N-Heterocyclic carbene-catalyzed enantioselective annulation of 2-amino-1 H -indoles and bromoenals for the synthesis of chiral 2-aryl-2,3-dihydropyrimido[1,2- a ]indol-4 (1 H )-ones.

An efficient N-heterocyclic carbene (NHC)-catalyzed enantioselective [3 + 3] annulation of 2-bromoenals with 2-amino-1 H -indoles has been developed. A series of functionalized 2-aryl-2,3-dihydropyrimido[1,2- a ]indol-4(1 H )-ones were synthesized using NHCs as the catalyst in good yields with high to excellent enantioselectivities.