Superelectrophilic Fe(III)–Ion Pairs as Stronger Lewis Acid Catalysts for (<i>E</i>)-Selective Intermolecular Carbonyl–Olefin Metathesis
作者:Haley Albright、Hannah L. Vonesh、Corinna S. Schindler
DOI:10.1021/acs.orglett.0c00917
日期:2020.4.17
intermolecular carbonyl–olefin metathesis reaction is described that relies on superelectrophilic Fe(III)-based ionpairs as stronger Lewis acid catalysts. This new catalytic system enables selective access to (E)-olefins as carbonyl–olefin metathesis products. Mechanistic investigations suggest the regioselective formation and stereospecific fragmentation of intermediate oxetanes to be the origin of this
描述了一种分子间羰基-烯烃复分解反应,该反应依赖于超亲电 Fe(III) 基离子对作为更强的路易斯酸催化剂。这种新的催化系统能够选择性地使用 ( E )-烯烃作为羰基-烯烃复分解产物。机理研究表明,中间体氧杂环丁烷的区域选择性形成和立体特异性断裂是这种选择性的来源。优化的条件适用于各种芳基醛和三取代烯烃,并在 28 个示例中得到证明,总产率高达 64%。
Electrogenerated Sm(II)-Catalyzed Carbon Dioxide Reduction for β-Hydrocarboxylation of Styrenes
RadicalcationDiels–Alderreactions by titanium dioxide (TiO2) photocatalysis in lithium perchlorate/nitromethane solution are described. TiO2 photocatalysis promotes reactions between electron-rich dienes and dienophiles, which would otherwise be difficult to accomplish due to electronic mismatching. The reactions are triggered by hole oxidation of the dienophile and are completed by the excited
Orthogonally Protected 1,2-Diols from Electron-Rich Alkenes Using Metal-Free Olefin <i>syn</i>-Dihydroxylation
作者:Ignacio Colomer、Rosimeire Coura Barcelos、Kirsten E. Christensen、Timothy J. Donohoe
DOI:10.1021/acs.orglett.6b02959
日期:2016.11.18
A new method for the stereoselective metal-free syn-dihydroxylation of electron-richolefins is reported, involving reaction with TEMPO/IBX in trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) and the addition of a suitable nucleophile. Orthogonally protected syn 1,2-diols were obtained with high levels of diastereocontrol, and these products were selectively deprotected and selectively functionalized