Development of Novel Activation Methods of Metals and its Applicatoin to Organic Synthesis.

金属表面覆盖着一层薄而紧密的氧化层。用Me_3SiCl处理金属锰表面可以有效地去除金属氧化物层，而催化量的PbCl_2则能使金属锰表面发生惊人的活化。用活化的金属锰进行Reformatsky型反应和羰基化合物的烯丙基化。此外，在锰还原体系中，碘代烷、α，β-不饱和腈（酯）和羰基化合物的三组分偶联反应也能以良好的产率进行。虽然PbCl_2的作用还不清楚，但加入催化量的PbCl_2盐对还原烷基碘是必不可少的。烷基自由基以1，4-方式与烯丙基丙烯酸酯加成得到α-烯丙氧羰基取代的烷基自由基，经单电子还原生成烯酮甲硅烷基缩醛。 关于我们 n和Me_3SiCl捕集。一号，在DMF和THF中，用碘代烷和锰-PbCl_2-Me_3SiCl体系进行4-加成和连续的Ireland-Claisen重排反应，生成的双键具有预期的E构型。上述顺序反应是用区分烷基和α-烷氧羰基的适度锰还原体系实现的。还已经用低价铬开发了以下立体选择性有机转化。(1)在温和的条件下，用二氯甲基硼酸酯衍生的偕二价铬试剂、CrCl_2和LiI，由醛经单碳扩链立体选择性地合成了（E）-1-烯基硼酸酯。(2)通过检查以前报道的炔基和烯基铬试剂的制备方法，在催化量的镍（II）盐方面，用于制备铬试剂的标准协议被建立。少

Metals are covered with thin but tightly bound oxide layrs on its surface. In order to employ such metals in organic synthesis, efficient methods for removing the oxide layrs should be developed.Metal-oxide layrs of manganese metal surface is effectively removed by treatment with Me_3SiCl, and a catalytic amount of PbCl_2 activates the manganese metal amazingly. Reformatsky-type reaction and allylation of carbonyl compounds are performed with the activated manganese metal. In sddition, three-component coupling reactions of alkyl iodides, alpha, beta-unsaturated nitriles (or esters), and carbonyl compounds are achieved in good to excellent yields with the manganese reducing system. Although the role of PbCl_2 is unclear, addition of a catalytic amount of the salt is essential for reducing the alkyl iodide.Addition of alkyl radicals to allylic acrylates in a 1,4-fashion gives alpha-allyloxycarbonyl-substituted alkyl radicals, which produce ketene silyl acetals after one-electron reductio … More n and trapping with Me_3SiCl. The 1,4-addition and successive Ireland-Claisen rearrangement take place by using alkyl iodides and the manganese-PbCl_2-Me_3SiCl system in DMF and THF.The double bond produced has E geometry as expected from the Ireland-Claisen rearrangement.The above sequential reactions are realized by using the moderate manganese reducing system which discriminate between alkyl and alpha-alkoxycarbonyl-substituted alyl radicals.The following stereoselective organic transformations have also been developed with low-valent chromium. (1) Synthetically useful (E) -1-alkenylboronic esters are prepared stereoselectively from aldehydes with olne-carbon extention by using a geminal dichromium reagent derived from a dichloromethylboronic ester, CrCl_2, and LiI under mild conditions. (2) By examination of the previously reported preparative methods of alkynyl- and alkenylchromium reagents in terms of a catalytic amount of nickel (II) salt, standard protocols for perparation of the chromium reagents are established. Less