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4272682 
Journal Article 
Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2and CO2 
Toyao, T; Siddiki, SMAH; Morita, Y; Kamachi, T; Touchy, AS; Onodera, W; Kon, K; Furukawa, S; Ariga, H; Asakura, K; Yoshizawa, K; Shimizu, KI 
2017 
Yes 
Chemistry: A European Journal
ISSN: 0947-6539
EISSN: 1521-3765 
23 
59 
14848-14859 
English 
28815903 
WOS:000413337400022 
Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2and CO2. Initially, Re/TiO2was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3group than to the benzene ring. Moreover, Re/TiO2showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.