Synthesis of substituted 2-aminoimidazoles via Pd-catalyzed alkyne carboamination 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 carboamination 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 2-aminoimidazole 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.