An Enantioselective Total Synthesis of (+)-Geissoschizine
作者:Stephen F. Martin、Kevin X. Chen、C. Todd Eary
DOI:10.1021/ol990554a
日期:1999.7.1
[formula: see text] A concise asymmetric synthesis of the indole alkaloid (+)-geissoschizine (1) has been completed. The synthesis features the highly diastereoselective vinylogous Mannich reaction of 3 with 4 to give 5, which is elaborated into the key tetracyclic intermediate 7 in two steps. Following the stereoselective introduction of the ethylidene moiety to give 9, reduction of the lactam and
Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Total Synthesis of (−)-17-nor-Excelsinidine
作者:Maxime Jarret、Aurélien Tap、Cyrille Kouklovsky、Erwan Poupon、Laurent Evanno、Guillaume Vincent
DOI:10.1002/anie.201802610
日期:2018.9.17
report the first totalsynthesis of (−)‐17‐nor‐excelsinidine, a zwitterionic monoterpene indole alkaloid that displays an unusual N4−C16 connection. Inspired by the postulated biosynthesis, we explored an oxidative coupling approach from the geissoschizine framework to forge the key ammonium–acetate connection. Two strategies allowed us to achieve this goal, namely an intramolecular nucleophilic substitution
Biomimetic Entry to the Sarpagan Family of Indole Alkaloids: Total Synthesis of (+)-Geissoschizine and (+)-<i>N</i>-Methylvellosimine
作者:Alexander Deiters、Kevin Chen、C. Todd Eary、Stephen F. Martin
DOI:10.1021/ja0296024
日期:2003.4.1
(+)-geissoschizine (1) by formylation. The common intermediate 27 was then converted via a straightforward sequence of reactions into the alpha-amino nitrile 39. The derived silyl enolether 40 underwent ionization upon exposure to BF(3).OEt(2) to give the intermediate iminium ion 41 that then cyclized in a biomimetically inspired intramolecular Mannich reaction to deliver (+)-N(a)-methylvellosimine (5). This transformation
Bioinspired Divergent Oxidative Cyclizations of Geissoschizine: Total Synthesis of (–)‐17‐nor‐Excelsinidine, (+)‐16‐
<i>epi</i>
‐Pleiocarpamine, (+)‐16‐Hydroxymethyl‐Pleiocarpamine and (+)‐Taberdivarine H
作者:Maxime Jarret、Aurélien Tap、Victor Turpin、Natacha Denizot、Cyrille Kouklovsky、Erwan Poupon、Laurent Evanno、Guillaume Vincent
DOI:10.1002/ejoc.202000962
日期:2020.10.31
To synthesize excelsinidines and mavacurans alkaloids, bio‐inspired oxidativecyclizations of (+)‐geissochizine and analogues mediated by KHMDS/I2 were studied. Applied to geissoschizine, the N4–C16 bond formation led to excelsinidines core. Quaternization of the aliphatic nitrogen was necessary to access the mavacurans core (N1–C16 bond). Alternatively, 17‐nor‐excelsinidine was synthetized via an
为了合成excelsinidines和mavacurans生物碱,研究了由KHMDS / I 2介导的(+)-geissochizine及其类似物的生物启发性氧化环化作用。应用于Geissoschizine时,N4-C16键的形成导致了Excelsinidines的核心。脂族氮的季铵化是进入马六甲聚糖核心(N1-C16键)所必需的。或者,通过α-氯内酰胺的分子内亲核取代合成17-或excelsinidine。
Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for Enantioselective Total Synthesis of Mavacuran Alkaloids
Reported is the enantioselective total syntheses of mavacuran alkaloids, (+)‐taberdivarineH, (+)‐16‐hydroxymethyl‐pleiocarpamine, and (+)‐16‐epi‐pleiocarpamine, and their postulated biosynthetic precursor 16‐formyl‐pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired
报道了马卡武兰生物碱,(+)-二萜H,(+)-16-羟甲基-pleiocarpamine和(+)-16- epi -pleiocarpamine及其假定的生物合成前体16-formyl -pleiocarpamine的对映体选择性合成。该单萜吲哚生物碱家族是一个选择的目标,因为它的某些成员是复杂的双吲哚生物碱的亚基,例如双叶茶碱。受生物合成假说的启发,探索了从Geissoschizine框架形成N1-C16键的氧化偶联方法。脂族氮中心的季铵化是实现KHMDS / I 2诱导的氧化偶联的关键,因为它掩盖了脂族氮中心的亲核性并锁定了所需的顺式构象。