Synthesis of Substituted 2-Aminoimidazoles via Pd-Catalyzed Alkyne Carboannination Reactions. Application to the Synthesis of Preclathridine Natural Products

A new method for the synthesis of 2-aminoimidazole products is described. The heterocyclic products are generated in good yields via Pd-catalyzed carboatnination reactions of N-propargyl guanidines and aryl triflates. This methodology generates both a C-N and C-C bond during the annulation step and facilitates the rapid construction of 2aminoimidazole products with different aryl groups. The utility of this methodology was demonstrated in the total synthesis of preclathridine A, preclathridine B, and dorimidazole B from a single intermediate.