[2+2+2] Annulation of N-(1-Naphthyl)acetamide with Two Alkynoates via Cleavage of Adjacent C–H and C–N Bonds Catalyzed by an Electron-Deficient Rhodium(III) Complex
non-oxidative [2+2+2] annulation of N-(1-naphthyl)acetamide with two alkynoates via cleavage of the adjacent C–H and C–N bonds to give densely substituted phenanthrenes undermildconditions (at 40 °C under air). In this reaction, a dearomatized spiro compound was isolated, which may support the formation of a cationic spiro rhodacycle intermediate in the catalytic cycle. The use of N-(1-naphthyl)acetamide in
Reverse Regioselectivity in the Palladium(II) Thiourea Catalyzed Intermolecular Pauson-Khand Reaction
作者:Na Wu、Lujiang Deng、Lianzhu Liu、Qi Liu、Chuangchuang Li、Zhen Yang
DOI:10.1002/asia.201200783
日期:2013.1
Which way? Palladium thiourea catalyzed Pauson–Khand reaction of norbornene with substituted alkynoates to afford selectively either α‐carboxylated adducts or β‐carboxylated adducts with the reverse regioselectivity has been demonstrated for the first time. Control of the regioselectivity in this transformation is governed by the addition of LiCl. A mechanistic interpretation to account for this observed
of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted
描述了使用乙醇作为氢源实现未活化烯烃的转移氢化 (TH) 的第一种通用催化方法。已经开发出一种新的 NCP 型钳形铱络合物 (BQ-NCOP)IrHCl,其含有刚性苯并喹啉主链,可有效、温和地将未活化的 CC 多键与乙醇进行 TH,形成乙酸乙酯作为唯一的副产品。各种烯烃,包括多取代的烷基烯烃、芳基烯烃和杂原子取代的烯烃,以及含 O 或 N 的杂芳烃和内部炔烃,都是合适的底物。重要的是,(BQ-NCOP)Ir/EtOH 系统在反应性官能团(如酮和羧酸)存在下对烯烃氢化表现出高化学选择性。此外,与 C2D5OD 的反应为氘标记化合物提供了一条便捷的途径。详细的动力学和机理研究表明,单取代烯烃(如 1-辛烯、苯乙烯)和多取代烯烃(如环辛烯 (COE))表现出基本的机理差异。乙醇的 OH 基团在苯乙烯反应中显示出正常的动力学同位素效应 (KIE),但在 COE 的情况下显示出显着的反向 KIE。对
Development of Gold-catalyzed [4+1] and [2+2+1]/[4+2] Annulations between Propiolate Derivatives and Isoxazoles
作者:Rajkumar Lalji Sahani、Rai-Shung Liu
DOI:10.1002/anie.201610665
日期:2017.1.19
new gold‐catalyzed annulations of isoxazoles with propiolates have been developed. Most isoxazoles follow an initial O attack on the alkyne to afford a [4+1] annulation product. This process results in a remarkable alkyne cleavage of initial propiolates. Unsubstituted isoxazoles proceed through an N attack step to yield formal [2+2+1]/[4+2] annulation products. These two annulation products arise initially
Platinum-Catalyzed Hydrosilylations of Internal Alkynes: Harnessing Substituent Effects to Achieve High Regioselectivity
作者:Douglas A. Rooke、Eric M. Ferreira
DOI:10.1002/anie.201108714
日期:2012.3.26
Rule of thumb: The high yielding title reaction is described with a focus on understanding the factors that govern the regioselectivity of the process (see scheme). Electronic, steric, and functional group properties all influence the selectivity, an understanding of which allows the selective formation of trisubstituted vinylsilanes, which are synthetically useful compounds for accessing stereodefined