Annulation of Aromatic Imines via Directed C−H Bond Activation

A directed C−H bond activation approach to the synthesis of indans, tetralins, dihydrofurans,
dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic
ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the
imine directing group has been achieved using (PPh3)3RhCl (Wilkinson's catalyst). The cyclization
of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good
regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling
of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.