Nitroxides (aminyl oxydes) - XL. ESR spectroscopic studies of β-sulfonyl substituted vinyl nitroxides and of a vinylogous nitronyl nitroxide
作者:Hans Günter Aurich、Klaus-Dieter Möbus
DOI:10.1016/s0040-4020(01)89107-9
日期:1989.1
Oxidation of hydroxylamines 1 affords the vinyl nitroxides 4 via 2 and 3. The vinylogous nitronyl nitroxide 5 is formed upon oxidation of 1h. Whereas the methyl group X in 4a is freely rotating, rotation of substituents X in 4b–d is restricted as is indicated by their ESR spectra. Particularly, the less hindered vinyl nitroxides 4e–g form spin adducts 6 or 7 with their precursor nitrones 3. 4b coexists
羟胺1的氧化通过2和3得到乙烯基氮氧化物4。氧化1h会形成乙烯基亚硝酰氮氧化物5。尽管4a中的甲基X是自由旋转的,但4b-d中的取代基X的旋转却受到其ESR光谱的限制。特别是,受阻较少的乙烯基氮氧化物4e-g与前体硝酮3形成自旋加合物6或7。4b与6b或7b共存在−30°至+ 15°C之间,低于−30°C只能检测到6b / 7b,高于+ 15°C只能检测到4b。由于π系统的扭曲,在室温及以下,两个5个NO基团不相等。但是,动态过程使它们在+ 65°C时等效。