New regiocontrolled syntheses of pyrrolopyrazinones and its application to the synthesis of peramine

Two novel regiocontrolled syntheses of pyrrolopyrazinones were developed. N-Methylpyrrole amide and 1-bromo-1-alkyne were annulated in the presence of a copper catalyst to give 3-substituted pyrrolopyrazinone in a regioselective manner. In contrast, heating N-methylpyrrole amide with the same haloalkyne in the presence of K3PO4 provided the haloaminal, which was transformed regioselectively into 4-substituted pyrrolopyrazinone. The former procedure was successfully applied to the synthesis of peramine, a natural product isolated from an endophytic fungus.

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