scholarly journals Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

2020 ◽  
Vol 16 ◽  
pp. 670-673
Author(s):  
Jan Geldsetzer ◽  
Markus Kalesse
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Cross Coupling ◽  
Vinyl Bromide ◽  
Type Coupling ◽  
Chiral Centers

The stereoselective synthesis of the (Z)-enamide fragment of chondrochloren (1) is described. A Buchwald-type coupling between amide 3 and (Z)-bromide 4 was used to generate the required fragment. The employed amide 3 comprising three chiral centers was obtained through a seven-step sequence starting from ᴅ-ribonic acid-1,4-lactone. The (Z)-vinyl bromide 4 is accessible in four steps from 4-hydroxybenzaldehyde. The pivotal cross coupling between both fragments was achieved after extensive experimentation with copper(I) iodide, K2CO3 and N,N′-dimethylethane-1,2-diamine.

Towards the Total Synthesis of Schisandrene: Stereoselective Synthesis of the Dibenzocyclooctadiene Lignan Core

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 908-911 ◽  
Author(s):  
K. Babu ◽  
Arramshetti Venkanna ◽  
Borra Poornima ◽  
Bandi Siva ◽  
B. Babu
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Asymmetric Reduction ◽  
Cross Coupling ◽  
Membered Ring ◽  
Stille Reaction ◽  
Reaction Sequence ◽  
Ring Closing Metathesis ◽  
Synthetic Strategy ◽  
First Time

A stereoselective synthesis of the dibenzocyclooctadiene ­lignan core of the natural product schisandrene is described. Starting from readily available gallic acid, the synthetic strategy involves Suzuki–Miyaura cross-coupling, Stille reaction, and ring-closing metathesis (RCM) in the reaction sequence. The required asymmetric center at C-7′ was established by an asymmetric reduction of a keto compound using the Corey–Bakshi–Shibata (CBS) catalyst. In our approach, the eight-membered ring was achieved by RCM for the first time.

Enantioselective Multi-Component Cyclopropane Synthesis Enabled by Cu-Catalyzed Cyclopropene Carbometallation with Organoboron Reagent

2018 ◽  
Author(s):  
Zhanyu Li ◽  
Mengru Zhang ◽  
Yu Zhang ◽  
Shuang Liu ◽  
Jinbo Zhao ◽  
...  
Keyword(s):  
Carbon Source ◽  
Stereoselective Synthesis ◽  
Organometallic Reagents ◽  
Preliminary Results ◽  
Quaternary Center ◽  
Chiral Centers ◽  
Substituted Cyclopropanes ◽  
Proof Of Principle

Deployment of organoboron in lieu of the strongly basic <br>organometallic reagents as carbon source in Cu-catalyzed <br>cyclopropene carbometallation opens unprecedented three-<br>component reactivity for stereoselective synthesis of poly-substituted cyclopropanes. A proof-of-principle demonstration of this novel carbometallation strategy is presented herein for a highly convergent access to poly-substituted aminocyclopropane framework via <br>carboamination. Preliminary results on asymmetric desymmetrization with commercial bisphosphine ligands attained high levels of enantioselection, offering a straightforward access to enantioenriched aminocyclopropanes bearing all-three chiral centers, including an all-carbon quaternary center. This strategy may underpin a host of novel synthetic protocols for poly-substituted cyclopropanes. <br>

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

Concise Total Synthesis of Curvulone B

Synlett ◽  
2020 ◽  
Author(s):  
Debendra K. Mohapatra ◽  
Shivalal Banoth ◽  
Utkal Mani Choudhury ◽  
Kanakaraju Marumudi ◽  
Ajit C. Kunwar
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Ring System ◽  
Bond Forming ◽  
Cross Metathesis ◽  
Bond Forming Reactions ◽  
Key Steps

AbstractA concise and convergent stereoselective synthesis of curvulone B is described. The synthesis utilized a tandem isomerization followed by C–O and C–C bond-forming reactions following Mukaiyama-type aldol conditions for the construction of the trans-2,6-disubstituted dihydropyran ring system as the key steps. Other important features of this synthesis are a cross-metathesis, epimerization, and Friedel–Crafts acylation.

Concise total synthesis of honokiol via Kumada cross coupling

2014 ◽  
Vol 55 (31) ◽  
pp. 4295-4297 ◽  
Author(s):  
Jada Srinivas ◽  
Parvinder Pal Singh ◽  
Yogesh Kumar Varma ◽  
Irfan Hyder ◽  
Halmuthur M. Sampath Kumar
Keyword(s):  
Total Synthesis ◽  
Cross Coupling

Stereoselective synthesis of O-tosyl azabicyclic derivatives via aza Prins reaction of endocyclic N-acyliminium ions: application to the total synthesis of (±)-epi-indolizidine 167B and 209D

2014 ◽  
Vol 12 (36) ◽  
pp. 7026-7035 ◽  
Author(s):  
Anil K. Saikia ◽  
Kiran Indukuri ◽  
Jagadish Das
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Cyclization Reaction ◽  
Diastereoselective Synthesis ◽  
Prins Reaction ◽  
Prins Cyclization ◽  
Acyliminium Ions

A diastereoselective synthesis of 4-O-tosyl piperidine containing azabicyclic derivatives has been established via Prins cyclization reaction. This protocol has been applied for the total synthesis of (±)-epi-indolizidine 167B and 209D.

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