We report the discovery, development, and mechanism of a nickel-catalyzed annulation reaction between o-haloarylimines and electron-poor olefins. The reaction produces two adjacent anti stereocenters and a free secondary amine. Spirocycles are formed from cyclic imines. We characterized the key oxidative addition intermediate and identified a major path leading to competing homo-coupling products. The activation energy of oxidative addition, and the rate of oxidative addition complex isomerization were determined. Sensitivity of the reaction to reaction conditions was established in a quantitative manner and both the scope and limitations of the method are presented.