Use of Lanthanide(III) Ions as Catalysts for the Reactions of Amines with Nitriles

Article abstract of DOI:10.1021/jo00382a009

Catalytic amounts of lanthanide(III) triflates promote reactions between amines and nitriles leading to a variety of products.The Ln³⁺ ions activate weakly coordinating nitriles at large amine: Ln³⁺ mole ratios, even in the presence of amines that form thermodynamically stable complexes with Ln³⁺ ions.The reactions involving primary monoamines and diamines appear to be general and provide a viable synthetic route to N,N'-disubstituted amidines (2) and cyclic amidines (4), respectively.Symmetrically substituted triazines (8 or 9) are observed as byproducts in some of these systems when the reactions are carried out by using excess nitrile.Secondary alicyclic amines or dimethylamine reacts with acetonitrile to yield pyrimidines (6) and 2,4,6-trimethyl-s-triazine (8).Two routes to triazine have been proposed, one involving the reaction of ammonia with the nitrile and the second involving the reaction of an amidine (1 or 5) with the nitrile.The ability of Ln³⁺ ions to activate nitriles under conditions that oppose nitrile coordination is attributed to the lability of Ln³⁺ complexes derived from N-donors.