The first total synthesis of halistatins 1 and 2 has been completed using Cr-mediated coupling reactions for the C11/C12, C17/C18, and C19/C20 bond formation. For the C11/C12 bond formation, a stoichiometric Ni/Cr-mediated reaction is used to couple an α-quaternary aldehyde with a vinyl iodide. The solubilized Cr-reagent, prepared from CrCl2 and a sulfonamide ligand, allows one to perform the coupling
Cyclopentenones are synthetically versatile structures, and their straightforward construction from alkynone substrates by employing synthetically streamlining C-H insertion is conceptually appealing and of high synthetic potential. But, its implementation is very limited. Herein we report a Au-catalyzed version, which affords 2-bromocyclopent-2-en-1-ones with a broad scope and synthetically desirable
环戊烯酮是合成通用的结构,它们通过合成流线型 CH 插入从炔酮底物直接构建在概念上具有吸引力且具有高合成潜力。但是,它的实施非常有限。在此我们报告了一种 Au 催化的版本,它提供了具有广泛范围和合成所需的非对映选择性的 2-bromocyclopent-2-en-1-ones。所提出的能够插入未活化 CH 键的关键中间体是一种完全功能化的金亚乙烯基,它是通过一种新的分子间策略产生的。这种可能的金亚乙烯基的灵活获取为探索其多功能反应性提供了各种机会。
Propargylic Oxidations Catalyzed by Dirhodium Caprolactamate in Water: Efficient Access to α,β-Acetylenic Ketones
作者:Emily C. McLaughlin、Michael P. Doyle
DOI:10.1021/jo800382p
日期:2008.6.1
hydroperoxide (T-HYDRO) is a highly effective catalytic oxidation protocol for the selective C−H oxidation of alkynes to propargylic ketones. The oxidation occurs readily in aqueous solvent under mild conditions with an inexpensive and easily handled oxidant. α,β-Acetylenic carbonyl compounds are formed in up to 80% isolated yield.