Effect of para‐Substituents on meso‐Functionalized Oxidovanadium(IV) Porphyrins as Catalysts for Oxygen Atom Transfer Mediated Oxidation of Benzoin to Benzil under Mild Conditions

Abstract

Systematic analysis of the effect of para‐substituents (H, Cl, Br and OMe) on the meso‐phenyl group in vanadyl meso‐tetraphenylporphyrins ([VIVO(TPP)] (R = H, 1), [VIVO(TCPP)] (R = Cl, 2), [VIVO(TBPP)] (R = Br, 3) and [VIVO(TMPP)] (R = OMe, 4)) on their properties and catalytic oxygen atom transfer (OAT) for oxidation of benzoin to benzil using DMSO as well as 30% aqueous H2O2 as the sacrificial oxygen source have been studied. Electrochemical and theoretical (DFT, density functional theory) study is in good agreement with the influence of these substituents on the catalytic property of these complexes. Complex [VIVO(TCPP)], 2 displayed the best catalytic activity for the conversion (92%) of benzoin to benzil in 30 h with > 99% product selectivity if DMSO was used as an oxygen source, whereas excellent conversion ~ 100%) of benzoin to benzil was noticed in 18 h with 95% product selectivity when 30% aqueous H2O2 was used as a source of oxygen. The structure of 2, 3 and 4, confirmed by single crystal X‐ray diffraction method, are domed in shape, and the displacement of VIV ion from the mean porphyrin plane follows the order: 2 (0.458 Å) < 3 (0.459 Å) < 4 (0.479 Å).

Enhanced Catalytic Activity of Binuclear Oxidovanadium(IV) Bisbenzimidazole Linked Porphyrin Dimer for the Generation of Biologically Active 3,4-Dihydropyrimidinones and Their Corresponding Thiones

“…In recent years, several metalloporphyrins and their analogues, such as metallocorroles, have been employed to be effective and economically viable catalysts for olefin epoxidation, hydrodesulfurization, activation of C–H bonds, benzoin oxidation, oxidative bromination of thymol and phenol derivatives with extremely high TOF values in the aqueous environment. − Due to their diverse applications in the field of catalysis, researchers are trying to explore the catalytic potentials of metalloporphyrins and metallocorroles in different organic transformations.…”

Synthesis of Vanadyl Complexes of N-Confused Porphyrins and Their Bromoperoxidase-like Catalytic Activity

“…To the best of our knowledge, until now, except vanadium, most of the first-row transition metals have been integrated into the core of NCP . Vanadium-, molybdenum-, and manganese- metalated porphyrinoids are frequently employed in catalysis for oxidation reactions such as epoxidation of olefins, oxygen atom transfer, hydroxylation, sulfoxidation, and bromination reactions. − Our group mainly focused on exploiting the catalytic activities of vanadium porphyrinoids for epoxidation of olefins and bromination of phenolic derivatives . For this purpose, we have developed a methodology for the synthesis of vanadyl NCPs, viz., oxido­[5,10,15,20-tetraphenyl-N-confusedporphyrinato]­vanadium­(IV) [VONCP] ( V-1 ) and oxido­[5,10,15,20-tetrakis­(3,5-dimethoxyphenyl)­N-confusedporphyrinato]­vanadium­(IV) [VONCP­(OMe) 8 ] ( V-2 ), for bromination of phenol and its derivatives using the green brominating agents, viz., KBr, H 2 O 2 , and HClO 4 , at room temperature in aqueous media.…”

Highly Efficient β‐Functionalized Oxidomolybdenum(V) Corroles for Catalytic Oxidative Bromination of Phenols at Room Temperature

“…Molybdenum and vanadyl complexes are economical and efficient catalysts for selective oxidative bromination of phenols, epoxidations of olefins, atom transfer and other oxidation reactions [34–39] . Presently, our research group has focused on exploring the catalytic activities of vanadyl porphyrins for olefins epoxidation and oxidative bromination reactions [40–45] .…”