A highly efficient and regioselectivedirectC–H trifluoromethylation of pyridine based on an N-methylpyridine quaternary ammonium activation strategy has been developed. A variety of trifluoromethylpyridines can be obtained in good yield and excellent regioselectivity by treating the pyridinium iodide salts with trifluoroacetic acid in the presence of silver carbonate in N,N-dimethylformamide. The
The first Pd/Cu catalyzed selective C2-alkenylation of pyridines with internal alkynes has been developed via the pyridinium salt activation strategy. Importantly, the configuration of the product alkenylpyridines could be tuned by the choice of the proper N-alkyl group of the pyridinium salts, thus allowing for both the Z- and E-alkenylpyridines synthesized with good regio- and stereoselectivity.
Aerobic Oxidation of Pd<sup>II</sup> to Pd<sup>IV</sup> by Active Radical Reactants: Direct C–H Nitration and Acylation of Arenes via Oxygenation Process with Molecular Oxygen
oxidative C–H nitration and acylation of arenes with simple and readily available tert-butyl nitrite (TBN) and toluene as the radical precursors has been developed. Molecular oxygen is employed as the terminal oxidant and oxygen source to initiate the active radical reactants. Many different directing groups such as pyridine, pyrimidine, pyrazole, pyridol, pyridylketone, oxime, and azo groups can be employed
已经开发了钯催化的好氧氧化C–H硝化和芳烃与简单易用的亚硝酸叔丁酯(TBN)和甲苯作为自由基前体的酰化反应。分子氧被用作末端氧化剂和氧源以引发活性自由基反应物。在这些新颖的转化中可以使用许多不同的导向基团,例如吡啶,嘧啶,吡唑,吡啶醇,吡啶基酮,肟和偶氮基团。通过自由基过程的Pd II / Pd IV催化循环是这些氧化的CH–H硝化和酰化反应的最可能途径。
Synthesis of 2-Formylpyrroles from Pyridinium Iodide Salts
synthesis of 2-formylpyrroles from pyridinium salts is reported. This protocol enables the synthesis of diversely substituted 2-formylpyrroles in good yields under operationally simple conditions. The detailed mechanistic studies reveal that the reaction proceeds via a novel H2O-triggered ring opening of the pyridinium salt and a subsequent intramolecularly nucleophilic addition sequence.
A cationic cobalt(III)‐catalyzeddirectCH amidation of unactivated (hetero)arenes and alkenes by using 1,4,2‐dioxazol‐5‐ones as the amidating reagent has been developed. This transformation proceeds efficiently under external oxidant‐free conditions with a broad substrate scope. Moreover, 6‐arylpurine compounds, which often exhibit high potency in antimycobacterial, cytostatic, and anti‐HCV activities