A cobalt–N-heterocyclic carbene catalyst, in combination with neopentylmagnesium bromide, was found to promote ortho-C-H functionalization of 2-arylpyridines with 1,2-diarylaziridines through ring-opening alkylation. The reaction affords 1,1-di- arylethanes bearing 2-amino functional groups in moderate to good yields under mild room-temperature conditions.