244004-99-7Relevant academic research and scientific papers
Aerobic oxidation reactions catalyzed by vanadium complexes of bis(phenolate) ligands
Zhang, Guoqi,Scott, Brian L.,Wu, Ruilian,Silks, L. A. Pete,Hanson, Susan K.
body text, p. 7354 - 7361 (2012/08/28)
Vanadium(V) complexes of the tridentate bis(phenolate)pyridine ligand H2BPP (H2BPP = 2,6-(HOC6H2-2,4- tBu2)2NC5H3) and the bis(phenolate)amine ligand H2BPA (H2BPA = N,N-bis(2-hydroxy-4,5-dimethylbenzyl)propylamine) have been synthesized and characterized. The ability of the complexes to mediate the oxidative C-C bond cleavage of pinacol was tested. Reaction of the complex (BPP)V V(O)(OiPr) (4) with pinacol afforded the monomeric vanadium(IV) product (BPP)VIV(O)(HOiPr) (6) and acetone. Vanadium(IV) complex 6 was oxidized rapidly by air at room temperature in the presence of NEt3, yielding the vanadium(V) cis-dioxo complex [(BPP)VV(O)2]HNEt3. Complex (BPA)V V(O)(OiPr) (5) reacted with pinacol at room temperature, to afford acetone and the vanadium(IV) dimer [(BPA)VIV(O)(HO iPr)]2. Complexes 4 and 5 were evaluated as catalysts for the aerobic oxidation of 4-methoxybenzyl alcohol and arylglycerol β-aryl ether lignin model compounds. Although both 4 and 5 catalyzed the aerobic oxidation of 4-methoxybenzyl alcohol, complex 4 was found to be a more active and robust catalyst for oxidation of the lignin model compounds. The catalytic activities and selectivities of the bis(phenolate) complexes are compared to previously reported catalysts.
