Synthesis and structural determination of 5H-benzocyclohepten-5,8-imines

Treatment of 4-hydroxy-N-methylisoquinolinium iodide with triethylamine in tetrahydrofuran or acetonitrile forms 2-methyl-4-oxidoisoquinolinium ( 2 ) in situ. Once formed, 2 can be trapped with dipolarophiles possessing varying degrees of activation to form the 5H-benzocyclohepten-5,8-imine ring system. Various 2-D nmr experiments were used in the identification of the stereochemical and regiochemical assignments for the ring system.