scholarly journals Bioinspired Divergent Oxidative Cyclization of Strictosidine and Vincoside Derivatives: Second Generation Enantioselective Total Synthesis of (–)-Cymoside

2020 ◽  
Author(s):  
Yingchao Dou ◽  
Cyrille Kouklovsky ◽  
Guillaume Vincent
Keyword(s):  
Total Synthesis ◽  
Second Generation ◽  
Oxidative Cyclization ◽  
Enol Ether ◽  
Enantioselective Total Synthesis ◽  
Terminal Alkene

<p>We report our second generation synthesis of (–)-cymoside as well as the formation of a new hexacyclic-fused furo[3,2-<i>b</i>]indoline framework. After a Pictet-Spengler condensation between secologanin tetraacetate and tryptamine, the course of the cyclization of the 7-hydroxyindolenine intermediate generated by oxidation with an oxaziridine, depends on the stereochemistry of the 3-position. The 3<i>-(S)-</i>strictosidine stereochemistry delivered efficiently the scaffold of cymoside via intramolecular coupling with the C16-C17 enol ether, while the 3<i>-(R)-</i>vincoside stereochemistry directed towards the reaction with the C18-C19 terminal alkene and the formation of the unexpected caged compound.</p>

scholarly journals Bioinspired Divergent Oxidative Cyclization of Strictosidine and Vincoside Derivatives: Second Generation Enantioselective Total Synthesis of (–)-Cymoside

2020 ◽  
Author(s):  
Yingchao Dou ◽  
Cyrille Kouklovsky ◽  
Guillaume Vincent
Keyword(s):  
Total Synthesis ◽  
Second Generation ◽  
Oxidative Cyclization ◽  
Enol Ether ◽  
Enantioselective Total Synthesis ◽  
Terminal Alkene

<p>We report our second generation synthesis of (–)-cymoside as well as the formation of a new hexacyclic-fused furo[3,2-<i>b</i>]indoline framework. After a Pictet-Spengler condensation between secologanin tetraacetate and tryptamine, the course of the cyclization of the 7-hydroxyindolenine intermediate generated by oxidation with an oxaziridine, depends on the stereochemistry of the 3-position. The 3<i>-(S)-</i>strictosidine stereochemistry delivered efficiently the scaffold of cymoside via intramolecular coupling with the C16-C17 enol ether, while the 3<i>-(R)-</i>vincoside stereochemistry directed towards the reaction with the C18-C19 terminal alkene and the formation of the unexpected caged compound.</p>

scholarly journals Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Enantioselective Total Synthesis of Mavacuran Alkaloids

2019 ◽  
Author(s):  
Maxime Jarret ◽  
Victor Turpin ◽  
Aurélien Tap ◽  
Jean-Francois Gallard ◽  
Cyrille Kouklovsky ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Oxidative Coupling ◽  
Indole Alkaloids ◽  
Oxidative Cyclization ◽  
Total Syntheses ◽  
Enantioselective Total Synthesis ◽  
Biosynthetic Precursor ◽  
Monoterpene Indole Alkaloids ◽  
Coupling Approach

We report the enantioselective total syntheses of mavacurans alkaloids, (+)-taberdivarine H, (+)-16-hydoxymethyl-pleiocarpamine, (+)-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 by the biosynthetic hypothesis, we explored an oxidative coupling approach from the geissoschizine framework to form the N1-C16 bond. Quaternization of the aliphatic nitrogen was key to achieve the oxidative coupling induced by KHMDS/I<sub>2 </sub>since<sub> </sub>it hides the nucleophilicity of the aliphatic nitrogen and locks the required cis conformation.

scholarly journals Enantioselective Total Synthesis of Cymoside through a Bioinspired Oxidative Cyclization of a Strictosidine Derivative

2019 ◽  
Vol 132 (4) ◽  
pp. 1543-1547 ◽  
Author(s):  
Yingchao Dou ◽  
Cyrille Kouklovsky ◽  
Vincent Gandon ◽  
Guillaume Vincent
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Enantioselective Total Synthesis

A New Enantioselective Total Synthesis of Natural Vincamineviaan IntramolecularMannichReaction of an Silyl Enol Ether

1977 ◽  
Vol 60 (5) ◽  
pp. 1801-1810 ◽  
Author(s):  
Wolfgang Oppolzer ◽  
Hartmut Hauth ◽  
Paul Pfäffli ◽  
Roland Wenger
Keyword(s):  
Total Synthesis ◽  
Enol Ether ◽  
Enantioselective Total Synthesis ◽  
Silyl Enol Ether

scholarly journals Enantioselective Total Synthesis of (−)-Nardoaristolone B via a Gold(I)-Catalyzed Oxidative Cyclization

2015 ◽  
Vol 17 (3) ◽  
pp. 461-463 ◽  
Author(s):  
Anna Homs ◽  
Michael E. Muratore ◽  
Antonio M. Echavarren
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Enantioselective Total Synthesis

scholarly journals Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for Enantioselective Total Synthesis of Mavacuran Alkaloids

2019 ◽  
Vol 58 (29) ◽  
pp. 9861-9865 ◽  
Author(s):  
Maxime Jarret ◽  
Victor Turpin ◽  
Aurélien Tap ◽  
Jean‐François Gallard ◽  
Cyrille Kouklovsky ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Enantioselective Total Synthesis
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