Thermal rearrangement of substituted N-acyl-2,2-dimethyl aziridines: a mechanistic study

摘要

The thermolysis of N-acy 1-2,2- dimethyl aziridines 1 yielded N-methallyl amides 2 and/or oxazolines 3 depending on their substitution. These results suggest the intermediate formation of a zwitterion 1' by heterolytic cleavage of the CMe2—N bond of aziridines 1, which could evolve either through hydrogen abstraction from one of the methyl groups or cyclization yielding, respectively, Nmethallyl amides 2 or oxazolines 3. Theoretical calculations by the DFT/B3LYP method confirmed the proposed mechanism for the determination of transition states. The kinetic/thermodynamic competition which governs the formation of the products shows that the oxazoline 3 is the kinetic product and the N-methallyl amide 2 e is the thermodynamic one.