Au(I)-Catalyzed Annulation of Propargyl Amine with Aldehydes: One-Pot Cascade Synthesis of 2,5-Dimethylpyrazines

3-Substituted 2,5-dimethylpyrazines were synthesized in high yields via a one-pot cascade annulation of easily available propargyl amine with aldehydes catalyzed by Au(PPh2Cy)Cl.