The present invention provides novel synthetic methods for making acyclic secondary amines by reacting an azide with a compound bearing one or more C—H groups, catalyzed by a FeII-dipyrromethene complex. The acyclic secondary amines are thought to be formed through an intermolecular nitrene transfer. Also provided herein are methods of synthesizing protected (e.g., Boc- or Fmoc-protected) cyclic secondary amines (e.g., 5-, 6-, and 7-membered cyclic secondary amines) by reacting an azide that bears one or more C—H groups, catalyzed by a FeII-dipyrromethene complex. The protected cyclic secondary amines are thought to be formed through an intramolecular nitrene transfer and may be subsequently deprotected to yield cyclic secondary amines.