Primary Benzylamines by Efficient N-Alkylation of Benzyl Alcohols Using Commercial Ni Catalysts and Easy-to-Handle Ammonia Sources

Primary benzylamines are highly important building blocks in the pharmaceutical and polymer industry. An attractive catalytic approach to access these compounds is the direct coupling of benzyl alcohols with ammonia via the borrowing hydrogen methodology. However, this approach is usually hampered by a series of side-reactions, one of the most prominent being the overalkylation of the formed primary amine. Herein, we describe a robust catalytic methodology, which utilizes commercially available heterogeneous Ni catalysts and easy-to-handle ammonia sources, such as aqueous ammonia or ammonium salts, for the formation of primary benzylamines with good selectivity and scope. Notably, our method enables the conversion of potentially lignin-derived vanillyl alcohol to vanillylamine, which can be used to produce emerging biobased polymers or as pharma building blocks. Important sugar derived platform alcohols as well as long chain aliphatic primary alcohols can be successfully aminated. Moreover, we provide an alternative, sustainable route to p-xylylenediamine and m-xylylenediamine, important components of heat resistant polyamides such as Kevlar.