15N nuclear magnetic resonance studies of azabicycles; unusual deshielding of nitrogen in the 7-azabicyclo[2.2.1]heptyl ring system
作者:Djballah Belkacemi、John W Davies、John R Malpass、Antoinette Naylor (née Bathgate)、Craig R Smith
DOI:10.1016/s0040-4020(01)89045-1
日期:——
samples of derivatives of the 7-azabicyclo[2.2.1]heptyl system were synthesised and 15N NMR spectra were recorded using 15N-enriched and natural abundance samples; separate signals were observed for the two invertomers in N-methyl and N-chloro derivatives. Considerable deshielding was observed in comparison with simple amines and with 8-azabicyclo[3.2.1]octyl and 9-azabicyclo[4.2.1]nonyl analogues.
15的N-富集的7-氮杂双环[2.2.1]庚基系统的衍生物的样品的合成和15使用N个记录NMR谱15的N-富集的和天然丰度的样品; 在N-甲基和N-氯代衍生物中观察到两个反相子的单独信号。与简单的胺以及8-氮杂双环[3.2.1]辛基和9-氮杂双环[4.2.1]壬基类似物相比,观察到相当大的脱屏蔽。化学位移的可预测变化是由于在氮和α-碳处的取代引起的;还研究了在氮原子上的构型,不饱和度以及进一步取代氮原子的影响。