A new pyrrolo[1,2-a]pyrazine chemical space with a poly-substituted pyrazine unit was readily accessed by Sc(OTf)3-catalyzed one-pot three-component coupling of a pyrrole derivative, amine, and trialkylphosphite under environment-friendly conditions. The formation of multiple bonds (two C-N and one C-P) via a domino process consisting of the chemoselective Kabachnik-Fields reaction and intramolecular cyclodehydration allowed for the construction of highly functionalized pyrazines.