Skeletally Diverse Synthesis of Innovative [2,1‑c]‑1,4-Oxazepine and [1,4]-Quinoxaline Systems

An efficient, innovative synthesis of [2,1-c]-1, 4-oxazepine and [1,4]-quinoxaline heterocycles along with the embodied pyrimido-pyrrolo motifs was established. Initially, the pyrrole ring was installed using microwave irradiation through an intramolecular base-catalyzed cyclization between acetyl bromomethyl pyrimidine dione and o-amino phenyl methanol or o-phenylenediamine methyl benzoates. Furthermore, oxazepine, and quinoxaline scaffolds were constructed by an acid-catalyzed condensation with a variety of aldehydes by an unconventional Pictet–Spengler reaction strategy. An important aspect of this work is to build novel heterocyclic ring systems with potential medicinal interest.