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

(1)三（苯基硒）硼烷或三（甲基硒）硼烷加入末端三键，形成乙烯基硒化物。这个加成反应是由氧引起的，并通过自由基过程进行。用^1H-和^<11>B-NMR谱研究了反应机理。(2)该反应适用于含氮、氧或硫原子的炔的环化反应。双键中间的乙烯基自由基的分子内环闭合优先通过5-外环模式进行，氮、氧或硫杂环是非对映选择性给出。产量很高。(3)四氢呋喃和四氢吡喃衍生物在氯化锌或氯化锡的存在下，三（苯硒）硼烷发生C-O键裂解，得到了产率很高的-苯硒醇。(4)用Lewis酸处理二硒缩醛生成-硒碳正离子。烯烃-硒碳正离子发生了内选择性闭环。

(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.