Transamidation reactions. Part 11 . N ‐substituted 3‐aminopropanenitriles and 2‐aminoacetonitriles as Schiff ‐base equivalents

In presence of a strong base, the 13‐membered cyclic compound 3 yielded, by loss of acetonitrile or its equivalent, the bicyclic product 5 instead of the 17‐membered compound 4 as expected (Scheme 2) . Investigation of model compounds (Scheme 4) and of model reactions ( Schemes 5 and 6 ) led to the conclusion that the reaction proceeds via an intermediate formaldehyde imine; a Schiff base, e.g. 3b (Scheme 5) , which reacts intra‐ and intermolecularly with a nucleophile to form a Mannich ‐type product. It seems to be a general principle that N ‐substituted 3‐aminopropanenitrile and 2‐aminoacetonitrile derivatives behave in the presence of a strong base as Schiff ‐base equivalents ( Schemes 5 and 6 ).