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

金属表面覆盖着薄而紧密结合的氧化层。为了在有机合成中使用这类金属，必须开发去除氧化层的有效方法。Me_3SiCl处理能有效去除金属锰表面的金属氧化物层，PbCl_2的催化量对金属锰具有很好的活化作用。用活性金属锰进行重整基型反应和羰基化合物烯丙基化反应。此外，在锰还原体系下，烷基碘化物、α、β -不饱和腈（或酯）和羰基化合物的三组分偶联反应均获得了优异的产率。虽然PbCl_2的作用尚不清楚，但加入一定量的盐对于还原烷基碘化物是必不可少的。在烯丙基丙烯酸酯上以1,4方式加入烷基自由基得到α -烯丙基羰基取代的烷基自由基，经单电子还原生成烯丙基硅基缩醛。在DMF和THF中用烷基碘化物和锰- pbcl_2 - me_3sicl体系进行了1,4加成和连续的Ireland-Claisen重排。产生的双键具有E型几何形状，正如Ireland-Claisen重排所预期的那样。上述顺序反应是通过区分烷基和α -烷氧羰基取代的芳基自由基的中等锰还原体系实现的。以下的立体选择有机转化也发展了与低价铬。(1)在温和条件下，以二氯甲基硼酯、CrCl_2和LiI为原料，采用双铬试剂，立体选择性地合成了合成有用的(E) -1-烯基硼酯。(2)根据镍（II）盐的催化量对先前报道的炔基和烯基铬试剂的制备方法进行了检查，建立了铬试剂制备的标准方案。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