Abstract:

2-Oxazoline derivative belongs to an important class of heterocyclic compounds, new synthetic method and new 2-oxazoline derivatives are eagerly desired. In order to develop a new protocol for the synthesis of deferent structural 2-oxazoline derivatives, a method from ethyl α-cyanocinnamate derivatives and N-bromobenzamide has been explored. The structures of all eleven synthesized products were confirmed by proton nuclear magnetic resonance spectroscopy(¹H NMR), and mass spectrometry(MS). The results show that a series of ethyl α-cyanocinnamate derivatives(3a~3k) can be smoothly converted into corresponding 2-oxazoline derivatives(5a~5k). When Na₂CO₃ was used as the promoter in acetone at room temperature, the corresponding products were obtained in high yield(up to 90%). Not only can ethyl α-cyanocinnamate derivatives be used as substrate, but also ethyl α-carbethoxy-cyanocinnamate(6) can be employed as the substrate, too. Experiment results indicate that N-bromo-p-nitrobenzamide(8) and N-bromoacetamide(9) can tolerate this reaction except N-bromobenzamide(4). Above results indicate that the easy and efficient protocol has application in a large scope of electron-deficient olefins and N-bromoamide. A possible mechanism was proposed which can explain well the full regiospecificity of the reaction.

Key words: ethyl α-cyanocinnamate, N-bromobenzamide, oxazoline derivative