Kinetics, mechanisms, and catalysis of oxygen atom transfer reactions of S-oxide and pyridine N-oxide substrates with molybdenum(IV,VI) complexes: relevance to molybdoenzymes
对(氧化)金催化的选定关键反应的广泛动力学研究集中在催化活性的降低,这是由于吡啶衍生物引起的金(I)催化剂的抑制,如果使用N氧化物作为副产物获得的吡啶衍生物氧气供体。不管它们的市售性如何,都已对受检吡啶衍生物及其相应的N-氧化物进行了选择。特别注意的是迄今为止在大多数反应筛选中都被忽略的实际益处。用GC和1监测测试反应1 H NMR光谱。所接收的反应常数提供了关于杂环的电子结构与催化活性之间的相关性的信息。根据收集的动力学数据,有可能开发出一套基本的三种N氧化物,这些氧化物必须在进一步的氧化金(I)催化反应中加以考虑。
Hydroheteroarylation of Unactivated Alkenes Using <i>N</i>-Methoxyheteroarenium Salts
作者:Xiaoshen Ma、Hester Dang、John A. Rose、Paul Rablen、Seth B. Herzon
DOI:10.1021/jacs.7b02388
日期:2017.4.26
reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%)
Synthesis of Unsymmetrically Substituted Bipyridines by Palladium-Catalyzed Direct C−H Arylation of Pyridine <i>N</i>-Oxides
作者:Sasa Duric、C. Christoph Tzschucke
DOI:10.1021/ol200565u
日期:2011.5.6
Substituted bipyridines were efficiently prepared by direct coupling between pyridine N-oxides and halopyridines using a palladium catalyst. Pyridine N-oxides with electron-withdrawing substitutents gave the best yields. This method allows the convenient preparation of 2,2′-, 2,3′-, and 2,4′-bipyridines which are useful as functionalized ligands for metal complexes or as building blocks for supramolecular
Visible-Light-Induced C2 Alkylation of Pyridine <i>N</i>-Oxides
作者:Wen-Man Zhang、Jian-Jun Dai、Jun Xu、Hua-Jian Xu
DOI:10.1021/acs.joc.6b02891
日期:2017.2.17
A photoredox catalytic method has been developed for the direct C2 alkylation of pyridineN-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridineN-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
Visible‐Light‐Induced
<i>ortho</i>
‐Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
作者:Jinwon Jeon、Yu‐Tao He、Sanghoon Shin、Sungwoo Hong
DOI:10.1002/anie.201912746
日期:2020.1.2
alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilicalkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically
α-Heteroarylation of Thioethers via Photoredox and Weak Brønsted Base Catalysis
作者:Edwin Alfonzo、Sudhir M. Hande
DOI:10.1021/acs.orglett.1c02151
日期:2021.8.6
thioethers to α-thio alkyl radicals and their addition to N-methoxyheteroarenium salts for the redox-neutral synthesis of α-heteroaromatic thioethers. Studies are consistent with a two-step activation mechanism, where oxidation of thioethers to sulfide radical cations by a photoredox catalyst is followed by α-C–H deprotonation by a weak Brønsted base catalyst to afford α-thio alkyl radicals. Further,