Reactivity of Thioaldehyde: Cyclization Reaction of 6-Amino-1,3-dimethyl-5- thioformyluracil with Enamines into Pyrido[2,3-d]pyrimidine-2,4-(1H,3H)-diones
Nucleophilic Reaction upon Electron-Deficient Pyridone Derivatives. X.One-Pot Synthesis of 3-Nitropyridines by Ring Transformation of 1-Methyl-3,5-dinitro-2-pyridone with Ketones or Aldehydes in the Presence of Ammonia
作者:Yasuo Tohda、Miyuki Eiraku、Takao Nakagawa、Yumi Usami、Masahiro Ariga、Toshihide Kawashima、Keita Tani、Hiroko Watanabe、Yutaka Mori
DOI:10.1246/bcsj.63.2820
日期:1990.10
The reaction of 1-methyl-3,5-dinitro-2-pyridone (1a) with ketones or aldehydes in the presence of ammonia gave alkyl- and/or aryl-substituted 3-nitropyridines (6) in moderate to high yields. Enamines derived from the ketones gave better results than did the ketones themselves; on the other hand, those derived from the aldehydes gave no 6 at all. On the basis of deuterium-labeled experiments, a mechanism comprising competitive ring transformations of 1a is proposed.
Kinetics of Electrophilic Fluorinations of Enamines and Carbanions: Comparison of the Fluorinating Power of N–F Reagents
作者:Daria S. Timofeeva、Armin R. Ofial、Herbert Mayr
DOI:10.1021/jacs.8b07147
日期:2018.9.12
leaving groups and the calculated fluorine plus detachment energies are discussed. The rate constants for the reactions with deoxybenzoin-derived enamines follow the linear free energy relationship log k2(20 °C) = sN( N + E) which allows the empirical electrophilicity parameters E for these fluorinating agents to be derived from the measured rate constants and the tabulated N and sN parameters for the nucleophiles
在乙腈中研究了烯胺和碳负离子与常用氟化试剂、N-氟苯磺酰亚胺 (NFSI)、N-氟吡啶盐、Selectfluor 和 N-氟化金鸡纳生物碱的反应动力学。反应遵循二级动力学,从测得的速率常数可以推导出氟化是通过亲核试剂在氟处的直接攻击进行的,而不是通过 SET 过程进行的。讨论了氟化速率与离核离去基团的 p KaH 值和计算的氟加脱离能的相关性。与脱氧安息香衍生的烯胺反应的速率常数遵循线性自由能关系 log k2(20 °C) = sN( N + E),这使得这些氟化剂的经验亲电性参数 E 可以从测量的速率常数中得出以及亲核试剂的列表 N 和 sN 参数。尽管测得的速率常数与通过这种关系计算的速率常数的偏差大于以 Csp2 为中心的亲电试剂与亲核试剂的反应,但表明这项工作中报道的亲电参数 E 能够合理化已知的氟化反应,因此,推荐作为设计新的亲电子氟化的指南。