Exo-Selective Intramolecular C–H Alkylation with 1,1-Disubstituted Alkenes by Rare-Earth Catalysts: Construction of Indanes and Tetralins with an All-Carbon Quaternary Center

We report herein the exo-selective,
regiospecific annulation of
a wide range of functionalized aromatic substrates with 1,1-disubstituted
alkenes through C­(sp2)–H and benzylic C­(sp3)–H activation by half-sandwich rare-earth catalysts. This
protocol offers a straightforward and atom-efficient route for the
synthesis of a family of indane and tetralin derivatives bearing an
all-carbon quaternary stereocenter that were difficult to access previously
by other catalysts. The reaction mechanism has been elucidated by
deuterium-labeling experiments and DFT calculations.