Easy Access to New Heterocyclic Systems:  1,4-Oxazine and Substituted 1,4-Oxazines

In the course of our investigations on the synthesis of new nitrogen heterocyclic derivatives, we were interested in the synthesis and study of new 1,4-oxazine rings. To this aim, the desired bisvinylphosphate was prepared from N-Boc morpholine-3,5-dione and was then engaged in palladium-catalyzed reactions (reduction, Suzuki, and Stille cross-coupling reactions). The 1,4-oxazine and its corresponding 3,5-disubstituted derivatives were obtained in fair to good yields and were then functionalized under anionic conditions.