ylides derived from short-chain trialkylphosphines in the Wittig-type olefinationreactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy
Mizoroki–Heck Reaction of Unstrained Aryl Ketones via Ligand-Promoted C–C Bond Olefination
作者:Mei-Ling Wang、Hui Xu、Han-Yuan Li、Biao Ma、Zhen-Yu Wang、Xing Wang、Hui-Xiong Dai
DOI:10.1021/acs.orglett.1c00296
日期:2021.3.19
Mizoroki–Heck reaction of unstrained arylketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C–C bond cleavage. Various (hetero)arylketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived arylketones demonstrate the synthetic utility
Synthesis of Stilbenes by Rhodium-Catalyzed Aerobic Alkenylation of Arenes via C–H Activation
作者:Xiaofan Jia、Lucas I. Frye、Weihao Zhu、Shunyan Gu、T. Brent Gunnoe
DOI:10.1021/jacs.0c03935
日期:2020.6.10
Arenealkenylation is commonly achieved by late transition metal-mediated C(sp2)-C(sp2) cross-coupling, but this strategy typically requires prefunctionalized substrates (e.g., with halides or pseudohalides) and/or the presence of a directing group on the arene. Transition metal-mediated areneC-Hactivation and alkenylation offers an alternative method to functionalize arene substrates. Herein, we
General Olefin Synthesis by the Palladium‐Catalyzed Heck Reaction of Amides: Sterically Controlled Chemoselective NC Activation
作者:Guangrong Meng、Michal Szostak
DOI:10.1002/anie.201507776
日期:2015.11.23
Metal‐catalyzed reactions of amides proceeding via metal insertion into the NCO bond are severely underdeveloped due to resonance stabilization of the amide bond. Herein we report the first Heck reaction of amides proceeding via highly chemoselective NCO cleavage catalyzed by Pd0 utilizing amide bond ground‐state destabilization. Conceptually, this transformation provides access to a myriad of metal‐catalyzed
Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst
作者:Bernhard J. Gregori、Felix Schwarzhuber、Simon Pöllath、Josef Zweck、Lorena Fritsch、Roland Schoch、Matthias Bauer、Axel Jacobi von Wangelin
DOI:10.1002/cssc.201900926
日期:2019.8.22
stereoselective hydrogenation of alkynes constitutes one of the key approaches for the construction of stereodefined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. This study concerns a simple catalyst comprised of the commercial chemicals iron(II) acetylacetonate and diisobutylaluminum hydride, which enables the Z-selective semihydrogenation of alkynes under near ambient
炔烃的立体选择性加氢构成构造立体烯烃的关键方法之一。大多数常规方法利用贵金属和有毒金属催化剂。这项研究涉及一种由工业化学品乙酰丙酮铁(II)和氢化二异丁基铝组成的简单催化剂,该催化剂能够在接近环境条件(1-3 bar H2、30°C,5 mol%[Fe] )。既不需要复杂的催化剂制备也不需要添加配体。机理研究(动力学中毒,X射线吸收光谱法,TEM)强烈表明了小铁簇和颗粒催化剂的运行。