5-烷氧基-3,4-二卤-2(5 H )-呋喃酮与不饱和胺的反应研究

In order to further explore the reactions of 5-alkoxy-3,4-dihalo-2(5H)-furanone with amines, the reactions with a series of unsaturated amines were investigated using KF as catalyst and THF as solvent. Sixteen new beta-amino-2(5H)-furanone products were obtained via the tandem Michael addition-elimination reaction as anticipated in most cases, and their chemical structures and absolute configurations were confirmed via rotation, UV-Vis, IR, H-1 NMR, C-13 NMR, MS, elemental analysis and X-ray single crystal diffraction. However, the reaction between 2,5-dimethyl-3-pyrroline and 5-menthoxy-3,4-dihalo-2(5H)-furanones with larger steric hindrance just yielded unexpected 2(5H)-furanone ring-opening products, while 5-methoxy-3,4-dihalo-2(5H)-furanones with smaller steric hindrance gave both expected beta-amino-2(5H)-furanones and unexpected isomers involving the ring-opening rearrangement mechanism. The latter indicated that the steric hindrance of substrates could affect the reactions and even cause competitive reaction.