Facile cyclization in the synthesis of highly fused diaza cyclooctanoid compounds using retrievable nano magnetite-supported sulfonic acid catalyst

Magnetically separable Fe3O4-SO3H nano particles have been prepared and established as an efficient catalyst for the synthesis of dihydrofuran fused cyclooctanoids via the dehydration reaction of dihydroxy cyclooctanoid heterocylces. Nanomagnetite, Fe3O4-SO3H was prepared using an impregnation protocol and fully characterized by XRD, FT-IR, TEM, and FE-SEM-EDS. The catalyst was recycled for five consecutive cycles with almost unaltered catalytic activity. The dehydration step was performed keeping the acid sensitive amide linkage intact under ambient temperature and milder reaction conditions. The efficacy of the methodology lies in the excellent yield of product formation within a short span of reaction time avoiding undesirable side products due to the substrate decomposition by ring rupture and tedious purification and work-up procedure.