合成路线1

Mitsunobu coupling between tryptophol (XVII) and sulfonamide (VIII) yields the N-sulfonyl tryptamine derivative (XVIII). Hydration of the cyclic enol ether, with simultaneous Boc group cleavage under acidic conditions affords lactol (XIX). Subsequent deprotection of the dinitrobenzenesulfonyl group of (XIX) with piperidine in MeOH proceeds with rearrangement of the deprotected amino lactol to the cyclic hydroxy enamine (XX). This, upon further heating, undergoes a Diels-Alder type reaction to afford the pentacyclic vindoline ring system (XXI). Following a previously reported synthetic pathway for (XXI), regioselective elimination of the secondary alcohol function, followed by protective group exchange at the phenolic hydroxyl, and oxidation with benzeneseleninic anhydride leads to the C4-alcohol (XXII). Further introduction of the C3-hydroxyl with m chloroperbenzoic acid, and reduction of the resultant imine with NaBH3CN provides diol (XXIII). After reductive methylation of the indoline N of (XXIII) with HCHO/NaBH3CN, acetylation of the secondary hydroxyl group produces ( ) vindoline (XXIII) (8, 9).