The impact of the nature of amine reactants in the palladium catalyzed conversion of phenol to N-substituted anilines

Anilines and cyclohexylamines are currently produced from fossil feedstocks. Phenol would be an attractive alternative feedstock that can be obtained from renewable resources. We herein clarify the influence of the amine on the course of the amination of phenol using a hydrogen borrowing strategy. Amines can in this case act as a reductant which can be dehydrogenated to initiate the partial hydrogenation of phenol which is required for the reaction to take place. The nature of the amine reactant can have a larger effect than the presence of additional reductants like sodium formate. The results in this report do not only present a method for the amination of phenol without addition of an extra reductant, but also rationalize the reactivity of amines in their reaction with phenol.