Highly diastereoselective conjugate additions of monoorganocopper reagents to chiral imides

Stereoselective conjugate additions to chiral N-enoyl amides employing various monoorganocuprate reagents, Li[RCuI], are described. The presence of TMSI in the addition of Li[RCuI] in THF provided the highest stereoselectivities. Reversed major diastereomeric ratios were obtained employing Li[RCuI] in ether or conventional copper-promoted Grignard reagents. The results presented support the favored anti-s-cis conformation of the substrates using Li[RCuI]/TMSI in THF, while the copper-promoted Grignard reagents or the Li[RCuI] reagents in ether favor the opposite syn-s-cis conformation. Influence of lithium ions on the stereoselective conjugate addition of the monoorganocuprate reagent, Li[BuCuI], has been investigated and two different mechanistic pathways are presented. The results show that iodotrimethylsilane (TMSI) is crucial for the asymmetric conjugate addition of the copper reagent, but only in THF or when 12-crown-4 is used. The reaction is thought not to involve any halosilane in any critical steps in the organocopper mechanisms conducted in ether. The (CuI)₄(SMe₂)₃ complex precursor plays an instrumental role for the conjugate addition using monoorganocopper reagents.     

基于Iu_Flex的MSC Pool技术分析

本文简要介绍了MSC Pool技术的基本原理．分析了MSC Pool所用到的关键技术．重点讨论D接口信令的流量和MSC Pool的组网规划．指出了MSC Pool可能存在的安全隐患。     

An efficient method for preparing the sphingosine-1-phosphate receptor agonist, KRP203-phosphate

An efficient method for mono-phosphorylation of 2(KRP203)using cbz-protection,dibenzylphosphoryl chloride and TMSI affording 2-P(KRP203-P)was developed.We applied the present method to the synthesis of KRP203 phosphate analogs which were difficult to produce through tradition procedures.     

TMSI寻呼与选择性鉴权的使用

为了防止非法个人或团体通过监听无线路径上的信令交换而窃得移动用户真实的用户识别码（IMSI,International Mobi1e Subscriber Identification Number）或跟踪移动用户的位置,现在大多数交换机都开启了临时识别码（TMSI,Temporary Mobi1e Subscriber Identny）寻呼。而为了降低网络信令负荷,交换机可以将鉴权功能有选择性的打开。当TMSI寻呼和选择性鉴权同时打开时,有可能会造成用户的使用问题。这里主要讨论了TMSI寻呼和选择性鉴权的基本原理,并且根据在现网维护中遇到的用户投诉和河南部分交换机的设置分析二者同时打开时对网络的影响。     

GSM的安全性分析

文章介绍了GSM系统的安全体系,详细分析了系统中用户鉴权的过程及TMSI对该过程的影响,阐述了GSM的保密体制及其安全漏洞和可能受到的攻击.     

基于Iu_flex的MSC Pool技术分析

MSC池（MSCin Pool）是由3GPP规范定义的,能优化整个移动网络的组网。本文简要介绍了MSC Pool技术的基本原理及其组网特点,分析了MSC Pool所用到的关键技术（NRI路由机制和负荷分担）,重点讨论了核心网D接口信令的流量,根据MSC Pool的技术特点,提出了组网规划的前提条件和规划时需要注意的问题,最后总结了MSC Pool技术的特点,在结论部分给出了MSC Pool可能存在的安全隐患。     

TMSI-Promoted Diastereoselective Synthesis of 5-(1′-Hydroxy)-γ-butyrolactones

Trimethylsilyl iodide (TMSI) was found to be an efficient catalyst for the vinylogous Mukaiyama aldol reaction of 2-(trimethylsilyloxy)furan with various aldehydes with good diastereoselection. The reaction proceeds rapidly in CH₂Cl₂ affording the corresponding 5-(hydroxy(aryl)methyl)furan-2(5H)-ones in good yields. This method offers significant advantages such as efficiency, generality, and mild reaction conditions with shorter reaction time.

移动通信用户身份保密的增强方法

针对现有移动通信标准中无法完全实现用户身份保密这一问题,该文提出了分别基于公钥密码学和对称密钥密码学的两种改进措施,将用户的真实身份隐蔽在众多的用户标识里,使攻击者不能确切地得到用户身份的具体信息,明显增强了用户身份的保密性,并且分析比较了两种措施的性能.这些改进措施可以用于任何移动通信技术中.     

A novel TMSI-mediated synthesis of Hantzsch 1,4-dihydropyridines at ambient temperature

The synthesis of various substituted Hantzsch 1,4-dihydropyridines has been achieved using the classical Hantzsch procedure and modified Hantzsch conditions for the first time at room temperature in the presence of iodotrimethylsilane (TMSI) generated in situ in CH₃CN, in excellent yields.