Structural Revision of the Hancock Alkaloid (−)-Galipeine

The 1 H and 13 C NMR data of synthetic samples of ( S )- N (1)-methyl-2-[2′-(3″-hydroxy-4″-methoxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline, the originally proposed structure of the Hancock alkaloid (−)-galipeine, do not match those of the natural product. Herein, the preparation of the regioisomer ( S )- N (1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline is reported, the 1 H and 13 C NMR data of which are in excellent agreement with those of (−)-galipeine. Comparison of specific rotation data enables assignment of the absolute ( S )-configuration of the alkaloid, and together, these data engender the structural revision of (−)-galipeine to ( S )- N (1)-methyl-2-[2′-(3″-methoxy-4″-hydroxyphenyl)ethyl]-1,2,3,4-tetrahydroquinoline.