Domino Electrocyclization/Azide-Capture/Schmidt Rearrangement of Dienones: One-Step Synthesis of Dihydropyridones from Simple Building Blocks
作者:Dong Song、Ali Rostami、F. G. West
DOI:10.1021/ja071041z
日期:2007.10.1
proceed via nucleophilic trapping of the 2-oxidocyclopentenyl intermediate, followed by Schmidt-type rearrangement to give a transient 1,4-dipole. In unsymmetrical examples, complete regioselectivity in favor of attack on the less substituted side was observed. The 1,4-dipole intermediate then rearranges to the observed dihydropyridone, via either proton transfer or 1,5-hydride shift.
Olefination of α,α′-Divinyl Ketones through Catalytic Meyer−Schuster Rearrangement
作者:Curtis J. Rieder、Karl J. Winberg、F. G. West
DOI:10.1021/jo101497f
日期:2011.1.7
followed by catalytic Meyer−Schuster rearrangement has been developed for the olefination of 1,4-pentadien-3-ones to afford [3]dendralenes. Many of the traditional methods for the Meyer−Schuster rearrangement of alkynyl carbinols are not suitable with these highly unsaturated substrates because of their acid sensitivity. Unexpected reactivity during attempted rearrangement, including Nazarov-type electrocyclizations
Zeolites are the most used catalysts worldwide in petrochemistry processes, with particular ability to stabilizecarbocations. However, the use of zeolites in organicsynthesis is still scarce. We show here that representative carboxonium-mediated organic reactions, such as the Nazarov cyclization and the tert-butylation of alcohols with tert-butyl acetate, typically performed with very strong acid
Site‐ and Enantioselective Iridium‐Catalyzed Desymmetric Mono‐Hydrogenation of 1,4‐Dienes
作者:Haibo Wu、Hao Su、Erik J. Schulze、Bram B. C. Peters、Mark D. Nolan、Jianping Yang、Thishana Singh、Mårten S. G. Ahlquist、Pher G. Andersson
DOI:10.1002/anie.202107267
日期:2021.8.23
The control of site selectivity in asymmetric mono-hydrogenation of dienes or polyenes remains largely underdeveloped. Herein, we present a highly efficient desymmetrization of 1,4-dienes via iridium-catalyzed site- and enantioselective hydrogenation. This methodology demonstrates the first iridium-catalyzed hydrogenative desymmetriation of meso dienes and provides a concise approach to the installation
二烯或多烯不对称单氢化中位点选择性的控制在很大程度上仍然不发达。在此,我们提出了一种通过铱催化的位点和对映选择性氢化对 1,4-二烯进行高效去对称化的方法。该方法展示了第一个铱催化的内消旋二烯的氢化去对称作用,并提供了一种在烯烃附近安装两个邻位立构中心的简明方法。一系列二乙烯基甲醇和二乙烯基碳酰胺底物获得了高分离产率(高达 96%)和优异的非对映选择性和对映选择性(高达 99:1 dr 和 99% ee)。DFT 计算表明,羟基氧和反应氢化物之间的相互作用是二乙烯基甲醇去对称化的立体选择性的原因。根据计算的能量分布,应用模拟产品随时间分布的模型来显示该过程的直观动力学。通过天然产物萨拉戈酸A和(+)-invictolide的关键中间体的合成证明了该方法的有效性。
Cellulose sulfonic acid as a green, efficient, and reusable catalyst for Nazarov cyclization of unactivated dienones and pyrazoline synthesis
作者:Zahra Daneshfar、Ali Rostami
DOI:10.1039/c5ra19773b
日期:——
has been developed. Cellulose sulfonic acid (CSA) not only was able to induce the cyclization of “unactivated” dienones generating cyclopentenoids; it was also able to trigger the cyclization of α,β-unsaturated hydrazones giving rise to pyrazolines in excellent yields under green reaction conditions. The ease of catalyst recovery and reusability, short reaction time, simple experimental and work-up procedure;