Titanium dioxide as an efficient heterogeneous catalyst for quick C–B bond cleavage of aryl/hetero arylboronic acid on water at room temperature

Template-Less and Surfactant-Less Synthesis of CeO2 Nanostructures for Catalytic Application in Ipso-hydroxylation of Aryl Boronic Acids and the aza-Michael Reaction

“…For example, many reports are available in recent years where more than 1.5 equivalents of H 2 O 2 was used as an oxidizing agent while carrying out the ipso -hydroxylation of aryl boronic acid. 30 , 37 , 42 , 43 Moreover, reports are also available on the ipso -hydroxylation of aryl boronic acids without the use of any oxidizing agent. 38 , 44 However, those protocols require prolonged reaction times and high temperatures, yet the yield of the product is low, which is another disadvantage for commercial use.…”

“…However, most of the traditional synthesis procedures have less substrate scope in terms of yield and require very harsh conditions, such as the requirement of strong bases, high temperature and pressure, and so forth . To overcome those demerits, the ipso -hydroxylation of aryl boronic acids has been adopted in recent times to synthesize phenols due to its various advantages such as the ease of conversion of aryl boronic acids into phenols, nontoxicity, and stability of aryl boronic acids against moisture. , Accordingly, different catalyst systems such as poly­( N -vinylpyrrolidone)-H 2 O 2 and poly­(4-vinyl pyridine)-H 2 O 2 complexes, N -oxide, hypervalent iodine (III), supported Ag nanoparticles (NPs), , graphene oxide, Cu 2 O NPs, ZnO NPs, , and Fe 2 O 3 /Al 2 O 3 nanocomposites have been reported recently by several research groups across the world for the oxidative hydroxylation of aryl boronic acid. In most of the reported protocols involving H 2 O 2 as the oxidant, it has been observed that while trying to make a green catalytic system, they often underestimate the “atom economy” principle of green chemistry.…”

“…In most of the reported protocols involving H 2 O 2 as the oxidant, it has been observed that while trying to make a green catalytic system, they often underestimate the “atom economy” principle of green chemistry. For example, many reports are available in recent years where more than 1.5 equivalents of H 2 O 2 was used as an oxidizing agent while carrying out the ipso -hydroxylation of aryl boronic acid. ,,, Moreover, reports are also available on the ipso -hydroxylation of aryl boronic acids without the use of any oxidizing agent. , However, those protocols require prolonged reaction times and high temperatures, yet the yield of the product is low, which is another disadvantage for commercial use. , Herein, we report the development of a catalyst system for ipso -hydroxylation of boronic acids associated with a high atom economy using CeO 2 nanostructures as reusable catalysts.…”