Selective Formation of 2-Imidazolines and 2-Substituted Oxazoles by Using a Three-Component Reaction

Selective formation of 2H‐2‐imidazolines and 2‐substituted oxazoles by using a multicomponent reaction of amines, either aldehydes or ketones, and α‐acidic isocyano amides or esters is described. By selecting the appropriate solvent, AgI or CuI catalyst, or by employing a weak Brønsted acid, the product formation can be fully controlled and directed quantitatively to the desired heterocyclic scaffold. The described experimental procedures not only significantly increase the scope of compatible inputs for this complexity‐generating three‐component reaction, but also allow for considerable chemical diversity: At least four diversity points in two distinct scaffolds can be exploited in this way. One way or the other: Multicomponent reactions of α‐isocyano amides or esters with amines and either aldehydes or ketones can be fully directed towards either oxazole or imidazoline formation. This produces heterocycles with at least four diversity points in two distinct scaffolds (see scheme).