Complete assignments ¹H and¹³C NMR spectral data of four anabaseine derivatives

The anabaseine derivatives 6-methoxy-7-hydroxy-1-(pyridin-3-yl)-3,4- dihydroisoquinoline, 6,7-dimethoxy-1-(pyridin-3-yl)-1,2,3,4- tetrahydroisoqumoline and 6,7-dimethoxy-1-(piperidin-3-yl)-1,2,3,4- tetrahydroisoquinoline were prepared either by demethylation with HBr or by reduction with different reagents, NaBH₄ and H₂/PtO ₂ from 6,7-dimethoxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, as starting material. The structures have been fully assigned by the combination of one- and two-dimensional experiments.