mixtures of isomers and substantial polymerization. The reaction took place under exceptionally mild reaction conditions and very low catalyst loading (0.5 mol %). DFT calculations disclose the mechanistic features of the isomerization and account for the high selectivity displayed by the B(C6 F5 )3 catalyst. The synthetic applicability of the newreaction is demonstrated by the preparation of γ-chiral
Exploiting the Lithiation-Directing Ability of Oxetane for the Regioselective Preparation of Functionalized 2-Aryloxetane Scaffolds under Mild Conditions
作者:Donato Ivan Coppi、Antonio Salomone、Filippo Maria Perna、Vito Capriati
DOI:10.1002/anie.201109113
日期:2012.7.23
Oxetane nudges in the DoM direction! Regioselective ortho‐lithiation induced by an oxetane ring has been achieved. The reaction provides easy access to ortho‐functionalized 2‐aryloxetanes also through a lithiation/borylation Suzuki–Miyaura cross‐coupling. The lithiation‐directing ability of oxetane and the proton transfer mechanism have been investigated by competitive metalation and kinetic isotope
2-Lithiated-2-phenyloxetane: a new attractive synthon for the preparation of oxetane derivatives
作者:Donato Ivan Coppi、Antonio Salomone、Filippo Maria Perna、Vito Capriati
DOI:10.1039/c1cc13670d
日期:——
A valuable and direct method to access 2-substituted-2-phenyloxetanes by electrophilic quenching of the corresponding 2-lithiated derivative has, for the first time, been described. 2-Lithiated-2-phenyloxetane was found to be configurationally unstable. Evidence is presented to show that electron-transfer processes are also operative in the coupling reactions with electrophiles.
with elements of group 13 (B, Al, Ga, In, Tl) have been used multiple times as canonical LAs.9 One of the most common strategies to fine tune the properties of acids in order to convert them into Lewis superacids is by employing electron-withdrawing substituents (R=EWG). Numerous successful examples can be found in the chemistry of LAs bearing fluorinated aryl substituents, denoted as E(ArF).10, 11 While
介绍 贵金属在均相催化中表现出出色的功效,为众多全合成做出了重大贡献。1, 2然而,对不依赖昂贵过渡金属的催化转化的需求日益增长。3因此,人们对探索源自第一行和主族丰富金属的催化剂的兴趣与日俱增。路易斯酸(LA)催化展示了该领域不断扩展的前景。4 LA 是可以在其空轨道中接受电子对的分子。5 Olah 引入的术语“路易斯超强酸”对强于无水 AlCl 3的酸进行了分类。6 Krossing 和同事后来提出定义那些在气相中比单体 SbF 5更强的 LA。7有多种方法可以衡量 LA 的强度。一般来说,它们涉及吸引力(静电、共价、色散)和排斥相互作用的折衷。Greb 最近报道了一项广泛的研究,对一组强 LA 的路易斯超酸性进行了分类。8在这方面,含有第 13 族元素(B、Al、Ga、In、Tl)的化合物 ER 3已多次用作标准 LA。9 微调酸的性质以将其转化为路易斯超强酸的最常见策略之一是使用吸电子取代基