New Generation of Reactive 1,3-Dipole and Radical Reagents and Dynamic Sterocontrol

1.乙烯基硅烷的硅定向环化反应：四氢呋喃和四氢吡喃的立体选择性合成。在含羟基的乙烯基硅烷的酸催化环化反应中，分子内发生了羟基与烯烃双键的立体选择性合成反应。环化反应是通过羟基的立体定向合成进行的。乙烯基硅烷，(Z)-5-硅基-4-戊烯-1-醇，在亚甲基基醚上带有取代基，顺利地经酸催化环化，分别得到反式-2，5-，顺-2，4-和反式-2，3-二取代四氢呋喃，具有中等到高的立体选择性。含氨基的乙烯基硅烷的酸催化环化反应。吡咯烷的立体选择性合成在酸性催化剂的作用下，含氨基的乙烯基硅烷通过吸电子基团保护，顺利地环化成2-(硅甲基)吡咯烷。该环化反应用于2，n-二…的立体选择性合成更多取代吡咯烷(n=3-5)。史无前例的锰介体反应：生成不稳定的羰基叶立德活化的锰以双(氯甲基)醚为前驱体生成不稳定的羰基叶立德，使用该体系以锰为还原剂，叶立德与缺电子的亲偶极分子无需通过还原剂直接还原即可进行反应。三烷基锰酸盐试剂“R_3MnLi”与碘甲基硫化物反应生成硫甲基锰试剂，其中锰酸盐是一种还原剂，而不是烷基化试剂。三烷基锰酸盐试剂的还原行为为直接生成一类新的试剂--结构变化的硫甲基锰试剂提供了一种方案，生成的硫甲基锰试剂可以与烯丙基溴化物、烯酮和醛反应。烯丙基锡烷催化1，6-烯炔的自由基环化反应和以锡烯醇酸盐为自由基转移剂的新自由基反应。用铜(I)盐催化二硅烷在α，β-烯酮中引入硅基的新方法发现，在非质子性极性溶剂中，二硅烷与铜(I)盐的反应能有效地诱导硅-硅键的断裂生成硅基亲核试剂，并发现它与α，β-不饱和烯酮的1，4-加成反应以铜(I)盐的催化量进行。该反应被成功地应用于六甲基二硅烷，生成了迄今为止不易获得的三甲基硅基亲核试剂。首次系统地研究了过渡金属α-氰基碳负离子的碳键和氮键异构体的结构和反应活性。从结构分析、有机金属转化和机理研究的角度阐明了配体的立体化学对其反应活性和催化作用的重要贡献。通过选择合适的反应条件，实现了ω-乙酰基硅烯醇醚在五羰基钨催化环化反应中反应路径的动态控制，得到选择性的外环或内环产物。较少

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. Acid-Catalyzed Cyclization of Vinylsilanes Bearing an Amino Group. Stereoselective Synthesis of PyrrolidinesIn the presence of an acid catalyst, vinylsilanes bearing an amino group protected by an electron-withdrawing group were smoothly cyclized to 2-(silylmethyl)pyrrolidines. This cyclization was utilized for the stereoselective synthesis of 2,n-dis … More ubstituted pyrrolidines (n=3-5).3. Unprecedented Manganese-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.4. 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.5. Radical Cyclization of 1,6-Enynes Using Allylstannanes and New Radical Reactions Using Stannyl Enolates as Radical Transfer Agents6. New Method for Introduction of a Silyl Group into α,β-Enones Using a Disilane Catalyzed by a Copper(I) salt.The reaction of a disilane with a Cu(I) salt efficiently induces cleavage of the Si-Si bond to generate a silyl nucleophile in an aprotic polar solvent and its 1,4-addition to α,β-unsaturated enones smoothly proceeds with a catalytic amount of a Cu(I) salt were found. This reaction is successfully applied to hexamethyldisilane to generate a trimethylsilyl nucleophile, hitherto not easily accessible.7. The first systematic studies on the structure and reactivities of C-and N-bound isomers of transition metal a-cyanocarbanions have been carried out. Strong contribution of stereochemistry of ligands to their reactivities and catalysis has been clarified in view of structural analysis, organometallic transformations, and mechanistic investigations8. Dynamic control of the reaction pathways in the pentacarbonyltungsten catalyzed cyclization of ω-acetylenic silyl enol ethers is achieved giving either exo or endo cyclized product selectively by the appropriate choice of the reaction conditions. Less