摘要:
(R)-(-)-Ethyl nipecotate 6 was converted into the N-allyl bromide 10 whose derived Grignard reagent 11 was added to N-(phenylsulfonyl)-2-(methoxyoxalyl)indole 12 to give the diastereomeric alcohols 13. Removal of the indole protecting group from 13 and coupling with vindoline gave the separable diastereomers 15(S) and 17(R). Deprotection of 15/17 and treatment with formaldehyde/acetic acid gave desethyldihydronavelbine 5, and its 18'-epimer 19. Only the natural 18'-epimer exhibited any antitumor activity.