multiple stereocenters from the same set of starting materials. We report herein the first diastereodivergent [3+2] annulation of aromatic aldimines with alkenes via C-H activation by half-sandwich rare-earth catalysts. This protocol provides an efficient and general route for the selective synthesis of both trans and cis diastereoisomers of multi-substituted 1-aminoindanes from the same set of aldimines