New Development of Synthetic Reactions using Organoselenoboranes and Application to Synthesis of Pharmacologically Active Compounds

（1）三（苯硒基）硼烷或三（甲基硒基）硼烷加到末端三键上，形成乙烯基硒醚。该加成反应由氧引发，并通过自由基过程进行。通过^1H-NMR和1H-NMR研究了反应机理<11>。（2）该反应适用于含氮、含氧或含硫原子的烯炔的环化反应。乙烯基自由基中间体的双键的分子内闭环进行优先通过5-exo模式的环化和氮，氧或硫杂环的非对映选择性地给出。产量很高（3）在氯化锌或氯化锡存在下，三苯硒基硼烷与四氢呋喃和四氢吡喃的C-O键发生断裂反应，得到了高产率的ω-苯硒基醇。（4）用刘易斯酸处理二硒缩醛产生α-硒代碳阳离子。烯属α-硒代碳正离子进行内选择性闭环。

(1)Tris(phenylseleno)borane or tris(methylseleno)borane added to the terminal triple bonds and vinyl selenides were formed. This addition reaction was initiated by oxygen and proceeded by the radical process. The reaction mechanism was investigated by ^1H- and ^<11>B-NMR spectroscopy.(2)This reaction was applied to the cyclization reaction of enynes containing a nitrogen, an oxygign or a sulfur atom. The intramolecular ring closure of the vinyl radical intermediate to the double bond proceeded preferentially via 5-exo mode of cyclization and the nitrogen, oxygen or sulfur-heterocycles were diastereoselectively given. in good yields.(3)Tris(phenylseleno)borane underwent the C-O bond cleavage of the tetrahydrofuran and tetrahydropyran derivatives in the presence of zinc chloride or tin(IV)chloride to give omega-phenylseleno alcohols in excellent yields.(4)Treatment of diselenoacetals with a Lewis acid generated the alpha-seleno carbocations. The olefinic alpha-seleno carbocations underwent the endo-selective ring-closure.