手性咪唑啉的合成及应用研究

以1,2-二苯基乙二胺和邻羟基苯乙酸以及脯氨酸为原料,设计并合成了咪唑啉-酚,四氢吡咯-咪唑啉两类手性催化剂,初步研究了它们在催化不对称Michael加成反应中的催化活性.     

手性咪唑啉的合成及应用研究

以1,2-二苯基乙二胺和邻羟基苯乙酸以及脯氨酸为原料,设计并合成了咪唑啉-酚,四氢吡咯-咪唑啉两类手性催化剂,初步研究了它们在催化不对称Michael加成反应中的催化活性．     

用亲电加成反应的机理预测烯烃加成反应产物研究

以亲电加成反应机理为基础,将电子诱导效应和碳正离子稳定性两方面因素相结合,预测不对称烯烃的亲电加成产物。给出了判断亲电加成反应中间体碳正离子稳定性的方法和预测亲电加成反应主要产物的依据。     

新手性吡啶类配体的合成及其不对称诱导性能研究

以2,6-二甲基吡啶和2,6-二溴吡啶为原料,经锂试剂分别与光学活性的樟脑、薄荷酮和3-甲酰基蒎烷反应合成了4个新的手性吡啶类化合物。测定了它们在苯甲醛和二乙基锌加成反应中的不对称诱导性能。     

双官能团离子液体[Promim]^＋[CF3CO2]^-支撑不对称Aldol反应的密度泛函理论研究

用密度泛函理论B3LYP方法对双官能团离子液体[Promim]+[CF3CO2]-支撑丙酮与邻-硝基苯甲醛不对称aldol反应进行了研究.结果表明,该离子液体的脯胺酸和咪唑基团一起对反应产生催化作用.整个反应包括:丙酮的羰基与脯胺酸基团的胺基间的亲核加成反应,咪唑2-位氢参与的脱水反应生成亚胺IM1-2,丙酮甲基脱氢反应生成烯胺I M1-3,苯甲醛与烯胺的亲核加成反应,水加成反应和催化剂再生反应.第一步骤是速率控制步骤,产物羟基位碳原子的手性在苯甲醛与烯胺的亲核加成反应中产生.另外,在咪唑环2-位氢参与的脱水反应中生成的水分子辅助丙酮甲基脱去α-氢生成烯胺.苯甲醛邻位吸电子基团能降低醛基碳原子的电子密度,增强醛基碳原子的亲电性,从而增强反应物活性.离子液体[Promi m]+[CF3CO2]-产生的溶剂化效应使反应势垒降低(除开催化剂再生步骤).     

新手性吡啶类配体的合成及其不对称诱导性能研究

以２，６－二甲基吡啶和２，６－二溴吡啶为原料，经锂试剂分别与光学活性的樟脑、薄荷酮和３－甲酰基蒎烷反应合成了４个新的手性吡啶类化合物。测定了它们在苯甲醛和二乙基锌加成反应中的不对称诱导性能。     

调控左右不对称模式建成的分子机制研究进展

器官左右不对称模式发生的内在分子调控机制极其复杂。综述了近年来4种经典分子信号途径在调控组织器官不对称发育中的作用及分子调控机制。     

羟脯氨酸衍生的双功能催化剂的合成与应用

以(L)羟脯氨酸为初始原料,设计合成了分别含有硫脲、磺酰胺和方酰胺等官能团的三类有机小分子催化剂,并将其用于醛与N-Boc亚胺的不对称anti-Mannich反应,分别比较了它们的催化活性.     

2-乙酰基环己酮的合成与表征

研究了2-乙酰基环己酮的合成方法，结果表明，环己酮和吗啡啉以有机溶剂甲苯为共沸剂，以对甲笨磺酸为催化剂，进行缩合反应生成烯胺，然后加入缚酸剂三乙胺，滴加乙酰氯和有机溶剂的混合物，烯胺与乙酰氯发生亲核加成反应，生成亚胺正离子，最后加入浓盐酸对亚胺正离子进行水解，可生成研究产物2-乙酰基环己酮。产物结构经红外光谱、核磁共振氢谱分析验证与目标化合物的结构一致。     

拟除虫菊酯合成中的不对称环丙烷化研究进展

拟除虫菊酯是一类重要的环境友好杀虫剂,手性金属配合物催化的不对称环丙烷化反应是合成拟除虫菊酯的重要途径。总结了近10年来不对称环丙烷化反应在拟除虫菊酯合成中的研究进展,并对其发展趋势进行了展望。     

Dynamic control of chiral space in a catalytic asymmetric reaction using a molecular motor

Enzymes and synthetic chiral catalysts have found widespread application to produce single enantiomers, but in situ switching of the chiral preference of a catalytic system is very difficult to achieve. Here, we report on a light-driven molecular motor with integrated catalytic functions in which the stepwise change in configuration during a 360° unidirectional rotary cycle governs the catalyst performance both with respect to activity and absolute stereocontrol in an asymmetric transformation. During one full rotary cycle, catalysts are formed that provide either racemic (R,S) or preferentially the R or the S enantiomer of the chiral product of a conjugate addition reaction. This catalytic system demonstrates how different molecular tasks can be performed in a sequential manner, with the sequence controlled by the directionality of a rotary cycle.     

Current status of asymmetric synthesis

In the last 30 years the subject of asymmetric synthesis has grown from a little studied academic niche in organic chemistry to an intensely investigated field of commercial importance and heightened general interest. Impressive advances have been made in several areas, notably catalytic asymmetric homogeneous hydrogenation, catalytic asymmetric epoxidation of allyl alcohols and stereochemical control of carbon-carbon bond-forming reactions. Asymmetric synthesis must now be deliberately considered along with other available methods as a practical strategy for the synthesis of any chiral compound.     

Asymmetric catalysis of the transannular Diels-Alder reaction

Transannular chemical reactions are unparalleled in their ability to generate high degrees of stereochemical and architectural complexity in a single transformation. However, the successful application of this approach in synthesis depends on the ability to predict and control the outcome of the transannular reaction. Use of a chiral catalyst in this context represents an attractive, yet unused, strategy. This report describes a catalytic, asymmetric transannnular Diels-Alder (TADA) reaction that affords polycyclic products in high enantiomeric excess. This catalyst system can also alter the inherent diastereoselectivity of cyclizations with substrates containing chiral centers. Additionally, the catalytic enantioselective TADA has been used as the key step in a total synthesis of the sesquiterpene 11,12-diacetoxydrimane; this route may provide a general approach to the polycyclic carbon framework shared by many terpene natural products.     

通用小型汽油机尾气排放NO的净化

采用Pt-Rh催化器净化方法,并着重探讨了以降低NO排放为主的Pt-Rh催化器性能、排放温度、NO还原催化的性能和转化效率控制等问题。试验研究了Pt-Rh催化器的转化效果、其间的相互影响和作用,并提出相应的排放建议。结果表明:当贵金属Rh的加入量为30g时,Pt-Rh催化器可有效降低小型汽油机的NO排放量,最高转化效率达到48%,同时对HC、CO的排放也有一定的降解作用。     

开孔农用隐蔽式通信电缆屏蔽效应分析(英文)

以农用隐蔽式信号电缆的开孔屏蔽壳体为研究对象,应用线性边界元法计算了屏蔽体上开有不同对称/非对称孔型时对屏蔽效能的影响。根据工程实例计算表明:对于双芯屏蔽电缆,当孔深较浅时屏蔽电缆的耦合电容影响不大,随着孔洞深度的增加,对称/非对称劈形孔耦合电容变化幅度最小;而不同形状孔洞的宽窄对耦合电容影响不太明显。     

UV dosage levels in summer: increased risk of ozone loss from convectively injected water vapor

The observed presence of water vapor convectively injected deep into the stratosphere over the United States can fundamentally change the catalytic chlorine/bromine free-radical chemistry of the lower stratosphere by shifting total available inorganic chlorine into the catalytically active free-radical form, ClO. This chemical shift markedly affects total ozone loss rates and makes the catalytic system extraordinarily sensitive to convective injection into the mid-latitude lower stratosphere in summer. Were the intensity and frequency of convective injection to increase as a result of climate forcing by the continued addition of CO(2) and CH(4) to the atmosphere, increased risk of ozone loss and associated increases in ultraviolet dosage would follow.     

H_2O_2清洗对蔬菜中农药去除效果及机制的研究

为了提高蔬菜在清洗过程中的农药去除率,利用低浓度的H_2O_2清洗不同类型的蔬菜。结果表明,在酸性(p H=4.0)条件下,含铁量较高的蔬菜能较明显提高H_2O_2氧化去除敌敌畏的效率。通过叔丁醇试验发现,敌敌畏去除率的提高主要原因可能是由于蔬菜基质自身的Fe~(2+)或Fe~(3+)催化H_2O_2有效地产生了高活性的羟基自由基。试验进一步探讨了H_2O_2清洗几种典型的有机磷、有机氯和氨基甲酸酯类农药的降解,结果表明该体系针对不同类型的农药都具有降解效率。     

信息不对称与茶叶营销

在茶叶市场营销中存在着消费者与经销商之间信息不对称的现象。从茶叶市场营销的实际出发，详细阐述了信息经济学和不对称信息理论及其在茶叶营销中的市场表现，并在此基础上分析了信息不对称条件下的茶叶营销困境，提出了克服茶叶市场营销信息不对称对市场不良影响的对策。