Structural Revision of the Hancock Alkaloid (−)-Galipeine

The ¹H and ¹³C 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 ¹H and ¹³C 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.