Aryl Imidazylates and Aryl Sulfates As Electrophiles in Metal-Free ArSN1 Reactions
摘要:
Some oxygen-bonded substituents were investigated as leaving groups in photoinduced ArSN1 reactions. Irradiation of aryl imidazylates and of the corresponding imidazolium salts mainly caused homolysis of the ArO-S bond. However, previously unexplored trifluoroethoxy aryl sulfates were found to undergo efficient metal-free arylation. The sulfates were conveniently generated in situ by dissolving the corresponding imidazolium salts in basic 2,2,2-trifluoroethanol.
Dynamic multiligand catalysis: A polar to radical crossover strategy expands alkyne carboboration to unactivated secondary alkyl halides
作者:Shin-Ho Kim-Lee、Pablo Mauleón、Ramón Gómez Arrayás、Juan C. Carretero
DOI:10.1016/j.chempr.2021.06.002
日期:2021.8
triggers cooperative polar/radical pathways in a single catalytic cycle. This strategy has been applied to address a restricting limitation inherent to Cu-catalyzed B2pin2-carboboration of alkynes—the very low reactivity of the intermediate vinyl-Cu(I) species, which renders conventional methods ineffective with alkyl electrophiles other than simple primary halides. The crossover strategy enabled by
我们描述了基于前所未有的动态多配体配位池的 Cu 催化的双重策略,该池在单个催化循环中触发合作的极性/自由基途径。该策略已被应用于解决 Cu 催化的 B 2 pin 2固有的限制性限制-炔烃的碳硼化——中间体乙烯基-Cu(I) 物质的反应性非常低,这使得传统方法对烷基亲电试剂无效,而不是简单的伯卤化物。通过有机金属中间体中的配体交换实现的交叉策略克服了这一反应性问题,将碳硼化的范围扩大到未活化的仲烷基卤化物,并开辟了获得立体定义的四取代乙烯基硼酸酯的新途径。该方法具有区域选择性和立体选择性,显示出优异的官能团耐受性,并允许在任一反应伙伴处掺入复杂的碳环和杂环片段。
作者:Qi-Liang Yang、Yi-Kang Xing、Xiang-Yang Wang、Hong-Xing Ma、Xin-Jun Weng、Xiang Yang、Hai-Ming Guo、Tian-Sheng Mei
DOI:10.1021/jacs.9b11915
日期:2019.12.4
Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C-H functionalization, yet this type of transformation has thus far mainly been limited to arene C-H functionaliza-tion. Herein, we report the development of electrochemi-cal vinylic C-H functionalization of acrylic acids with al-kynes. In this reaction an iridium catalyst enables C-H/O-H
Recyclable heterogeneous metal foil-catalyzed cyclopropenation of alkynes and diazoacetates under solvent-free mechanochemical reaction conditions
作者:Longrui Chen、Devonna Leslie、Michael G. Coleman、James Mack
DOI:10.1039/c8sc00443a
日期:——
cyclopropenation of terminal and internal alkynes under mechanochemical reactionconditions. This methodology enables the functionalization of a wide range of terminal or internal alkynes under ambient, aerobic, and solvent-freeconditions. Finally, we have demonstrated a unique and versatile one-pot domino Sonogashira-cyclopropenation mechanochemical reaction for the formation of complex cyclopropenes.
Palladium-Catalyzed Sonogashira Coupling of Aryl Mesylates and Tosylates
作者:Pui Ying Choy、Wing Kin Chow、Chau Ming So、Chak Po Lau、Fuk Yee Kwong
DOI:10.1002/chem.201001269
日期:2010.9.3
Up to speed: The first general and mild protocol for the Sonogashiracoupling of aryl mesylates is presented (see scheme). The coupling intermediate also provides facile access to 2‐substituted isoquinolines.
Chalcones can unusually serve as the precursors of acetophenones which then undergo formal (4+1) cyclization with internal alkynes via rhodium(III) catalysis in a regio- and chemoselective manner. 1-Indanones containing quaternary carbon centers along with reusable aryl aldehydes were formed by this annulation. This discovery enables a practical two-step protocol to indanones from the reaction of acetophenones