Vanadium Aminophenolate Complexes and Their Catalytic Activity in Aerobic and H2O2‐Mediated Oxidation Reactions

Vanadium compounds supported by tetradentate amino-bis(phenolate) ligands, [VO(OMe)(O2NOBuMeMeth)] (1), [VO(OMe)(ON2OBuMe)] (2), [VO(OMe)(O2NNBuBuPy)] (3), and [VO(OMe)(O2NOBuBuFurf)] (4) [where (O2NOBuMeMeth) = MeOCH2CH2N(CH2ArOH)2, Ar = 3,5-C6H2-Me, tBu; (ON2OBuMe) = HOArCH2NMeCH2CH2NMeCH2ArOH, Ar = 3,5-C6H2-Me, tBu; (O2NNBuBuPy) = C5H4NCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2; (O2NOBuBuFurf) = C4H3OCH2N(CH2ArOH)2, Ar = 3,5-C6H2-tBu2] were synthesized and characterized by NMR spectroscopy, MALDI-TOF mass spectrometry and UV/Vis data. The catalytic activity of 1–4 as homogeneous catalysts in the aerobic oxidation of 4-methoxybenzyl alcohol and 1,2-diphenyl-2-methoxyethanol was explored. 1 and 2 showed moderately superior activity compared with 3 and 4, which might be due to increased stability of these complexes. 1–4 showed limited reactivity in H2O2-mediated oxidation of diphenyl ether and benzyl phenyl ether.