左旋丙叉甘油醇合成方法的改进

左旋丙叉甘油醇合成方法的改进;L-丝氨酸;合成;左旋丙叉甘油醇;二甲氧基丙烷     

环丙烷衍生物的简便合成

报道了4-甲氧基．2-溴代丁烯内酯(4)与几种醇通过串联的双。Michael加成及分子内的亲核取代反应，简便地得到了环丙烷类化合物8。经元素分析、IR、^1HNMR、^13CNMR和MS对目标产物进行了结构表征，其中8a通过单晶培养和x射线晶体测定，确定了它的立体结构。     

贫电子环丙烷衍生物的化学

综述了贫电子环丙烷衍生物——顺式-1,2-二取代-6,6-二烷基-5,7-二氧螺- [2,5]-4,8辛二酮与含氧、氮、硫等亲核试剂反应的研究进展。     

手性螺-环丙烷双内酯化合物的合成与结构

本文进一步研究了5-(l-孟氧基)-3-溴-2(5H)-呋喃酮(1)与氧的亲核试剂,如二苯甲醇、苯甲醇、α-甲基苯甲醇、薄荷醇、冰片醇发生新颖的串联不对称双Michael加成/分子内亲核取代反应,合成了一般方法难以合成的含有多个手性中心的螺[1-溴-4-l-孟氧基-5-氧杂-6-氧代双环[3.1.0]己烷-2,3'-(4'-亲核基-5'-孟氧基丁内酯)](4a-4e)。通过元素分析,IR,UV,^1HNMR,^1^3CNMR,MS,[α]~D^2^0波谱分析数据以及X四圆衍射确定了4a-4e的化学结构和绝对构型。     

自由基正离子催化的Diels-Alder环加成反应研究进展

本文回顾了分子间Diels-Alder反应的定义和类型,详细总结了自由基正离子催化的Diels-Alder环加成反应方式,包括铵基阳离子、电化学、三价铁和光催化等方法,对不同催化体系的优缺点进行了说明。同时总结了自由基正离子Diels-Alder环加成反应的现状、面临的挑战,以及未来的发展趋势。     

2-甲基氮杂环丙烷与CO_2的环加成反应

采用碱金属卤化物和季铵盐作为催化剂在温和条件下催化2-甲基氮杂环丙烷的CO2环加成反应,得到区域选择性的4-甲基-2-噁唑烷酮.实验结果表明,该合成路线具有反应条件温和、收率高、区域选择性好、操作简单、对环境安全友好等特点.     

手性螺-环丙烷化合物中手性辅基的区域性转换反应的研究

通过串联的不对称双Michael加成/分子内亲取代反应,一举得到了具有四个新手性中心的螺环/环丙烯类化合物(4).4在丙酮-5%HCl溶液中50℃下发生区域选择性单水解转换反应,得到螺[1-溴-4-羟基-5-氧杂-6-氧代双环[3.3.0]已-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](5),化学产率53%～69%,光学纯度d.e≥98%.4在甲醇/TsOH催化下,实现了区域选择性单醇解转换反应,得到螺[1-溴-4-甲氧基-5-氧杂-6-氧代双环[3.1.0]已烷-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](6),化学产率50%～78%,光学纯度d.e.≥98%.经元素分析,[α]D^20,UV,IR,1^HNMR,13^CNMR,MS以及X射线四圆衍射测定,确认了它们的化学结构。     

一种多取代硝基环丙烷的开环反应研究

以一种多取代硝基环丙烷为底物,研究其在不同条件下的开环反应.以苄胺为亲核试剂时,底物发生开环生成烯胺化合物,对此反应机理进行了分析.研究了底物的还原开环反应：1）在Pd/C的催化氢化下,底物发生开环并消除硝基,得到烷基取代丙二酸二甲酯衍生物;2）在浓盐酸存在下用锌粉还原底物,得到五元环内酰胺.     

手性螺-环丙烷化合物中手性辅基的区域性转换反应的研究

通过串联的不对称双Michael加成/分子内亲取代反应,一举得到了具有四个新手性中心的螺环/环丙烯类化合物(4).4在丙酮-5%HCl溶液中50℃下发生区域选择性单水解转换反应,得到螺[1-溴-4-羟基-5-氧杂-6-氧代双环[3.3.0]已-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](5),化学产率53%～69%,光学纯度d.e≥98%.4在甲醇/TsOH催化下,实现了区域选择性单醇解转换反应,得到螺[1-溴-4-甲氧基-5-氧杂-6-氧代双环[3.1.0]已烷-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](6),化学产率50%～78%,光学纯度d.e.≥98%.经元素分析,[α]D^20,UV,IR,1^HNMR,13^CNMR,MS以及X射线四圆衍射测定,确认了它们的化学结构。     

乙烯基环丙烷自由基开环聚合研究进展

乙烯基环丙烷（VCP）是重要的环状单体之一,具有典型的高张力三元环结构,在自由基聚合条件下,能够发生1,5-开环及多种环化反应,生成含有2-戊烯等重复单元的复杂聚合物。聚乙烯基环丙烷（PVCP）具有较小的体积收缩率,是重要的修复材料,在临床等多个领域具有潜在应用价值。本文结合近年来的重要成果,梳理了VCP单体自由基开环聚合的发展过程,重点介绍单体结构设计、聚合物结构控制策略以及结构和材料性能之间的关系。最后,对VCP自由基开环聚合研究领域仍然存在的问题和解决方法进行了总结和展望。     

Block Copolymer Based Molecular Motor

We propose a model of molecular motor based on diblock copolymer strongly adsorbed on a patterned surface. One of the blocks of the copolymer is modeled as field responsive. It is shown that time‐periodic collapse‐readsorption of the responsive block leads to the directed motion (reptation) of the molecule along the “track” provided by the surface pattern. Both the Langevin dynamics (LD) technique of computer simulation for the bead‐spring model and numerical solution of the Newton equations of a simplified (toy) model of the copolymer are used. The physical reason of directionality of the motion is shown to be an anisotropy of the friction of the molecule with the surface.

     

Orthogonally Self‐Assembled Multifunctional Block Copolymers

We report the synthesis of telechelic poly(norbornene) and poly(cyclooctene) homopolymers by ring‐opening metathesis polymerization (ROMP) and their subsequent functionalization and block copolymer formation based on noncovalent interactions. Whereas all the poly(norbornene)s contain either a metal complex or a hydrogen‐bonding moiety along the polymer side‐chains, together with a single hydrogen‐bonding‐based molecular recognition moiety at one terminal end of the polymer chain. These homopolymers allow for the formation of side‐chain‐functionalized AB and ABA block copolymers through self‐assembly. The orthogonal natures of all side‐ and main‐chain self‐assembly events were demonstrated by ¹H NMR spectroscopy and isothermal titration calorimetry. The resulting fully functionalized block copolymers are the first copolymers combining both side‐ and main‐chain self‐assembly, thereby providing a high degree of control over copolymer functionalization and architecture and bringing synthetic materials one step closer to the dynamic self‐assembly structures found in nature.     

Synthesis,Crystal Structure and Magnetism Characterization of Two Coordination Polymers based on Ni(2‐mpac)2(H2O)2 as Molecular Building Block

Taking Ni(2‐mpac)₂(H₂O)₂ as molecular building block, two novel coordination polymers with the formula of [Ni(2‐mpac)₂(4,4′‐bpy)·(4,4′‐bpy)]_n ( 1 ) and [Ni(2‐mpac)₂(py)·4H₂O]_n ( 2 ) (2‐mpac = 5‐methyl‐2‐pyrazinecarboxylic acid; 4,4′‐bpy = 4,4′‐bipyridine; py = pyrazine) have been synthesized and structurally characterized by X‐ray single crystal diffraction method. In addition, elemental analysis, IR and magnetism characterization are presented.     

5‐Formyluracil as a Multifunctional Building Block in Biosensor Designs

In organisms 5‐formyluracil (5fU), which is known as a vital natural nucleobase, is widely present. Despite the recent development of sensor designs for organic fluorescent molecules for selective targeting applications, biocompatible and easily operated probe designs that are based on natural nucleobase modifications have rarely been reported. Here, we introduce the idea of 5fU as a multifunctional building block to facilitate the design and synthetic development of biosensors. The azide group was derived from the sugar of a nucleoside, which can be further used in the selective binding of cells or organelles through click chemistry with alkynyl‐modified targeting groups. The aldehyde group of 5fU can react with different chemicals to generate environmentally sensitive nucleobases that have obvious characteristics, which precious reactants cannot achieve for selective fluorogenic switch‐on detection of a specific target. We first synthesized 5fU analogues that had aggregation‐induced emission properties, and then we used triphenylphosphonium as a mitochondria‐targeting group to selectively image mitochondria in cancer cells and mouse embryonic stem cells. Additionally, the reagents exhibit a high selectivity for reaction with 5fU, which means that the method can also be used for the detection of 5fU. Combining the two characteristics, the idea of 5fU as a multifunctional building block in biosensor designs may potentially be applicable in 5fU site‐specific microenvironment detection in future research.     

Multifunctional Thermally Reversible Nanostructured Thermosetting Materials Based on Block Copolymers Dispersed Liquid Crystal

Thermally reversible nanostructured thermosetting materials are prepared for the first time by modification of an epoxy resin with 5 wt.‐% of an amphiphilic polystyrene‐block‐poly(ethylene oxide) block copolymer (PSEO) and 30 wt.‐% of a low‐molecular‐weight liquid crystal, 4′‐(hexyl)‐4‐biphenylcarbonitrile (HBC). The epoxy system modified with 5 wt.‐% PSEO amphiphilic copolymer self‐assembles into spherical microdomains with a size distribution between 32 and 45 nm in diameter. Under the same conditions, the modification of an epoxy system with 5 wt.‐% PSEO and 30 wt.‐% HBC leads to a micro‐phase separated PS‐rich domains embedded in a HBC phase. The morphology of this nanostructured thermosetting system consists in a higher amount of spherical microdomains of PSEO/HBC with the size distribution between 40 and 75 nm in diameter. This implies that the separation of the PS‐rich phase provokes the separation of the liquid crystal and allows one to obtain a novel thermally switchable smart material.

     

Polyoxometalates as Inorganic Building Blocks of Multifunctional Molecular Materials

The use of polyoxometalates (pOM's) as inorganic component in the synthesis of new molecular hybrid materials is presented. Here we show that the combination of organic molecules of the tetrathiafulvalene (TTF) type or perylene (per) with POM's yields new radical salts with unprecedented structures that present interesting magnetic and/or electrical properties or coexistence of both. The first true metallic radical salt containing a POM has been prepared and characterized. We also describe the recent results obtained by combining magnetic POM's with the organometallic cation decamethylferrocene.     

由D-Erythorbic Acid合成新的多官能团C4手性筑块

手性C4筑块是合成许多天然产物 Leukotrienes, Pyrrolizidine alkaloids及前列腺素A2等的重要合成子[1～3]. 然而到目前为止, 手性C4筑块只有从少数几种手性源如酒石酸, L-苏糖, D-赤藓糖等中才能得到[2～7]. 我们在以D-erythorbic acid为原料合成新型手性配体的过程中[8～10], 发现了一种简便获得选择性保护的多官能团手性C4筑块(化合物4, 5)的新途径(Scheme 1).     

A Uniqueness Theorem of Molecular Recognition

Phrased in terms of electron density deformations due to molecular interactions, an optimality condition, and the fundamental holographic properties of molecular electron densities, it is shown that molecular recognition is necessarily unique. A simple proof is given and the connections of this result with the Duality Principle of Molecular Recognition and related Selectivity Measures for molecular recognition are discussed.     

Modular Toolkit of Multifunctional Block Copoly(2-oxazoline)s for the Synthesis of Nanoparticles

Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.     

Orthogonally Incorporating Dual-Fluorescence Control into Gated Photochromism for Multifunctional Molecular Switching

Gated photochromism is of interest for the operation and control of modern high-tech optofunctional materials. For further advancing this topic towards the achievement of multifunctional molecular switching, however, it remains a great challenge to incorporate multiple fluorescence regulation into gated photochromism in one unimolecular system. Herein, it is reported that a dithienylethene derivative DTEN with a Schiff base connection can be facilely synthesized by one-step coupling, and it enabled distinct color and spectral changes upon different stimuli, including ultraviolet, visible light, Ni²⁺, and Al³⁺. Relying on hydrazine and hydroxy units in this molecule, compound DTEN exhibited novel Ni²⁺-locked photochromic characteristics originating from complexation of the compound with Ni²⁺ in a 2:1 stoichiometry. On the other hand, a 1:1 complexation between compound DTEN and Al³⁺ could allow both of the initial and photostationary states of DTEN to display fluorescent enhancement and a redshift, realizing a dual-fluorescence “turn-on” sensing of Al³⁺ by light. On this basis, it is argued that the switching of the coordination mode between DTEN and Ni²⁺ or Al³⁺ brings up the possibility of tunable photoswitching by multiple stimuli, which offers a novel way for future development of multifunctional switching materials with different input and output signals, as exemplified by the construction of a delicate molecular circuit.