Studies On Transformation Of Benzylic C-H Bond

The catalytic activation of C-H bond and its transformation is one of interesting and important research topics in both fundamental and industrious research. Since benzylic sp³ C-H bond has high chemical reactivity, it can undergo different reactions depending on the reaction conditions, including direct oxidation reaction of C-H bond into carbonyl compound, C-C bond formation through C-H bond activation, and all are highly atom-efficient reactions. In this dissertation, the new catalytic systems for the transformation and formation of benzylic group have been investigated.(1) In the presence of a catalytic amount of K₇NiV₁₃O₃₈·16H₂O, alkyl aromatic compounds could be oxidized into carbonyl compounds by the selective oxidation of benzylic sp³ C-H bond using 30% aqueous H₂O₂ as oxidant, providing a direct oxidation of C-H bond to synthesize carbonyl compounds with green oxidant of hydrogen peroxide.(2) Using PdCl₂ and phosphomolybdic acid (PMA) as combined catalysts, tetraaryl furans could be prepared in one-pot from the reaction of diarylacetylenes with H₂O. The formation of benzyl phenyl ketone from the hydration of diarylacetylene and its oxidative coupling of benzylic C-H bond to give the key intermediate of 1,4-diketone for the formation of furans is proposed as the reasonable route.(3) In the presence of a catalytic amount of InCl₃·4H₂O, trioxane was first used as the methylating agent for multi-methylated aromatic compounds. An efficient and green procedure for the methylation of pentamethylbenzene to afford hexamethylbenzene was developed.(4) An efficient and practical synthesis of diarylmethanes was achieved from the dehydration of electron-rich aromatic compounds with benzyl alcohols in the presence of catalytic amount of InCl₃·4H₂O. The developed procedure is a green procedure, since it is halide-free, and H₂O as the exclusive by-product in the reaction.