Reactivity of 5-hydroxy-5,6-dihydro-4H-pyrazines—easy and efficient access to ring-fused polycyclic diazinic systems

An efficient synthesis of functionalized 1,4-diazinic hemiaminals starting from methyl-4H-1,4-oxazine-3-carboxylate moiety is reported. Given that various polycyclic heterocyclic frameworks could be easily obtained, this strategy may provide an efficient method to access a library of compounds based on privileged substructures that are of interest in drug discovery.