REACTIVITY OF NITRILE OXIDES TOWARD THE 5,6-DOUBLE BOND OF URACIL DERIVATIVES - SYNTHESIS OF SOME 5-AROYLPYRIMIDINE NUCLEOSIDE OXIMES

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.