The reaction of hydrazonyl chlorides with 2,3-dichloro-1,4-naphthoquinone yielded pharmaceutically important spiro-naphthalene-1,2'- [1,3,4]oxadiazol-4-ones under batch and flow synthesis methods. The regioselective cycloaddition protocol operates under mild conditions, tolerates a wide range of structural moieties and delivers versatile spiro-oxadiazole motif with high efficiency. The obtained products were elucidated by IR, ¹H NMR, ¹³C NMR, HRMS and compound 6h was characterized by single crystal X-ray diffraction technique. The synthesized molecules have been subjected to theoretical analysis by quantum chemical calculations at DFT/B3LYP/def2-TVZP level, which provided supporting data for the experimental findings. In addition, a concise biological evaluation of some selected novel spirocyclic molecules is reported.