A cascade cyclization involving union of three imines by an organocatalyst proline is established to afford new fused-tetrahydroimidazo[1,5-c]imidazol-7- ones with excellent regio- and stereoselectivity. Another dehydrogenative cyclization by union of two imines is developed using the Cu(OTf) 2-Ag 2O combo catalyst to furnish functionalized imidazoles. © 2012 The Royal Society of Chemistry.