二氧化碳: 一种同时提供亲核中心保护和亲电中心活化的试剂 XI:2-取代四氢噻唑的新合成方法

四氢噻唑和正丁基锂反应生成的N-锂代四氢噻唑(2)与二氧化碳作用生成N-羟酸锂盐3; 3然后在叔丁基锂作用下失去2-位质子形成相应的2-位碳阴离子4; 该碳阴离子和一系列亲电试剂反应, 并在酸性条件下除去保护基团得产物-2-取代四氢噻唑7. 在此过程中, 二氧化碳既是氨基的保护基团, 同时又活化了2-位亲电中心.此方法不需分离各步中间体, 产率中等.     

固态二乙炔拓扑聚合反应动力学的量子化学研究

利用协同反应模型和EHCO-ASED量子化学方法, 对固态二乙炔的拓扑聚合反应:MDA(Molecular diacetylenes)→PBT(Polybutatrienes)→PDA(Polydiacetylenes)的势能曲线进行了计算, 并对其轨道对称性以及能隙随反应坐标的变化进行了分析; 很好地解决了文献中用Woodward-Hoffmann轨道对称守恒原理对此反应进行分析时所遇到的问题, 指出了此反应是热允许的原因。     

Killing Pairs in Flat Space

In this paper the integrability conditions for Killing pairs in flat spaces are investigated and it is shown that only trivial Killing pairs exist.     

碳苷研究 V: 用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护

本文报道了一些取代苯酚的合成, 并探讨了用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护的问题. 利用苄基和甲基作为酚羟基的保护基, 对文献报道的切断醚键脱保护方法进行了评价. 找到了两种新体系能在更温和条件下切断醚键的方法, 指出了它们的适用条件. 实验结果符合硬软酸碱理论.     

Energy-Momentum and Equivalence Principle in Non-Riemannian Geometries

We introduce an energy-momentum density vector which is independent of the affine structure of the manifold and whose conservation is linked to observers. Integrating this quantity over time-like surfaces we can define Hamiltonian and momentum for the system which coincide with the corresponding ADM definitions for the case of irrotational Riemannian manifolds. As a consequence of our formalism, a Weak Equivalence Principle version for manifolds with torsion appears as the natural extension to non-Riemannian geometries from the Equivalence Principle of General Relativity.     

Conservation Laws and Symmetry Properties of a Class of Higher Order Theories of Gravity

We consider a class of fourth order theories of gravity with arbitrary matter fields arising from a diffeomorphism invariant Lagrangian density , with and the phenomenological representation of the nongravitational fields. We derive first the generalization of the Einstein pseudotensor and the von Freud superpotential. We then show, using the arbitrariness that is always present in the choice of pseudotensor and superpotential, that we can choose these superpotentials to have the same form as those for the Hilbert Lagrangian of general relativity (GR). In particular we may introduce the Moller superpotential of GR as associated with a double-index differential conservation law. Similarly, using the Moller superpotential we prove that we can choose the Komar vector of GR to construct a conserved quantity for isolated asymptotically flat systems. For the example R + R²theory we prove then, that the active mass is equal to the total energy (or inertial mass) of the system.     

(9-叔丁氧羰氨酰基氧甲基)芴-2-乙酰二苯甲胺树脂的制备及其在固相合成保护肽段中的应用

以芴为原料经羟甲基化, 乙酰化. 付氏反应和改良的Clemmensen还原等一系列反应合成了(9-叔丁氧羰氨酰基氧甲基)芴-2-乙酰二苯甲胺树脂. 它可作为固相合成保护肽段时的载体. 用这一新载体, 合成了大鼠转化生长因子α(γ-TGF-α)中的1至7的保护七肽片断段. 总收率可达50%.