Ammonia-bromo Addition Of ?-nitrostyrene Derivative/aliphatic Amide/NBS And Its Halogen-hydrogen Exchange Reaction

In this thesis, a new protocol for the high regioselective aminobromination of ?-nitrostyrene derivatives with aliphatic amide and NBS as nitrogen/bromine sources was developed. Based on the analysing structrural characteristic of the products obtained from above aminobromination, a halogen-hydrogen exchange reaction has been established between the halogen of the products and the hydrogen in the active methylene compounds such as malononitrile. Based on the experiments, two kinds of possible reaction mechanism were proporsed. Two main contents are included in this thesis: 1. Aminobromination of ?-nitrostyrene derivatives with aliphatic amide and NBSBecause the combination of amide and NBS could be used as a nitrogen/halogen source, a new protocol for the aminobromination of ?-nitrostyrene derivatives with acrylamide or valeramide and NBS as nitrogen/bromine sources was developed at room temperature without the any of protection of inert gaseous. This method has advantages of formationm of vicinal haloamine products in good yields, the halogen/nitrogensource cheap accessible and easy to operate etc. The result shows that for the ?-nitrostyrene derivatives, the strong electron-donating substituents ?e.g., OCH₃? on the 4-position of benzene ring, it could deactivated the reaction activity, and the yield is relatively lower; whereas strong electron-withdrawing substituents ?e.g., NO₂? could activated reaction activity, and the yield is relatively higher.32 Examples of ?-nitrostyrenes reacted with aliphatic amide and NBS have been investigated in this work and the structure of all new products were confirmed by their corresponding 1H NMR,13C NMR spectra and HRMS?ESI?. 2. The study on the halogen-hydrogen exchange reaction of benzyl dibromo nitromethane with the active methylene compounds Based on the analysing structrural characteristic of the benzyl dibromo nitromethane which bearing multiple strong electron-withdrawing, we guessed that the halogen was a group of easy to leave, but may be a positive ion possible. Thus, we realized that the bromine could be exchanged with hydrogen positive ion. When the benzyl dibromo nitromethane reacted with malononitrile promoted by base, the bromine hydrogen exchanged product was smoothly obtained. For the exploring its generality, a new protocol of bromine hydrogen exchange reaction of benzyl dibromo nitromethane derivatives with active methylene compounds has been developed. The result indicated that for the benzyl dibromo nitromethane derivatives, the strong electron-donating substituents ?e.g., OCH₃? on the 4-position of benzene ring could deactivated the reaction activity, and the yield is relatively lower; whereas strong electron-withdrawing substituents ?e.g., NO₂? could activated reaction activity, and the yield is relatively higher. The bromine hydrogen exchange reaction of 9 examples of benzyl dibromo nitromethane have been investigated in this work and the structure of all products were confirmed by their corresponding 1H NMR,13C NMR spectra and HRMS?ESI?.