Synthesis of azacycloalkane-1,2-fused pyrroles via alkylation of cyclic ketimines with α-bromo ketones

The reaction of 2-alkyl-substituted 5-, 6- and 7-membered cyclic imines with a-bromo ketones in the presence of Hünig's base affords 2,3-dihydro-1H-pyrrolizines, 5,6,7,8-tetrahydroindolizines and 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines, respectively.