Stereo- and regio-selectivity in the photosensitized dimerization of 1, 3-dimethylthymine in solution

The effects of reaction pathway and temperature on stereo- and regio-selectivity of photocycloaddition of 1, 3-dimethylthymine (DMT) which gives four cyclobutane type dimers in solution using acetone as the photosensitizer, are investigated by measuring the product distribution. It is demonstrated that the ground-state aggregation between DMT molecules mainly leads to (h-t)dimers, and the diffusion-controlled triplet dimerization is favorable to the formation of (h-h) dimers.     

聚乙二醇与PdCl_2催化端烯衍生物芳基化研究

研究了聚乙二醇与PdCl_2催化碘苯与端烯衍生物芳基化反应．实验证明聚乙二醇有显著催化作用，产品具有极好的区域和立体选择性．     

关于烯烃的亲电加成反应机理与立体选择性

烯烃的亲电加成反应机理一般认为有两种可能历程。一种是通过生成环状正离子中间体进行的，通过这样的历程进行的加成反应是反式加成。另一种是通过碳正离子中间体进行的，它所得到的产物无立体选择性。     

Copper Salt Catalyzed Amidations of Haloalkynes in the Synthesis of Ynamides

1 Introduction Ynamines [1-aminoalkynes, or N-alkynyl amines] have endured through two contrasting phases in the last four decades. First, they enjoyed a phase of synthetic eminence after the establishment of a practical synthesis in 1963. In the ensuing twenty years, ynamines became one of the most synthetically useful subgroups of alkynes utilized in countless creative work by many synthetic chemists. Reactivities of 1-aminoalkynes were thoroughly explored. However, unlike its close relativ…     

1，5－二甲基－6，8－二氧杂二环［3．2．1］辛烷的全合成

应用具有刚性结构的三环癸二烯酮，经高度立体选择性地引入官能团及逆第尔斯－阿尔德反应，合成了文题化合物（Ｆｒｏｎｔａｌｉｎ），包产率约２４．４％。     

Preferential hydrophobic interactions are responsible for a preference of D-amino acids in the aminoacylation of 5′-AMP with hydrophobic amino acids

We have studied the chemistry of aminoacyl AMP to model reactions at the 3 terminus of aminoacyl tRNA for the purpose of understanding the origin of protein synthesis. The present studies relate to the D, L preference in the esterification of 5-AMP. All N-acetyl amino acids we studied showed faster reaction of the D-isomer, with a generally decreasing preference for D-isomer as the hydrophobicity of the amino acid decreased. The -branched amino acids, Ile and Val, showed an extreme preference for D-isomer. Ac-Leu, the -branched amino acid, showed a slightly low D/L ratio relative to its hydrophobicity. The molecular basis for these preferences for D-isomer is understandable in the light of our previous studies and seems to be due to preferential hydrophobic interaction of the D-isomer with ademine. The preference for hydrophobic D-amino acids can be decreased by addition of an organic solvent to the reaction medium. Conversely, peptidylation with Ac-PhePhe shows a preference for the LL isomer over the DD isomer.     

联二萘酚衍生氨基吡啶类配体的合成

本文报道了2,6-二氨基吡啶与(S)-联二萘酚衍生的二溴化合物反应,合成了具有双氮杂环的氨基吡啶类配体.利用该配体与金属化合物络合,催化傅克反应,得到了较高的收率,但没有立体选择性.     

生物多聚体分子手性的起源

本文提出了手性分子聚合的合作理论，给出了各种手性参量的关系．证明生物前进化存在两种基本模式：一是大手性能量和小立体选择性的模式，其手性只能通过化学反应镜对称的自发破缺产生；二是小手性能量和大立体选择性的模式，其手性可通过弱作用产生     

7-甲氧基-5-烯-辛腈氧化物分子内环加成的立体选择性研究

用过渡状态理论和量子化学AM1方法，对7－甲氧基－5－烯－辛腈氧化物环加成反应机理进行了研究，结果表明，存在得到2种产物的平行反应，由于2个反应的速率常数比相关不大，得到反式产物和顺式产物比例为70∶30，与实验产率比值58∶42相比，结果基本一致。标题物立体专一选择性大小由活化焓和活化熵共同决定。