动力学数据报道了1-甲基-3-硝基吡啶鎓阳离子与其假碱(氢氧化物加合物)的平衡,以及该阳离子被1-苄基-1,4-二氢烟碱酰胺还原的动力学数据。当该吡啶鎓阳离子与碱水溶液混合时,C-2氢氧化物加合物是动力学控制的产物(pK R + = 11.6),但是,这种物质重新排列成C-4加合物,成为热力学上更稳定的产物(pK R + = 9.42)。 。可以分析此平衡的pH依赖性,得出k OH = 1600 M -1 s -1氢氧根离子攻击该阳离子的C-4。用1-苄基-1,4-二氢烟碱酰胺还原吡啶鎓阳离子似乎仅在C-4处发生,二级速率常数k 2 = 0.72 M -1 s -1和k 2 H / k 2 D = 2.0 in 20%CH 3 CN-80%H 2 O,离子强度1.0,25°C。
We report herein a visible light-mediated C-H hydroxyalkylation of quinolines and isoquinolines that proceeds via a radical path. The process exploits the excited-state reactivity of 4-acyl-1,4-dihydropyridines, which can readily generate acyl radicals upon blue light absorption. By avoiding the need for external oxidants, this radical-generating strategy enables a departure from the classical, oxidative
← S0 transitions exhibit clear 0–0 bands at hν0–0 = 27868 and 42230 cm–1, for protonated quinoline, and at hν0–0 = 28043 and 41988 cm–1, for protonated isoquinoline. Active vibrations in the spectra were assigned with the help of calculated normal modes, looking very similar to those of the structurally related protonated naphthalene. Finally, we have observed that the bandwidths associated with the
Relative reactivities of heteroaromatic cations towards reduction by 1,4-dihydronicotinamides
作者:John W. Bunting、Judy L. Bolton
DOI:10.1016/s0040-4020(01)87506-2
日期:1986.1
reported for the equilibration of the 1-methyl-3-nitropyridinium cation with its pseudobase (hydroxide adduct) and for the reduction of this cation by 1-benzyl-1, 4-dihydronicotinamide. The C-2 hydroxide adduct is the kinetically controlled product (pKR+ = 11.6) when this pyridiniumcation is mixed with aqueous base, however, this species rearranges to the C-4 adduct as the themodynamically more stable product
动力学数据报道了1-甲基-3-硝基吡啶鎓阳离子与其假碱(氢氧化物加合物)的平衡,以及该阳离子被1-苄基-1,4-二氢烟碱酰胺还原的动力学数据。当该吡啶鎓阳离子与碱水溶液混合时,C-2氢氧化物加合物是动力学控制的产物(pK R + = 11.6),但是,这种物质重新排列成C-4加合物,成为热力学上更稳定的产物(pK R + = 9.42)。 。可以分析此平衡的pH依赖性,得出k OH = 1600 M -1 s -1氢氧根离子攻击该阳离子的C-4。用1-苄基-1,4-二氢烟碱酰胺还原吡啶鎓阳离子似乎仅在C-4处发生,二级速率常数k 2 = 0.72 M -1 s -1和k 2 H / k 2 D = 2.0 in 20%CH 3 CN-80%H 2 O,离子强度1.0,25°C。
Reactivity of the 4,5-Didehydroisoquinolinium Cation
作者:Nelson R. Vinueza、Enada F. Archibold、Bartłomiej J. Jankiewicz、Vanessa A. Gallardo、Steven C. Habicht、Mohammad Sabir Aqueel、John J. Nash、Hilkka I. Kenttämaa
DOI:10.1002/chem.201103628
日期:2012.7.9
The chemical properties of a 1,8‐didehydronaphthalene derivative, the 4,5‐didehydroisoquinolinium cation, were examined in the gasphase in a dual‐cell Fourier‐transform ioncyclotronresonance (FT‐ICR) mass spectrometer. This is an interesting biradical because it has two radical sites in close proximity, yet their coupling is very weak. In fact, the biradical is calculated to have approximately degenerate