Applications of Danishefsky’s dienes in asymmetric Oxo-Diels-Alder reactions

Applications of Danishefsky’s dienes in catalytic asymmetric hetero-Diels-Alder (AHDA) reactions or specifically, their asymmetric Oxo-Diels-Alder (AOxo-DA) reactions with appropriate dienophiles are highlighted in detail, including the preparation of catalysts with discussion from a mechanistic points of view. Danishefsky’s dienes are effective and useful compounds for the synthesis of optically active six-membered rings such as dihydropyrones, dihydropyridones and dihydropyrans. Due to the broad range of the overall subject, we have limited ourselves, to the recent developments in the utility of Danishefsky’s dienes in the reaction with carbonyl compounds (aldehydes, ketones and 1,2-dicarbonyl compounds) in asymmetric Oxo-Diels-Alder (AOxo-DA) reactions.     

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基于CN HCCB TBS的最新设计,用RELAP 5软件对失流事故(LOFA)和真空室内失冷事故(In-vessel LOCA)这两种假设基本事故进行了分析。结果表明,CN HCCB TBS在这两种事故工况下的安全性是有保证的,并且热工水力学瞬态分析能给出有关发生事故时 TBM 安全性相关性能的信息,从而提出了所需要的各种安全保护系统及其动作的时间。     

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基于中国氦冷固态增殖剂试验包层模块(CN HCCB TBM)的最新设计方案和ITER提供的中子学基准模型C-lite,采用国际通用的Monte Carlo粒子输运程序MCNP和欧洲活化程序FISPACT-2007对HCCB TBM及其辅助系统(统称为HCCB TBS)进行了详细的活化计算分析,得到并讨论了各结构部件的放射性、余热和接触剂量率结果.结果表明,停堆时HCCB TBM模块的总放射性和总余热分别为2.348×1016 Bq和5.826 kW.活化计算结果可以为TBS的安全分析、维护和放射性废物处置等提供数据基础和分析依据.     

An Efficient and Chemoselective Deprotection of tert-Butyldimethyl- silyl Protected Alcohols Using SnCl2.2H2O as Catalyst

An efficient and selective method for the deprotection of primary alcoholic tert-butyl-dimethylsilyl (TBS) ethers using SnC12“2H20 as catalyst is described. The reaction conditions allow primary alcoholic TBS ethers to be desilylated chemoselectively in the presence of phenolic TBS ethers, secondary and tertiary alcolholic TBS ethers, and the extensively used TBDPS-, acetyl-, benzyloxycarbonyl-, p-toluenesulfonyl- and benzyl protective groups.