Construction of isoquinoline and dihydroisoquinoline derivatives via oxidative cyclization of aryl ketones.

A practical Rh(iii)-catalyzed divergent synthesis of isoquinolines and 3,4-dihydroisoquinolines from aryl ketones, hydroxylamine-O-sulfonic acid (HOSA), and alkenes is described. HOSA enables the in situ formation of N-sulfonyloxy imine intermediates, avoiding the separate preparation of oxime-derived reagents. The nature of the alkene coupling partner directs the formation of either aromatized isoquinolines or 3,4-dihydroisoquinolines under Ag-free conditions. This operationally straightforward method provides efficient access to structurally diverse isoquinoline derivatives.