Alangiside, the monoterpenoid alkaloidal glycoside from Alangium lamarckii Thw.

Abstract

The structure and absolute configuration of O-methylalangiside (15){11-(β-D-glycopyranosyloxy)-5,11,12,12a,13,13a-hexahydro-2,3-dimethoxy-12-vinyl-6H-benzo[a]pyrano[3,4-g]quinolizin-8-one} has been established by chemical and spectroscopic studies and by correlation with ipecoside. Synthetic evidence is presented which indirectly confirms the 3-methoxy-(11) rather than the 2-methoxy-structure (12) for alangiside.