Abstarct: The pyrazine nucleus which is present in many pharmaceuticals exhibit a broad spectrum of biological activities such as antibacterial, antiglucoma, and antiproliferative properties. In this work an efficent synthesis of [2,3-b]pyrrolopyrazines through palladium–catalyzed heteroannulation is reported. The reaction of 5,6-dichloro pyrazine-2,3-dicarbonitrile (20) with various primary alkylamines in tetrahydrofuran affords 5-alkyl(aryl)amino-6-chloropyrazine-2,3-dicarbonitrile (36a-h) in high yield. When compounds (36a-h) were treated with aromatic terminal alkynes in water in the presence of palladium(II)chloride and cuprous(I)iodide at 70ºC, new drivatives of 5-alkyl(aryl)-6-phenyl-5H-pyrrolo[2,3-b]pyrazine-2,3-dicarbonitril (86a-h) were obtained in good to high yields. In this reaction witch was carried out under an argon atmosphere, potassium carbonate acted as a baxse. In the proposed mechanism for this reaction, the Pd(0) is formed in situ from the added catalyst. The structure of products were established by spectroscopic method. In conclusion the described method for the synthesis of N-substituted pyrrolopyrazines is an easy one-pot procedure which gave rise to good to high yields of the desired products, and water was used as a cheap and more importantly ecofriendly solvent.