Reactivity of nitrile oxides toward the 5,6-double bond of uracil derivatives: synthesis of some 5-aroylpyrimidine nucleoside oximes
摘要:
The 5-aroylpyrimidine nucleoside oximes 3-10 were prepared in moderate to good yield by the reaction of the corresponding pyrimidine nucleosides 2a-d with stable nitrile oxides. The nitrile oxides were generated in situ from the corresponding hydroximoyl chlorides 1a-e. From these reactions, only the 1,3-addition products 3-10 were obtained. No products of cycloaddition could be isolated. The 1,3-addition products 3-10 could be formed from the ring-opening reaction of the initially formed 1,3-cycloaddition products. Evidence that supports the proposed mechanism came from experiments that used 1,3-dimethyluracil (13) as the substrate.