Selective oxidation of polyfunctional 2-amino-1,3-propanediol derivatives

Oxidation of polyfunctional threo-(1S,2S)-2-amino-1,3-propanediol derivatives with a 717 anion-exchange resin-supported bromine has been investigated. The result showed that oxidized products were in close relationship with the substituents at nitrogen in the starting materials. Its primary and secondary amine derivatives were oxidized in the presence of Na(2)HPO(4) to give essentially a substituted chiral oxazoline or C(3)-O acylated product in high yield, while oxidation of its N,N-dimethyl derivative mainly gave a chiral N-methyl oxidation-formylation product. This selective oxidation was first observed in 2-amino-1,3-propanediol chemistry.     

Selective 1,3-cycloboronation of enantiopure 1,1,4,4-tetrasubstituted butanetetraols: versatile preparation,structural characterization,and properties of chiral cyclic boron-containing bifunctional Lewis acids

The selective cycloboronation of enantiopure 1,1,4,4-tetrasubstituted butanetetraols was investigated, and a general preparation of chiral cyclic boron-containing bifunctional Lewis acids was discovered. Compounds (2R,3R)- or (2S,3S)-1,1,4,4-tetrasubstituted butanetetraols were reacted with ArB(OH)₂ at reflux in toluene, or THF, or under solvent-free condition to furnish tricoordinated, chiral bicyclo[4.4.0]diboronic esters in high yield via selective 1,3-cycloboronation. Structural characterization and properties of the novel chiral boron compounds are also reported.     

玻璃纤维增强聚氨酯泡沫塑料的压缩力学性能研究

本文研究了两种不同密度的玻璃纤维增强聚氨酯泡沫塑料在准静态压缩下的力学性能。给出了与相应密度的普通泡沫塑料力学性能的比较，实验结果表明：两种增强泡沫塑料在压缩载荷作用下，具有不同于普通泡沫塑料的应力－应变特性，压缩模量和强度一般均有不同程度的提高，而且对相同纤维含量的增强泡沫塑料来说，密度较高的材料增强效果较好。     

1，1’－联－2－萘酚硼烷的辛可宁和麻黄碱衍生物的合成

１，１’－联－２－萘酚硼烷的辛可宁和麻黄碱衍生物的合成单自兴，孙杰，段标，杨洗，赵德杰（武汉大学化学系，武汉，４３００７２）关键词１，１’－联－２－萘酚，硼烷，辛可宁，麻黄碱，硼烷配合物，合成中国法分类号Ｏ６２７·３１ｌ，ｌ’一联一２一条酚在大环化学...     

Chiral Borate Esters in Asymmetric Synthesis. Part 2

Asymmetric catalytic activity of the chiral spiroborate esters 1 – 9 with a O₃BN framework (see Fig. 1) toward borane reduction of prochiral ketones was examined. In the presence of 0.1 equiv. of a chiral spiroborate ester, prochiral ketones were reduced by 0.6 equiv. of borane in THF to give (R)‐secondary alcohols in up to 92% ee and 98% isolated yields (Scheme 1). The stereoselectivity of the reductions depends on the constituents of the chiral spiroborate ester (Table 2) and the structure of the prochiral ketones (Table 1). The configuration of the products is independent of the chirality of the diol‐derived parts of the catalysts. A mechanism for the catalytic behavior of the chiral spiroborate esters (R,S)‐ 2 and (S,S)‐ 2 during the reduction is also suggested.     

碱存在下二烷基硼酸甲酯与氯仿的相转移反应研究

由烯烃经一氯硼烷甲硫醚（Ｈ２ＢＣｌ·ＳＭｅ２）硼氢化和甲醇解制得的二烷基硼酸甲酯６，在５０％ＮａＯＨ和相转移催化剂（ＴＥＢＡ）存在下与氯仿反应，继之氧化，获得了相应的二烷基酮１，二环烷基酮２和３以及脂环酮４．考查了各种参数对反应的影响．讨论了反应机理，为从烯烃出发合成各种类型的酮提供了一条简便新途径．     

低密度开孔泡沫材料力学模型的理论研究进展

开孔泡沫材料主要用于隔音、减振和填充方面，对其力学行为进行理论描述，探讨力学性能与密度及复杂微结构的关系具有十分重要的学术价值和工程意义．为了促进国内泡沫材料力学的发展和交流，文中对低密度开孔泡沫材料力学模型的研究历史进行了简要回顾，重点介绍了能较好地反映开孔泡沫材料真实胞体结构特点的十四面体胞体模型和随机胞体模型，并报道了近年来基于十四面体胞体模型和随机胞体模型研究低密度开孔泡沫材料力学行为的一些理论工作、同时，也对国内的一些相关研究情况进行了简要评述，指出了该领域今后的一些研究方向．     

聚氨酯泡沫塑料压缩杨氏模量的理论预测

通过微分法导出了泡沫塑料剪切模量和体积模量所满足的微分方程组，再利用联系泡沫塑料泊松比和孔隙比的Ｋｅｒｎｅｒ－Ｒｕｓｃｈ经验关系及泡沫塑料弹性常数间满足足的关系，在基体材料不可压缩的假设下，确定了泡沫塑料的杨氏模量。本文针对几种密度的泡沫塑料，分别对它们的杨氏模量进行了理论预测和实验测定，结果表明：理论预测的模量在较高密度下与实验符合的很好，在低密度下也给出相当好的近似值。此外，本文的结果同其他理     

Self‐Assembly of Amphiphilic Anthracene‐Functionalized β‐Cyclodextrin (CD‐AN) through Multi‐Micelle Aggregation

Multi‐micelle aggregation (MMA) mechanism is widely acknowledged to explicate large spherical micelles self‐assembly, but the process of MMA during self‐assembly is hard to observe. Herein, a novel kind of strong, regular microspheres fabricated from self‐assembly of amphiphilic anthracene‐functionalized β‐cyclodextrin (CD‐AN) via Cu(I)‐catalyzed azide‐alkyne click reactions is reported. The obtained CD‐AN amphiphiles can self‐assemble in water from primary core–shell micelles to secondary aggregates with the diameter changing from several tens nm to around 600–700 nm via MMA process according to the images of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy as well as the dynamic light scattering measurements, followed by further crosslinking through photo‐dimerization of anthracene. What merits special attention is that such photo‐crosslinked self‐assemblies are able to disaggregate reversibly into primary nanoparticles when changing the solution conditions, which is benefited from the designed regular structure of CD‐AN and the rigid ranging of anthracene during assembly, thus confirming the process of MMA.

     

代数函数域上的局部恢复码

假设C是有限域Fq上的[n,k]线性码,如果码字的每个坐标是其它至多r个坐标的函数,称C是(n,k,r)线性码,这里r是较小的数.本文在代数函数域上构造出了局部恢复码,它的码长不受字符集大小的限制,实际上,它的码长可以远远大于字符集的大小;并将此方法应用于广义Hermite函数域,得到了一类广义Hermite函数域上的局部恢复码.进一步地,通过构造子码的方式改进了广义Hermite函数域上的局部恢复码的最小距离的下界.