Highly Chemoselective Reduction of Amides to Amines over a Ruthenium‐Molybdenum Bimetallic Catalyst

Abstract

The chemoselective reduction of amides is important in the synthesis of fine chemicals and inter-mediates. However, the highly stable amide bond due to the orbital overlap between the nitrogen lone pair and the antibonding orbital of the carbonyl group poses a significant limitation in developing suitable heterogeneous catalysts. In this work, we have developed a highly efficient and robust Ru-(0.2)Mo/TiO 2 catalyst for the chemoselective reduction of primary amides. As a consequence, the catalyst afforded 83.1 % conversion with 80 % selectivity of the primary amine after reaction for 12 h for the HDO of cyclohexanecarboxamide at 160 °C. Moreover, the catalyst also presented excellent reusability and substrate diversity. The characterizations of the catalyst revealed that Ru promoted the reduction of Mo 6 + to Mo 5 + and Mo 0 , and the resultant low-coordinated Mo 5 + is responsible for the selective activation of the C=O bond of the amide, while RuMo alloy promoted the activation of hydrogen.

A study of highly activated hydrogen evolution reaction performance in acidic media by 2D heterostructure of N and S doped graphene on MoOx

“…In addition, the increased Mo 5+ peak intensity suggests that the HER activity of the material could be expected to increase because this peak indicates improved conductivity and electrochemical kinetics of the material. 46 The Mo 3d spectrum revealed the presence of multiple oxidation states, Mo 6+ , Mo 5+ , and Mo 4+ , after placing on the GCE. 47 Thus, the enhanced multiple oxidation levels of the MoO x material are likely to facilitate faster electron transfer and increase the HER rate because of its enhanced electrical properties.…”

“…The intensity of the Mo 5+ peak of the NSGr@MoO x heterostructure was higher compared with that of the unprocessed MoO x material, and it could be identified by comparing Figure 1B to Figure . In addition, the increased Mo 5+ peak intensity suggests that the HER activity of the material could be expected to increase because this peak indicates improved conductivity and electrochemical kinetics of the material 46 . The Mo 3d spectrum revealed the presence of multiple oxidation states, Mo 6+ , Mo 5+ , and Mo 4+ , after placing on the GCE 47 .…”

Hydrogenation of amides to amines by heterogeneous catalysis: a review

“…Ru–Mo/TiO 2 catalyst was also found to be highly efficient towards the chemoselective reduction of CyCONH 2 and it could be reused for eight catalytic cycles without significant loss of reactivity and selectivity. 78 In-depth characterization of the catalyst revealed that Ru promotes the reduction of Mo 6+ to Mo 5+ and Mo 0 , and the resultant low-coordinated Mo 5+ was responsible for the selective activation of the amide CO bond, while RuMo alloy promotes the activation of H 2 . Additionally, Ru–W/SiO 2 catalyst was also synthesized, with high activity of 93.6% in CyCONH 2 conversion and 83.7% selectivity to the corresponding primary CyCH 2 NH 2 amine.…”

“…76 Most recently, Wang's group has devoted significant attention to the hydrogenation of CyCONH 2 to CyCH 2 NH 2 , the results being summarized in entries 28-30 of Table 1. [77][78][79] Using identical reaction conditions, they provided a comparison among various catalysts, concluding that the 2Ru1W/SiO 2 catalyst enables the hydrogenation of CyCONH 2 more efficiently in terms of both higher conversion and amine yield, for 93.6% and 84.0%, respectively, than alternative catalysts. However, the turnover frequency based on interfacial Ru-Mo sites was more than twofold higher than that of the Ru-W system.…”