Hydroboration of unsaturated organic molecules is a fundamental transformation in synthetic organic chemistry relevant to the production of both commodity and fine chemical products. In contrast to alkyl and aryl boranes, which are known to add to multiple carbon-carbon and carbon-heteroatom bonds easily, the use of deactivated boranes, such as HBPin, requires the application of transition metal catalysts, majority of which are based on heavy late transition metals (Rh, Ir, etc). Due to the skyrocketing prices of these metals, the development of hydroboration catalysts based on more economical base metal systems (Fe, Co, Ni) has become an attractive area of research in the last decade. One of the most popular ligand platforms for the design of such systems is pincer type ligands. The rigid nature and easily tunable steric and electronic properties of such ligands provide a unique balance of stability <i>vs</i> reactivity for pincer complexes, often enhancing the selectivity of catalytic reactions.<br/>Here we report the preparation, characterization, and reactivity studies of novel Ni(II) pincer complexes with iminophosphinite POCN ligands derived from 3-hydroxybenzaldehyde. Such complexes serve as pre-catalysts for efficient hydroboration of carbonyl compounds, including the first example of hydroborative reduction of tertiary, secondary and primary amides to the corresponding amines. Moreover, hydroboration of aldehydes can be performed chemoselectively in the presence of compounds having other potent reductive functional groups.

Efficient hydroboration of carbonyl compounds with iminophosphinite POCN pincer complexes of nickel

2019 Spring National Meeting

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