An intramolecular Friedel–Crafts cyclization reaction catalyzed by indium(III) chloride for the formation of 4-vinyl-1,2,3,4-tetrahydroisoquinoline from N-tethered benzyl-alkenol in good yields has been described. The reaction is highly regioselective and generates an exocyclic vinyl functionality in the piperidine ring. The reaction is compatible with a wide range of functional groups. The strategy is demonstrated for the formal synthesis of (±)-isocyclocelabenzine alkaloid.
Key words
tetrahydroisoquinoline - (±)-isocyclocelabenzine - indium(III) chloride - regioselectivity -
N-tethered benzyl-alkenol - Friedel–Crafts