以β-硝基苯乙烯衍生物为底物,丙烯酰胺和N-溴代丁二酰亚胺(NBS)为氮源和卤素源,建立了碳-碳双键上的选择性氨溴加成反应新体系.以二氯甲烷为溶剂,在没有惰性气体保护及乙醇钠促进下,β-硝基苯乙烯衍生物与丙烯酰胺和NBS于室温反应即可高收率地获得α-氨基-β,β-二溴加成产物,最高收率达83%;以甲醇为溶剂,在无水碳酸钠作用下,β-甲基-β-硝基苯乙烯衍生物也可高收率地获得相应的邻位氨溴加成产物,最高收率达97%.共考察了25种不同结构β-硝基苯乙烯衍生物的氨溴加成反应,结果表明,该反应具有广泛的适应性.采用核磁共振波谱及质谱表征了产物的结构,并提出了可能的反应机理.
A new protocol for the high regioselective aminobromination of β-nitrostyrene derivatives with acrylamide and N-Bromobutanimide( NBS) as nitrogen/bromine sources was developed. β-Nitrostyrene derivatives reacted with acrylamide and NBS promoted by CH_3CH_2 ONa at room temperature( without the protection of an inert gaseous atmosphere) in CH_2Cl_2,offered vicinal haloamine products in good yields( up to 83%). For the β-methyl-β-nitrostyrene,the good yields( up to 98%) were also achieved in CH_3 OH promoted by Na_2CO_3.Although the strong electron-donating substituents( e.g.,OCH_3) on the 4-position of benzene ring could deactivated the reaction activity of β-nitrostyrenederi-vetives,the vicinal haloamines were also afforded as the sole addition product. Whereas strong electron-withdrawing substituents( e.g.,NO_2) could activated reaction activity remarkably and the vicinal haloamines were afforded as the sole addition product,too. The result revealed that the addition reaction has a nucleophilic addition feature. The aminobromination of 25 examples of β-nitrostyrenes were investigated and the structure of all products were confirmed by the corresponding nuclear magnetic resonance( NMR) spectra and high resolution mass spectrometer( HRMS). A possible mechanism involving a nucleophilic conjugate addition was proposed.