ChemInform Abstract: A NEW ENANTIOSELECTIVE TOTAL SYNTHESIS OF NATURAL VINCAMINE VIA AN INTRAMOLECULAR MANNICH REACTION OF AN SILYL ENOL ETHER

A synthesis is described that leads from cyclopentadiene through 5-norbornen-2-one to the monosubstituted cyclopentenone 5; a vinyl substituent is attached by the reaction of a cuprate, and the enolate intermediate is trapped as the silyl enol ether 4, which is converted to 19, a product with the 10-carbon framework and stereochemistry of the secoxyloganin aglucone, and with all functional groups differentially protected and in the correct oxidation state. Explorations of the cuprate reaction required to convert the cyclopentenone 5 to the siloxycyclopentene 4 and of the reactions required for the oxidative cleavage of 4 reveal problems with these reactions when they are applied to compounds that are cyclopentane derivatives. The resolution of these problems leads to reaction sequences that proceed with high yields and excellent diastereoselectivity. Keywords: synthesis, secoxyloganin, vinyl cuprate, oxidative cleavage.

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Total synthesis of (−)-agelastatin A: an SH2′ radical azidation strategy

Chemical Communications ◽

10.1039/c8cc05697h ◽

2018 ◽

Vol 54 (71) ◽

pp. 9893-9896 ◽

Cited By ~ 4

Author(s):

Izuru Tsuchimochi ◽

Yuta Kitamura ◽

Hiroshi Aoyama ◽

Shuji Akai ◽

Keiyo Nakai ◽

...

Keyword(s):

Total Synthesis ◽

Synthetic Approach ◽

Enol Ether ◽

Agelastatin A ◽

Silyl Enol Ether ◽

Strategic Implementation ◽

Allylic Bromide

A new synthetic approach to (−)-agelastatin A has been established through the strategic implementation of brominative olefin transposition of a silyl enol ether and subsequent SH2′ radical azidation of the resultant allylic bromide.

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

10.26434/chemrxiv.12479312.v1 ◽

2020 ◽

Author(s):

Yingchao Dou ◽

Cyrille Kouklovsky ◽

Guillaume Vincent

Keyword(s):

Total Synthesis ◽

Second Generation ◽

Oxidative Cyclization ◽

Enol Ether ◽

Enantioselective Total Synthesis ◽

Terminal Alkene

We report our second generation synthesis of (–)-cymoside as well as the formation of a new hexacyclic-fused furo[3,2-b]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-(S)-strictosidine stereochemistry delivered efficiently the scaffold of cymoside via intramolecular coupling with the C16-C17 enol ether, while the 3-(R)-vincoside stereochemistry directed towards the reaction with the C18-C19 terminal alkene and the formation of the unexpected caged compound.

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Total Synthesis of (±)-Cephalosol via Silyl Enol Ether Acylation

Synthesis ◽

10.1055/s-0029-1218647 ◽

2010 ◽

Vol 2010 (06) ◽

pp. 917-922 ◽

Cited By ~ 2

Author(s):

Ulrich Koert ◽

Alexander Arlt

Keyword(s):

Total Synthesis ◽

Enol Ether ◽

Silyl Enol Ether

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Studies on the asymmetric synthesis of pandamarilactonines: an unexpected syn-selective vinylogous Mannich reaction of N-tert-butanesulfinimines

Organic Chemistry Frontiers ◽

10.1039/c5qo00098j ◽

2015 ◽

Vol 2 (6) ◽

pp. 697-704 ◽

Cited By ~ 9

Author(s):

Jian-Liang Ye ◽

Yu-Feng Zhang ◽

Yang Liu ◽

Jin-Yuan Zhang ◽

Yuan-Ping Ruan ◽

...

Keyword(s):

Total Synthesis ◽

Asymmetric Synthesis ◽

Mannich Reaction ◽

Enantioselective Total Synthesis

Through an unanticipatedsyn-selective VMR, a highly enantioselective total synthesis of (−)-pandamarilactonine-A has been achieved.

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

10.26434/chemrxiv.12479312 ◽

2020 ◽

Author(s):

Yingchao Dou ◽

Cyrille Kouklovsky ◽

Guillaume Vincent

Keyword(s):

Total Synthesis ◽

Second Generation ◽

Oxidative Cyclization ◽

Enol Ether ◽

Enantioselective Total Synthesis ◽

Terminal Alkene

We report our second generation synthesis of (–)-cymoside as well as the formation of a new hexacyclic-fused furo[3,2-b]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-(S)-strictosidine stereochemistry delivered efficiently the scaffold of cymoside via intramolecular coupling with the C16-C17 enol ether, while the 3-(R)-vincoside stereochemistry directed towards the reaction with the C18-C19 terminal alkene and the formation of the unexpected caged compound.

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