Title : Trinuclear Microporous Coordination Polymers as Catalysts for Oxidation of Arylboronic Acids into Phenols
Abstract:
Two isostructural trinuclear coordination polymers (CPs) have been synthesized, characterized and successfully applied as robust heterogeneous catalysts for the oxidation of arylboronic acids into phenols with aqueous hydrogen peroxide (H2O2). The microporous CPs with formulation [M3(bpdc)6(bipy)2].2DMF.2H2O [M = Zn and Mn] are analogous because these two species differ only on the basis of the metal ions present in them and may be termed as isostructural. Each structure consists of two crystallographically distinct M2+ (M1 & M2) centers that are connected via carboxylate bridges from six bpdc ligands, generating a trinuclear metal cluster, [M3(bpdc)6(bipy)2]. Cluster representation of the structure resulted in the interpenetrated net of the rare hex topological type.
Various substituted aryl and hetero arylboronic acids RB(OH)2 [R = phenyl, 3-trifluoromethyl, 4-cyanophenyl etc.] underwent ipso-hydroxylation smoothly at room temperature to provide corresponding phenols in excellent yields. The main advantages of this protocol are the aqueous medium reaction, heterogeneous catalytic system, and short reaction time with excellent yields. All these and other results will be discussed.
