Enhancing the efficiency of the ruthenium catalysts in the reductive amination without an external hydrogen source

Syngas Instead of Hydrogen Gas as a Reducing Agent─A Strategy To Improve the Selectivity and Efficiency of Organometallic Catalysts

“…Another way to improve the selectivity of reaction is to change the reducing agent. For example, carbon monoxide is a promising alternative to hydrogen. − Such reactions using CO proceed via reductive deoxygenation without an external hydrogen source, providing a higher selectivity, at the expense of a generally lower activity …”

“…More complicated rhodium catalysts led to a TON of 1340. Catalysts based on metals such as Ru, , Ir, , and Os , can also be used for the reductive amination reaction involving CO. Herein, application of Rh 2 (esp) 2 or Rh 2 (OAc) 4 with syngas gives much higher values of TON, demonstrating excellent perspectives of this reducing agent.…”

“…Aldehydes with electron-donating groups provided slightly higher yields (17, 18, 20, 22, and 25) than those with electron-withdrawing groups (21) due to the mesomeric effect, which can also explain the different reactivity of para- (18) and ortho-(20) vs meta- (19) substituted aldehydes. Moreover, various functional groups, including carbonyl (21), bromo (22), O-benzyl (25), and cyano (17−26) moieties, were well tolerated, and TONs of 3503−4772 were observed. In order to further confirm the superior performance of the developed syngas-based reducing system over that of hydrogen gas, we tested its applicability to reduction reactions catalyzed by other metal complexes.…”

Fluoride Additive as a Simple Tool to Qualitatively Improve Performance of Nickel-Catalyzed Asymmetric Michael Addition of Malonates to Nitroolefins

“…Development of highly efficient and available catalytic systems is a great challenge to overcome by the catalytic community, and research in this field is on the cutting edge of the modern chemistry. − Currently, the main trend to obtain a high-performance chemical transformation is preparation of new and progressively more complicated catalysts aiming at increasing their selectivity and activity. However, this results in the low availability of these catalysts to the synthetic community. , Hence, novel approaches toward simple catalysts with high activity and selectivity are highly desirable.…”

“…However, this results in the low availability of these catalysts to the synthetic community. 6,7 Hence, novel approaches toward simple catalysts with high activity and selectivity are highly desirable.…”