Pyriporphyrins with three different orientations for the pyridine moiety have been prepared using a '3 + 1' strategy. The nonaromatic pyriporphyrins are stable so long as phenyl substituents are present at the meso-positions adjacent to the pyridine ring. An aromatic dihydropyriporphyrin with an external CO2Ph protective group has also been prepared from 2,4-pyridinedicarbaldehyde.
Pyriporphyrins with three different orientations for the pyridine moiety have been prepared using a '3 + 1' strategy. The nonaromatic pyriporphyrins are stable so long as phenyl substituents are present at the meso-positions adjacent to the pyridine ring. An aromatic dihydropyriporphyrin with an external CO2Ph protective group has also been prepared from 2,4-pyridinedicarbaldehyde.
The main side-products arise from direct, non-carbonylative cross-coupling. Under optimized conditions, benzoylpyridines are recovered in high yields (80–95%). The order of reactivity decreases from iodo- to bromopyridines and from 2-, 4- to 3-substituted halopyridines. The reactivity of dihalopyridines has been investigated; 2,6-dibromopyridine (7) and 3,5-dibromopyridine (11) are selectively transformed
Domino Reactions Involving the Branched C–N and C═C Cleavage of Enaminones Toward Pyridines Synthesis
作者:Jie-Ping Wan、Youyi Zhou、Shuo Cao
DOI:10.1021/jo5018266
日期:2014.10.17
cascade reactions of enaminones and ammonium chloride have led to the unprecedented synthesis of 4-unsubstituted pyridines of both symmetrical and unsymmetrical structures. Under the aerobic copper-catalyzed conditions, the branched transformations of enaminones with C–N and C═C bond cleavage provide the C2-C3/C5-C6 and C4 building blocks to construct the pyridine ring, respectively. The C═C cleavage
Metal-free oxidative activation of enaminone C C bond by ammonium halide and DMSO: An access to synthetic pyridines
作者:Qianqian Gu、Kun He、Weikun Zeng、Ling Jiang、Zhi Qiao、Jun Lin、Yi Jin
DOI:10.1016/j.tetlet.2022.153993
日期:2022.8
Herein, we reported a metal-free oxidative activation of enaminone CC double bond by ammoniumhalide and DMSO to synthetic pyridines. This reaction proceeded smoothly without metal catalysts, strong oxidants, or free radical initiators. In addition, no direct addition of halogen or hydrogen halide is required, providing rapid access to a variety of 3,5-disubstituted-pyridines in moderate to excellent
在此,我们报道了卤化铵和 DMSO 对烯胺酮 C C 双键的无金属氧化活化合成吡啶。该反应在没有金属催化剂、强氧化剂或自由基引发剂的情况下顺利进行。此外,无需直接添加卤素或卤化氢,以中等至优异的产率快速获得各种 3,5-二取代吡啶。
Ruegheimer; Kronthal, Justus Liebigs Annalen der Chemie, 1894, vol. 280, p. 52
作者:Ruegheimer、Kronthal
DOI:——
日期:——
Ruegheimer; Herzfeld, Justus Liebigs Annalen der Chemie, 1894, vol. 280, p. 70