Polyhydroxylated pyrrolizidine alkaloids from transannular iodoaminations: application to the asymmetric syntheses of (−)-hyacinthacine A1, (−)-7a-epi-hyacinthacine A1, (−)-hyacinthacine A2, and (−)-1-epi-alexine
作者:E. Anne Brock、Stephen G. Davies、James A. Lee、Paul M. Roberts、James E. Thomson
DOI:10.1039/c3ob40205c
日期:——
N-substituent) were readily prepared via conjugate addition of lithium (R)-N-but-3-enyl-N-(α-methyl-p-methoxybenzyl)amide to either tert-butyl (4S,5R,E)-4,5-dihydroxy-4,5-O-isopropylidene-2,7-dienoate (derived from D-ribose) or tert-butyl (S,S,E)-4,5-dihydroxy-4,5-O-isopropylidene-2,7-dienoate (derived from L-tartaric acid) coupled with in situ enolate oxidation with (−)-camphorsulfonyloxaziridine, followed
取代的1,2,3,4,7,8-六氢偶氮cine碱支架的跨环碘代胺化已发展成为一种多用途,非对映异构的途径,从而能够合成一系列吡咯并idine啶生物碱,如(-)-乙酰丁胺碱的合成所证明的那样A1,( - ) - 7a-图外延-hyacinthacine A1,( - ) - hyacinthacine A2,和( - ) - 1-外延-alexine。必要的1,2,3,4,7,8-六氢偶氮cine碱(带有N -α-甲基-对甲氧基苄基或无N-取代基)可以通过共轭加成(R)-N-丁-3-烯基-N-(α-甲基-对甲氧基苄基)酰胺锂要么叔丁基(4小号,5 - [R ,ê)-4,5-二羟基-4,5- ö异亚丙基-2,7-二烯酸酯(衍生自D-核糖)或叔丁基(S,S,E)-4,5-二羟基-4,5- O-异亚丙基-2,7-二烯酸酯(衍生自L-酒石酸),再用(-)-樟脑磺酰基恶二丙啶原位烯醇氧化,然后用Grubbs