Iron oligopyridine complexes as efficient catalysts for practical oxidation of arenes, alkanes, tertiary amines and N-acyl cyclic amines with Oxone

The iron complexes [Fe(qpy)](ClO(4))(2) (1) (qpy = 2, 2' : 6', 2 '' : 6 '', 2''' : 6''', 2''''-quinquepyridine), [Fe(2)(spy)(2)](ClO(4))(4) (2) (spy = 2, 2' : 6', 2 '' : 6 '', 2''' : 6''', 2'''': 6'''', 2'''''-sexipyridine), [Fe(2)(septipy)(2)] (ClO(4))(4) (3) (septipy = 2, 2' : 6', 2 '' : 6 '', 2''' : 6''', 2'''' : 6'''', 2''''' : 6''''', 2''''''-septipyridine) and SBA-15-supported iron terpyridine complex (4) are efficient catalysts for the practical oxidation of alkenes, arenes, alkanes, tertiary amines and N-acyl cyclic amines using Oxone as the oxidant. With 1, 2, 3 or 4 as the catalyst, a variety of electron-rich and electron-deficient alkenes were oxidized to the corresponding epoxides in high isolated yields (up to 99%). The reaction of arenes with Oxone afforded quinones in up to 91% isolated yields. Selective C-H bond oxidation of saturated alkanes to alcohols/ketones and demethylation of tertiary amines to secondary amines were achieved in good product yields. For the oxidation of N-acyl cyclic amines, the ring-opened products were obtained in up to 75% isolated yield with up to 96% substrate conversion. All of these iron complexes can efficiently catalyse the oxidative C-C bond cross-coupling reaction of tertiary amines with NaCN in up to 86% isolated yield using ((t)BuO)(2) as the terminal oxidant. The oligopyridine ligands were oxidatively robust and could be re-used by the addition of iron(II) salt to generate the iron catalysts in situ. The active SBA-15-supported terpy ligand could be re-used for the oxidative catalysis for five consecutive runs without significant loss of catalytic activity.