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Development of new radical reactions in aqueous media

水介质中新自由基反应的发展

基本信息

批准号：
12305058
负责人：
OSHIMA Koichiro
金额：
$ 28.48万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

Triethylborane-induced hydrometalation of alkynes proceeds in an anti manner to afford the corresponding (Z)-alkenylmetal compounds stereoselectively, where dichloroindium hydride would play a key role. A variety of functional groups including hydroxy, carbonyl, and carboxy groups were tolerant under the reaction conditions. Following iodolysis and cross-coupling reaction of the (Z)-alkenylmetal species show the usefulness of this strategy.An allylgallium reagent is found to be effective for radical allylation of α-iodo or α-bromo carbonyl compounds. Treatment of benzyl bromoacetate with allylgallium, prepared from allylmagnesium chloride and gallium trichloride, in the presence of triethylborane in THF provided benzyl 4-pentenoate in good yield. The addition of water as a cosolvent improved the yields of allylated products. It was revealed that the allylgallium species resists immediate decomposition on exposure to water.Bis (cyclopentadienyl) zirconium chloride hydride (Schwartz reagent) proved to be an efficient radical chain carrier for the reduction of organic halides in the presence of triethylborane. Reductive radical cyclization of halo acetals with Cp_2Zr(H)Cl generated in situ from Cp_2ZrCl_2 and sodium bis (2-methoxyethoxy) aluminium hydride (Red-Al) provided the cyclized products in good to excellent yields. Reaction employing a catalytic amount of Cp_2ZrCl_2 combined with Red-Al and triethylborane was also successful.

三乙基硼烷诱导的炔烃氢金属化反应以相反的方式立体选择性地生成相应的(Z)-烯基金属化合物，其中二氯铟氢化物起着关键作用。在该反应条件下，羟基、羰基和羧基等多种官能团都具有耐受性。随后的碘解和(Z)-烯基金属物种的交叉偶联反应表明了这一策略的有效性。烯丙基镓试剂被发现对α-碘或α-溴代羰基化合物的自由基烯丙基化反应是有效的。在三乙基硼烷存在下，由烯丙基氯化镁和三氯化镓合成的烯丙基镓与溴乙酸苄酯在四氢呋喃中反应，得到了高产率的4-戊烯酸苄酯。加入水作为助溶剂提高了烯丙化产物的产率。双环戊二烯基氯化锆(Schwartz试剂)是有机卤化物在三乙基硼烷存在下还原的有效自由基链载体。由Cp_2ZrCl2和双(2-甲氧基乙氧基)铝氢化钠(Red-Al)原位生成的Cp_2Zr(H)Cl与卤代缩醛的还原自由基环化反应以较好的产率得到了环化产物。Cp_2ZrCl2与红铝和三乙基硼烷的催化反应也是成功的。