Synthesis of Isoindoles and Isoquinolines via 1,3-Dipolar Cycloaddition and Electrocyclization

Significance

Reported is a two-step sequence for the synthesis of isoindoles from α-azido carbonyl compounds containing a 2-alkenylaryl unit via 1,3-dipolar cycloaddition of azide onto the tethered alkene. It was also realized that the synthesis of dihydroisoquinolines can be achieved from the same starting mesylate by reacting it with NaN₃, then with base (K₂CO₃) in EtOH (as proton source) followed by 6π-electrocyclization under dilution in toluene. Some of the dihydroisoquinolines gave the corresponding isoquinoline derivatives under aerial oxidation.