Studies in biomimetic alkaloid syntheses. 5. Studies syntheses of .psi.-vincadifformine, 20-epi-.psi.-vincadifformine, pandoline, 20-epipandoline, and the C-16 epimeric(carbomethoxy)velbanamines
Studies in biomimetic alkaloid syntheses. 8. Total syntheses of the C-14 epimeric hydroxyvincadifformines, tabersonine, a (hydroxymethyl)-D-norvincadifformine and the C-20 epimeric pandolines