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.

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>

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.

Chiron approach for the total synthesis of brevipolide M

Synlett ◽  
2022 ◽  
Author(s):  
Yang Liu ◽  
Ziyang Zhao ◽  
Chao Hu ◽  
Chuanfang Zhao ◽  
Jun Liu ◽  
...  
Keyword(s):  
Double Bond ◽  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Ring Closing Metathesis ◽  
One Pot ◽  
Double Bond Migration ◽  
Key Steps

An efficient stereoselective synthesis of brevipolide M was established in 13 linear steps and 17.8% overall yields base on chiron approach. The key steps of our synthesis involved tandem homologation / tetrahydrofuran cyclization and sequential ring-closing metathesis (RCM) / double-bond migration in one-pot processes.

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>

scholarly journals Stereoselective Synthesis of the I–L Fragment of the Pacific Ciguatoxins

Toxins ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 740
Author(s):  
J. Stephen Clark ◽  
Michael Popadynec
Keyword(s):  
Stereoselective Synthesis ◽  
Ring System ◽  
Membered Ring ◽  
Hydroxyl Groups ◽  
Oxidation Reactions ◽  
Metathesis Reaction ◽  
Ring Closing Metathesis ◽  
Selective Protection ◽  
Conjugate Reduction ◽  
The Pacific

The I–L ring system found in all the Pacific ciguatoxins has been prepared from a tricyclic precursor in a highly stereoselective manner. Subtle differences in the reactivity of the enones present in the seven- and eight-membered rings of the tricyclic ether starting material have been exploited to allow selective protection of the enone in the eight-membered ring. Subsequent distereoselective allylation of the seven-membered ring has been accomplished by a palladium-mediated Tsuji-Trost reaction. The K-ring methyl and hydroxyl groups have been installed in a highly stereoselective manner by sequential conjugate reduction and enolate oxidation reactions. Ring L has been constructed by a use of a novel relay ring-closing metathesis reaction to complete the tetracyclic framework, which possesses the functionality necessary for elaboration of rings I and L and the introduction of ring M.

A Chemoenzymatic Total Synthesis of the Undecenolide ( - )-Cladospolide C

2005 ◽  
Vol 58 (7) ◽  
pp. 511 ◽  
Author(s):  
Martin G. Banwell ◽  
David T. J. Loong ◽  
Anthony C. Willis
Keyword(s):  
Total Synthesis ◽  
Single Crystal ◽  
Natural Product ◽  
Absolute Configuration ◽  
Starting Material ◽  
Unsaturated Ester ◽  
Ring Closing Metathesis ◽  
X Ray ◽  
Key Steps ◽  
First Time

The (−)-enantiomer, ent-3, of the natural product (+)-cladospolide C (3) has been prepared for the first time using the monochiral cis-1,2-dihydrocatechol 5 as starting material. Key steps include coupling of the derived acid 6 with the enzymatically generated (S)-(+)-4-penten-2-ol (7) and ring-closing metathesis (RCM) of the resultant doubly unsaturated ester 8 to give lactone 9. The structure of this last compound has been confirmed by single-crystal X-ray analysis. This work has established that the absolute configuration of (+)-cladospolide C has been correctly assigned and is as illustrated in structure 3.

Total synthesis of cannabisin F

2014 ◽  
Vol 68 (3) ◽  
Author(s):  
Ya-Mu Xia ◽  
Jun Xia ◽  
Chen Chai
Keyword(s):  
Total Synthesis ◽  
Wittig Reaction ◽  
Aldol Reaction ◽  
Synthetic Strategy ◽  
First Time

AbstractA practical eight-step synthesis of lignanamide cannabisin F starting from vanillin is reported for the first time. This synthetic strategy applies the aldol reaction followed by the Wittig reaction to afford the key 8-O-4′-neolignan intermediate diacid. The diacid was condensed with N,O-protected tyramine giving, after deprotection, cannabisin F.

Sign in / Sign up

Export Citation Format

Share Document