Rhodium(II) acetate catalyzed reactions of various substituted 3-diazopiperidin-2-ones with a range of aromatic amines, indoles, and benzotriazole yield exclusively the corresponding N–H insertion products despite competing C-H or O-H insertions. This strategy provides an example of a facile chemoselective N–H insertion reaction delivering a library of 3-arylamino and 3-heteroarylpiperidin-2-one derivatives