In Situ Generated Cobalt Catalyst for the Dehydrogenative Coupling of Alcohols and Amines into Imines

An in situ formed cobalt catalyst is developed from cobalt(II)bromide, bis[2-(diisopropylphosphino)-4-methylphenyl]amine and zinc metal. The catalyst mediates the acceptorless dehydrogenative coupling of alcohols and amines into imines with the release of hydrogen gas and the transformation is applied to the synthesis of a variety of imines from different alcohols and amines.

The mechanism is investigated with labelled substrates and based on the results a cobalt(I) PNP complex is believed to be the catalytically active species which abstracts hydrogen gas from the alcohol through a metal ligand bifunctional pathway.