Diastereodivergent [3 + 2] Annulation of Aromatic Aldimines with Alkenes via C–H Activation by Half-Sandwich Rare-Earth Catalysts

Stereodivergent
catalysis is of great importance, as it can allow
efficient access to all possible stereoisomers of a given product
with 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 multisubstituted 1-aminoindanes
from the same set of aldimines and alkenes, featuring 100% atom efficiency,
excellent diastereoselectivity, broad substrate scope, and good functional
group compatibility. The diastereodivergence is achieved by fine-tuning
the sterics or ligand/metal combination of the half-sandwich rare-earth
metal complexes.