Hydrogen abstraction from primary amines. Substituent effects on the carbon–nitrogen bond rotation barriers in aminoalkyl radicals
Hydrogen abstraction from primary amines. Substituent effects on the carbon–nitrogen bond rotation barriers in aminoalkyl radicals
复制标题
从伯胺中夺氢。取代基对氨基烷基自由基中碳-氮键旋转势垒的影响。
DOI：
10.1039/p29870001789
复制
发表时间：
1987
影响因子：
3.6
通讯作者：
D. C. Nonhebel
中科院分区：
文献类型：
--
作者：
I. Macinnes;J. Walton;D. C. Nonhebel
t-丁氧基自由基从伯胺RCH2NH2（R = H, Me, Et, Pri, or But）中抽氢，得到的主要是α-氨基烷基自由基。碳氮键的旋转障碍是由交换展宽决定的。对于2-氟乙胺和2-氯乙胺，初始α-氨基烷基自由基失去了卤化氢，得到了合成和抗1-杂氮烯丙基自由基的混合物。而在相同的实验条件下，1-氨基-2,2,2-三氟乙基自由基是稳定的。还考察了甘氨酸甲基酯、丙氨酸丁酯和丙氨酸丁酯在抽氢过程中形成的α-氨基自由基。通过氨基烷基自由基的C-N键旋转势垒估计α-氨基甲基自由基的稳定能。稳定的模式被发现是一致的额外稳定的自由基与俘获取代。
Hydrogen abstraction by t-butoxyl radicals from primary amines RCH2NH2(R = H, Me, Et, Pri, or But) gave mainly α-aminoalkyl radicals which were observed by e.s.r. spectroscopy. The barriers to rotation about the C–N bonds were determined from exchange broadening. For 2-fluoro- and 2-chloro-ethylamine the initial α-aminoalkyl radical lost hydrogen halide to give a mixture of syn- and anti-1-aza-allyl radicals. In contrast, the 1-amino-2,2,2-trifluoroethyl radical was stable under the same experimental conditions. The α-amino radicals formed on hydrogen abstraction from the methyl and t-butyl esters of glycine and the t-butyl ester of alanine were also examined. The stabilisation energy of the α-aminomethyl radical was estimated from the C–N bond rotation barriers of the aminoalkyl radicals. The pattern of stabilisation was found to be consistent with an extra stabilisation in radicals with captodative substitution.