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

二苯乙炔型分子的两亲性可以以鎓叶立德的形式遗传。虽然醚氧鎓叶立德仍然继续逃避光谱鉴定，但它们的形成已通过动力学测量间接证明，例如，的反应中在此基础上，我们设计了双环和三环氧鎓叶立德的扩环反应，在铑催化下，重氮酮与五至八元环醚反应生成双环氧鎓叶立德，其中连接链是一个亚甲基单元，进行了一种新的三碳扩环反应，有效地形成相应的八至十一元环酮醚。五元至八元环缩醛系链的重氮酮，其中系链是一个或两个亚甲基单元，也经历了类似的放大反应。不仅有铑酮卡宾，而且还有游离卡宾，如亚烷基卡宾 ...更多信息 带有环醚或缩醛的烯表现类似，得到环状二烯醇醚。在所有反应中，关键中间体是双环氧鎓叶立德，其反应活性受电荷稳定性和环张力的控制，双环原酸酯与重氮羰基的反应定量地生成了9元多氧环醚。当束缚亚甲基链从1延长到4时，放大效率不减弱。这表明三环氧鎓叶立德的形成和扩环不仅受到烯醇化物稳定作用的影响，而且还受到原酸酯中存在的三个醚氧原子的影响，醚氧原子使叶立德的正电荷离域，从而促进扩环两性环的形成（1，n-亲两体）结构。除了扩环反应之外，揭示了环醚的氧叶立德显示出有效的新的开环重排反应，导致形成被称为高反应性瞬时物质的烯氧基烯酮。少

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