1,3-Dipolar cyctoadditions of 4,5-dihydroimidazolium ylides: new protocols for the synthesis of pyrrolidines and pyrrolo[1,2-a]pyrazines

Abstract

1,3-Dipolar cycloadditions of 4,5-dihydroimidazolium ylides formed from 1-benzyl-4,5-dihydroimidazole proceed via a convenient one-step, one-pot protocol to give hexahydropyrrolo[1,2-a]imidazole esters, reduction of which leads to either hexahydropyrrolo[1,2-a]pyrazines or N-substituted pyrrolidines depending on the nature of the ester.