Reaction Design of Medium-sized Ring Structure Based on the Working Hypothesis of Ethereal Oxonium Ylide Formation

基于以太氧叶立德形成工作假说的中型环结构反应设计

基本信息

批准号：
08455416
负责人：
OKU Akira
金额：
$ 4.93万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455416/
关键词：
carbene carbenoid oxonium ylide cyclic ether cyclic acetal cyclic orthoester ring-enlargement alkenyloxyketene 環状エーテル

项目摘要

The ambiphilicity of cerbene-type molecules can be inherited in the form of onium ylides. While ethereal oxonium ylides still continue to elude spectroscopic identification, their formations have been demonstrated indirectly by kinetic measurements, e.g., in the reaction of (biphenyl-4-yl) chlorocarbene with THF.On this basis, we designed novel ring-expansion reactions via bi-and tricyclic oxonium ylides for synthesis.Bicyclooxonium ylides formed in the Rh-catalyzed reaction of diazoketones tethered to five-to eight-membered cyclic ethers, where the tethering chains are one methylene units, underwent a novel three-carbon ring-enlargement reaction to form effectively the corresponding eight-to eleven-membered cyclic ketoethers, respectively. Diazoketones tethered to five-to eight-membered cyclic acetals, where the tethering chains are one or two methylene units, also underwent the similar enlargement reaction. Not only rhodium ketocarbenoids but also free carbenes such as alkylidenecarb … More enes bearing cyclic ethers or acetals behaved similarly to give cyclic dienol ethers. In all the reactions, key intermediates are bicyclooxonium ylides whose reactivity is controlled by the stability of charges and ring-strain.The reaction of bicyclic orthoester bearing a diazocarbonyl function tethered by one methylene unit produced a 9-membered polyoxygenated cyclic ether quantitatively. The enlargement efficiency is not attenuated when the tethering methylene chain is elongated from one to four. This indicates that the formation of tricyclooxonium ylides and their ring-expansion are highly favored by not only the enolate-stabilization but also the presence of three ethereal oxygen atoms in orthoesters which delocalize the positive charge of the ylides to facilitate the formation of ring-enlarged zwitterion (1, n-ambiphile) structure.In addition to the ring-expansion reaction, it was unveiled that oxonium ylides of cyclic ethers show an effective novel ring-opening rearrangement reaction leading to the formation of alkenyloxyketenes known as highly reactive transient species. Less

塞宾型分子的两亲性可以以鎓叶立德的形式遗传，虽然醚类氧鎓叶立德仍然无法通过光谱鉴定，但它们的形成已通过动力学测量间接证明，例如在（联苯-4-基）的反应中。）氯卡宾与THF。在此基础上，我们通过双环和三环氧鎓叶立德设计了新型扩环反应双环氧鎓叶立德是在铑催化的重氮酮与五至八元环醚（其中束缚链是一个亚甲基单元）的反应中形成的，经历了一种新颖的三碳环扩大反应，有效地形成了相应的八元环。分别连接至五至八元环状缩醛的十一元环状酮醚，其中连接。链是一个或两个亚甲基单元，不仅是铑酮类碳烯，而且带有环醚或缩醛的游离卡宾也进行了类似的放大反应，在所有反应中，关键中间体是。双环氧鎓叶立德，其反应性由电荷和环应变的稳定性控制。带有重氮羰基的双环原酸酯的反应由一个亚甲基单元束缚的官能团定量地产生九元多氧环醚，当束缚亚甲基链从1延长至4时，放大效率没有减弱，这表明三环氧叶立德的形成及其环扩张是非常有利的。不仅通过烯醇化物的稳定作用，而且还通过原酸酯中三个醚氧原子的存在，使原酸酯的正电荷离域除了扩环反应外，环醚的氧鎓叶立德还表现出一种有效的新型开环重排反应，从而导致形成被称为高反应性瞬态物质的烯基氧基乙烯酮较少。