Dynamic Sterocontrol of Unstable Organic Reacitve Species

本研究在1998- 2001年期间取得了以下成果。1999年在札幌和2000年在筑波举行了研讨会。乙烯基硅烷的硅导向环化反应：四氢呋喃和四氢吡喃的立体选择性合成在酸催化下，羟基与烯属双键的硅导向立体选择性合成反应发生在分子内。环化通过羟基的立体定向合成加成进行。乙烯基硅烷（Z）-5-甲硅烷基-4-戊烯-1-醇的亚甲基链上带有取代基，可以顺利地进行酸催化环化反应，分别得到反式-2，5-、顺式-2，4-和反式-2，3-二取代四氢呋喃，具有中等至高的立体选择性.包括过渡金属在内的氧化还原体系诱导的新合成反应直接用于立体控制3。过渡金属催化合成反应中的立体控制4.前所未有的锰- ...更多信息 介导的反应：不稳定羰基叶立德的生成活性锰以双（氯甲基）醚为前体，生成不稳定羰基叶立德，用锰作还原剂，可以实现叶立德与缺电子亲偶极试剂的反应，而不需要还原剂直接还原亲偶极试剂.锰食源性物种：三烷基锰（II）酸盐试剂R_3MnLi与碘甲基硫醚反应生成硫甲基锰试剂，其中三烷基锰（II）酸盐试剂R_3MnLi起还原剂而非烷基化剂的作用。三烷基锰试剂的还原行为为直接生成一类新的试剂提供了一种途径，即具有结构多样性的硫代甲基锰试剂，以及生成的硫代甲基锰试剂与烯丙基溴、烯酮和β-环糊精的反应.自由基反应中的立体控制7.通过电子转移过程动态控制碳-碳键和碳-硅键形成反应中的反应途径

The following various successful results were ottained during this study between 1998-2001.Symposiums are held at Sapporo in 1999 and Tsukuba in 2000.1. Silicon-directed Cyclization of Vinylysilanes : Stereoselective Synthesis of Tetrahydrofurans and TetrahydropyransSilicon-directed stereoselective syn addition of hydroxy group to olefinic double bond occurs intramolecularly in an acid-catalyzed cyclization of vinylsilanes bearing hydroxy group. The cyclization proceeds by stereospecific syn addition of the hydroxy group. Vinylsilanes, (Z)-5-silyl-4-penten-1-ols bearing a substituent on the methylene tether, smoothly undergo the acid-catalyzed cyclization to give trans-2,5-, cis-2,4-, and trans-2,3-disubstituted tetrahydrofurans, respectively, with moderate to high stereoselectivity.2. New Synthetic Reactions induced by the Redox Systems including Transition Metals directed to Stereocontrol3. Stereocontrol in the Transition Metal-Catalyzed Synthetic Reactions4. Unprecedented Manganese- … More Mediated Reactions : Generation of Non-Stabilized Carbonyl YlidsActivated manganese generates nonstabilized carbonyl ylides from bis(chloromethyl) ethers as a precursor, and using this system with manganese as a reductant, the reactions of the ylides with electron-deficient dipolarophiles can be attained without the direct reduction of dipolarophiles by the reductant.5. Manganese Ate Species : Generation and Reactions with ElectrophilesTrialkylmanganese(II) ate reagents, "R_3MnLi" reacted with iodomethylsulfides to produce thiomethylmanganese reagents, where the manganate serves as a reductant not an alkylation agent. The reductive behavior of trialkylmanganese(II) ate reagents provides a protocol for the direct generation of a new class of reagents, thiomethylmanganese reagents with structural variety, and the generated thiomethylmanganese reagents reacted with allyl bromides, enones and aldehydes.6. Sterocontrol in the radical Reactions7. Dynamic control of the reaction pathways in the Formation Reactions of Carbon-Carbon Bonds and Carbon-Silicon Bonds via Electron Transfer Process Less