discovered gem-hydrogenation of internal alkynes is a fundamentally new transformation, in which both H atoms of dihydrogen are transferred to the same C atom of a triple bond while the other position transforms into a discrete metal carbene complex. [Cp*RuCl]4 is presently the catalyst of choice: the resulting piano-stool ruthenium carbenes can engage a tethered alkene into either cyclopropanation or metathesis
最近唯一发现的内部炔烃的宝石氢化是一种全新的转化,其中二氢的两个 H 原子都转移到三键的同一个 C 原子上,而另一个位置转化为离散的金属卡宾配合物。[Cp*RuCl]4 是目前选择的催化剂:所得的钢琴凳式钌卡宾可以与系链烯烃结合进入环丙烷化或复分解,并且这种反应性中间体的典型例子与连接到钌中心的烯烃通过 X 射线衍射分离和表征。烯烃的取代模式决定了是否发生复分解或环丙烷化:使用性质大不相同的烯烃进行系统调查,并结合局部耦合簇理论水平的机理计算研究,可以对制备结果进行分类,并提出具有预测能力的直观模型。如果发生复分解,该模型将反应过程与双键的极化以及形成的二级卡宾配合物的稳定性联系起来。“氢化复分解”首次应用于 sinularones E 和 F 的全合成与这种解释一致,并允许这些海洋天然产物的拟议结构得到证实。在此合成过程中,发现宝石氢化也为 C-H 功能化提供了机会。而且,甲硅烷基化炔烃
KRIEF A.; LABOUREUR J. L.; DUMONT W., TETRAHEDRON LETT., 28,(1987) N 14, 1549-1552
作者:KRIEF A.、 LABOUREUR J. L.、 DUMONT W.
DOI:——
日期:——
Original syntheses of carbonyl compounds and gem-dihalocyclopropanes from β-hydroxyalkylselenides
作者:A. Krief、J.L. Laboureur、W. Dumont
DOI:10.1016/s0040-4039(01)81039-x
日期:1987.1
β-hydroxyalkylselenides possessing two alkyl substituents on the carbon bearing the selenenyl moiety react with dihalocarbenes generated from haloforms and thallous ethoxide or under phase transfer catalysis to produce ring enlarged ketones as the sole product in the first case, as the main product in the second. The reaction takes another course when the dihalocarbenes generated from haloforms and