Reported herein is a new iron-catalyzed diastereoselective olefin diazidation reaction which occurs at room temperature (1-5 mol% of catalysts and d.r. values of up to >20:1). This method tolerates a broad range of both unfunctionalized and highly functionalized olefins, including those that are incompatible with existing methods. It also provides a convenient approach to vicinal primary diamines as well as other synthetically valuable nitrogen-containing building blocks which are difficult to obtain with alternative methods. Preliminary mechanistic studies suggest that the reaction may proceed through a new mechanistic pathway in which both Lewis acid activation and iron-enabled redox-catalysis are crucial for selective azido-group transfer.