A Catalytic Borylation/Dehalogenation Route to o-Fluoro Arylboronates
摘要:
A two-step Ir-catalyzed borylation/Pd-catalyzed dehalogenation sequence allows for the net synthesis of fluoroarenes where the boronic ester is ortho to fluorine. Key elements of this approach include the use of a halogen para to the fluorine to block meta Ir-catalyzed borylation and the chemoselective Pd-catalyzed dehalogenation by KF activated polymethylhydrosiloxane (PMHS).
Visible Light-Induced Borylation of C–O, C–N, and C–X Bonds
作者:Shengfei Jin、Hang. T. Dang、Graham C. Haug、Ru He、Viet D. Nguyen、Vu T. Nguyen、Hadi D. Arman、Kirk S. Schanze、Oleg V. Larionov
DOI:10.1021/jacs.9b12519
日期:2020.1.22
photocatalytic borylation method that can effect borylation of a wide range of substrates, including strong C‒O bonds, remains elusive. Herein, we report a general, metal-free visible light-induced photocatalytic borylation platform that enables borylation of electron rich derivatives of phenols and anilines, chloroarenes, as well as other haloarenes. The reac-tion exhibits excellent functional group
硼酸是中心重要的功能基序和合成前体。可见光诱导的硼酸化可以提供结构多样化的硼酸盐,但一种广泛有效的光催化硼酸化方法可以影响包括强 C-O 键在内的多种底物的硼化,仍然难以实现。在此,我们报告了一种通用的、无金属的可见光诱导光催化硼化平台,该平台能够对苯酚和苯胺、氯芳烃以及其他卤代芳烃的富电子衍生物进行硼化。该反应表现出优异的官能团耐受性,正如一系列结构复杂底物的硼化反应所证明的那样。值得注意的是,该反应是由吩噻嗪催化的,这是一种简单的有机光催化剂,MW< 200通过质子耦合电子转移机制介导了以前无法实现的可见光诱导的苯酚衍生物单电子还原,还原电位为~-3 V vs SCE。机理研究指出了光催化剂-碱相互作用的关键作用。
Cobalt-Catalyzed Regioselective Borylation of Arenes: N-Heterocyclic Silylene as an Electron Donor in the Metal-Mediated Activation of C−H Bonds
C−H Borylation of arenes has been a subject of great interest recently because of its atom‐economy and the wide applicability of borylated products in value‐added synthesis. A new bis(silylene)cobalt(II) complex bearing a bis(N‐heterocyclic silylene)‐pyridine pincer ligand (SiNSi) has been synthesized and structurally characterized. It enabled the regioselective catalytic C−H borylation of pyridines
Compounds disclosed herein are bradykinin B1 antagonist compounds useful in the treatment or prevention of symptoms such as pain and inflammation associated with the bradykinin B1 pathway.
Rhodium-Catalyzed Intermolecular C–H Silylation of Arenes with High Steric Regiocontrol
作者:Chen Cheng、John F. Hartwig
DOI:10.1126/science.1248042
日期:2014.2.21
has widespread applications in synthetic chemistry. The regioselectivity of these reactions is often controlled by directing groups or steric hindrance ortho to a potential reaction site. Here, we report a catalytic intermolecular C–H silylation of unactivated arenes that manifests very high regioselectivity through steric effects of substituents meta to a potential site of reactivity. The silyl moiety
C(sp<sup>2</sup>)–H Borylation of Fluorinated Arenes Using an Air-Stable Cobalt Precatalyst: Electronically Enhanced Site Selectivity Enables Synthetic Opportunities
作者:Jennifer V. Obligacion、Máté J. Bezdek、Paul J. Chirik
DOI:10.1021/jacs.6b13346
日期:2017.2.22
Cobalt catalysts with electronically enhanced site selectivity have been developed, as evidenced by the high ortho-to-fluorine selectivity observed in the C(sp2)-H borylation of fluorinated arenes. Both the air-sensitive cobalt(III) dihydride boryl 4-Me-(iPrPNP)Co(H)2BPin (1) and the air-stable cobalt(II) bis(pivalate) 4-Me-(iPrPNP)Co(O2CtBu)2 (2) compounds were effective and exhibited broad functional