A simple strategy for the synthesis of a variety of dihydropyrroles in good to excellent yields via a Lewis acid catalyzed quaternary ammonium salt mediated SN2-type ring-opening followed by cyclization of activated aziridines with alkynes in a domino fashion has been described. The formation and the observed stereoselectivities of the products via an SN2-/double SN2-type ring opening pathway have been rationalized by mechanistic studies.