Selective Transfer Hydrogenation of Aldehydes and Ketones Catalyzed by an
Aminophosphinite POCN H Pincer Complex of Ni(II)
Dinmukhamed Shakhman
Department of Chemistry, School of Science and Humanities,
Nazarbayev University, Nur-Sultan, Kazakhstan
Email: [email protected]
Abstract
The novel secondary aminophosphinite pincer ligand and the corresponding nickel bromide pre – catalyst
A (POCN H )NiBr have been developed and subjected to catalytic transfer hydrogenation (TH) of various
aldehydes and ketones. The fact that isopropanol was used as both hydrogen donor and reaction media
allows for operational simplicity, reduced cost and enhanced safety of those transformations due to an easy
access to hydrogen sources and the absence of the need for high hydrogen pressures. Substrates bearing
both electron – donating and withdrawing functionalities were efficiently reduced to the corresponding
alcohols in good yields. Generally, higher conversions were observed in TH of ketones compared to
aldehydes. Preliminary mechanistic studies suggest that transfer hydrogenation in this study proceeds via
outer sphere route based on the metal – ligand cooperativity, and occurs through Ni hydride specie
formation. This demonstrates the novelty of our approach, since a large number of transition metal
complexes, including non – precious metal compounds, have been reported to catalyze TH of aldehydes
and ketones via metal – centered inner sphere pathway.
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