Comformational Difference between Erythrinan- and Homoerythrinan-3-ones: Total Synthesis of (±)-Schelhammeridine and (±)-3-Epischelhammeridine

Erythrinan- and homoerythrinan-3-ones behave differently toward hydride reductions suggesting their conformational difference: for example, Δ 1 -erythrinan-3-one gives 3α-alcohol and Δ 1 -homoerythrinan-3-one gives 3β-alcohol stereoselectively on reduction with NaBH 4 -CeCl 3 in methanol. Based on these observations, total syntheses of homoerythrinan alkaloids, schelhammeridine and 3-epischelhammeridine, and an erythrinan alkaloid, 8-oxoerysotrine, were accomplished