Nucleophilic Addition onto Methyl-4<i>H</i>-1,4-oxazine-3-carboxylate Moiety: Short Access to 1,4-Diazine Privileged Substructures

To determine the synthetic potential of the original 1,4-oxazine ring, which appears as a valuable building block for the synthesis of more complex derivatives, Michael-type nucleophilic additions were studied. According to the nature of the nucleophile, either acyclic or cyclic derivatives were isolated. In the presence of primary amines, a short and efficient access to diazinic hemiaminals was described.