the hydrogen source. Good to excellent conversions and enantioselectivities were observed with a variety of aromatic ketones. Moreover, the Ir complex and Rh complex of 9-amino(9-deoxy)cinchonine were recovered in high yields with dilute hydrochloric acid. The enantioselectivity of 1-phenylethanol was nearly maintained after six cycles.     

Metric inequalities and the Network Loading Problem

Given a simple graph G(V,E) and a set of traffic demands between the nodes of G, the Network Loading Problem consists of installing minimum cost integer capacities on the edges of G allowing routing of traffic demands.In this paper we study the Capacity Formulation of the Network Loading Problem, introducing the new class of Tight Metric Inequalities, that completely characterize the convex hull of the integer feasible solutions of the problem.We present separation algorithms for Tight Metric Inequalities and a cutting plane algorithm, reporting on computational experience.     

Diastereoselective syntheses of 2-amino propargyl alcohols. Chiral building blocks for enantiopure amino γ-lactones and 5-hydroxy-piperidinone derivatives

α-Dibenzylamino aldehydes, derived from the corresponding natural α-amino acids, react with metal acetylides to yield anti-amino propargyl alcohols in good yield and diastereomeric excess. syn Amino alcohols are prepared from the anti diastereoisomers and all of them are elaborated in few steps to enantiopure amino lactones and hydroxy-piperidin-2-ones.     

中国股票市场交易量与价格波动关系实证研究

利用个股数据资料和非对称成分GARCH-M模型对中国股票市场的量价关系进行了实证研究.结论显示:股价的短期波动主要由非预期交易量解释,即非预期交易量所揭示的新信息是产生价格波动的根源;中国股票市场部分个股存在明显的杠杆效应,利空消息对市场波动的冲击大于同等程度的利好消息对市场波动的冲击;非预期交易行为对市场波动的冲击存在显著的非对称特征,正的交易量冲击(交易量放量冲击)比同等程度的负交易量冲击(交易量缩量冲击)对市场波动的影响更大.     

In silico correlation of enantioselectivity for the TADDOL catalyzed asymmetric hetero-Diels-Alder reaction

The reverse-docking of a TADDOL organocatalyst to rigid transition state models of catalyst-free reactions (TS-models) for an asymmetric hetero-Diels-Alder reaction is described. In previous reports, reverse-docking of similar organocatalysts to rigid TS-models showed promise for generating transition state models for the catalyzed reaction, and revealed clear energetic trends favoring the experimentally preferred product enantiomers. Although results indicated a mode of catalysis consistent with experimental data, relative docking energies between TS-model enantiomers were too great to allow for in silico correlation to experimentally observed enantiomeric excesses (ee). Several changes were made to the reverse-docking algorithm, EM-Dock, allowing for the first reported correlation to experimentally reported ee values based solely on reverse-docking and molecular mechanics energies.     

Protecting‐Group‐Free Total Synthesis and Biological Investigation of Cabucine Oxindole A†

Owing to their challenging structures and promising biological profiles, spirooxindole alkaloids have long attracted much attention from the synthetic community. Herein, we wish to describe a concise, protecting‐group‐free total synthesis of cabucine oxindole A, a putative natural spirooxindole alkaloid and a possible biosynthetic congener of cabucine and palmirine. Key transformations of our approach include a one‐step, organocatalytic and enantioselective construction of the spiro[pyrrolidine‐3,3’‐oxindole] moiety and a Korte rearrangement to furnish the final dihydropyran motif. Biological investigation of 1 and its synthetic intermediates revealed lactone 2 as a mild MOLT‐4 and MCF7 cell line inhibitor.     

Increasing the cold atom density in an integrating spherical cavity

A novel method of angled incidence for diffuse laser cooling of ⁸⁷Rb is presented to improve the distribution of cold atom density in an integrating sphere. The angled injection scheme could cool more atoms in the middle of the sphere compared to the previous normal injection scheme. The loading time of the cold atoms for the angled injection scheme is twice as that of the normal injection scheme. The SNR and the contrast of the detected signal would be improved in the angled injection scheme.     

Diastereoselective conjugate addition of organocuprates to N-[4-(Dibenzylaminobutenoyl)]oxazolidinone. Synthesis of chiral β-substituted γ-aminoacids

The first conjugate addition reaction of organocuprates to N-enoyl oxazolidinone where a γ-nitrogen atom is present into α,β-unsaturated system is described. The reaction gave syn-products in moderate yields and high diastereomeric ratios. The removal of chiral oxazolidinone moiety and N-deprotection of amino group furnished chiral β-substituted γ -amino acids.     

Total synthesis and determination of the absolute configuration of paralemnolin C and biological studies of eremophilane derivatives

The first asymmetric total synthesis of paralemnolin C was achieved. The absolute configuration at C11 of this natural product was determined from the X-ray crystallographic analysis of the epoxide derivative. In addition, biological studies of eremophilane derivatives including paralemnolin C and sagittacin E were carried out.