The Identification and Synthesis of Further Lichen β-Orcinol para-Depsides

1989 ◽  
Vol 42 (7) ◽  
pp. 1191 ◽  
Author(s):  
JA Elix ◽  
DO Chester ◽  
KL Gaul ◽  
JL Parker ◽  
JH Wardlaw
Keyword(s):  
Total Synthesis ◽  
First Time

The new lichen depsides, methyl 5-chloronorobtusatate (4) and 4-O-demethyldiffractaic acid (5), have been detected in an Erioderma sp. And Xanthoparmelia duplicata Hale respectively, and the structures confirmed by total synthesis. In addition, the lichen depsides, 2'-O- methylatranorin (1), 2-O-methylsquamatic acid (2) and elatinic acid (3), have been prepared by unambiguous synthesis 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 Syntheses of Marchantins C, O and P as Promising Highly Bioactive Compounds

2011 ◽  
Vol 6 (3) ◽  
pp. 1934578X1100600
Author(s):  
Andreas Speicher ◽  
Judith Holz ◽  
Alexandra Hoffmann
Keyword(s):  
Total Synthesis ◽  
Bioactive Compounds ◽  
Natural Compounds ◽  
Marchantia Polymorpha ◽  
Antitumor Activities ◽  
Microtubule Inhibitor ◽  
First Time

Recently, remarkable microtubule inhibitor and antitumor activities of the bis(bibenzyl) marchantin C – isolated from liverworts like Marchantia polymorpha since 1983 – were found. In this paper we describe the efficient total synthesis of this subtype of bis(bibenzylic) compounds with two biarylether connections. Two selectively methylated derivatives known as natural compounds marchantin O and P were synthesized for the first time by modification of the arene subunits and can now be considered as promising highly bioactive compounds.

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.

scholarly journals Assessment of the Optimum Linker Tethering Site of Alternariol Haptens for Antibody Generation and Immunoassay Development

Toxins ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 883
Author(s):  
Luis G. Addante-Moya ◽  
Antonio Abad-Somovilla ◽  
Antonio Abad-Fuentes ◽  
Consuelo Agulló ◽  
Josep V. Mercader
Keyword(s):  
Total Synthesis ◽  
Monomethyl Ether ◽  
Alternariol Monomethyl Ether ◽  
Binding Properties ◽  
High Affinity ◽  
Structure Activity ◽  
Highly Sensitive ◽  
Alternaria Mycotoxins ◽  
Mycotoxin Analysis ◽  
First Time

Immunochemical methods for mycotoxin analysis require antigens with well-defined structures and antibodies with outstanding binding properties. Immunoreagents for the mycotoxins alternariol and/or alternariol monomethyl ether have typically been obtained with chemically uncharacterized haptens, and antigen conjugates have most likely been prepared with mixtures of functionalized molecules. For the first time, total synthesis was performed, in the present study, to obtain two haptens with opposite linker attachment locations. The functionalized synthetic haptens were purified and deeply characterized by different spectrometric methods, allowing the preparation of bioconjugates with unequivocal structures. Direct and indirect competitive enzyme-linked immunosorbent assays, using homologous and heterologous conjugates, were employed to extensively evaluate the generated immunoreagents. Antibodies with high affinity were raised from conjugates of both haptens, and a structure-activity relationship between the synthetic haptens and the specificity of the generated antibodies could be established. These results pave the way for the development of novel highly sensitive immunoassays selective of one or two of these Alternaria mycotoxins.

scholarly journals Neurymenolide A, a Novel Mitotic Spindle Poison from the New Caledonian Rhodophyta Phacelocarpus neurymenioides

Marine Drugs ◽  
2019 ◽  
Vol 17 (2) ◽  
pp. 93 ◽  
Author(s):  
Sofia-Eléna Motuhi ◽  
Omid Feizbakhsh ◽  
Béatrice Foll-Josselin ◽  
Blandine Baratte ◽  
Claire Delehouzé ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Cell Lines ◽  
Mitotic Spindle ◽  
Hematological Malignancies ◽  
Mitotic Catastrophe ◽  
Antibiotic Resistant ◽  
Resistant Strains ◽  
Stereogenic Center ◽  
First Time

The marine α-pyrone macrolide neurymenolide A was previously isolated from the Fijian red macroalga, Neurymenia fraxinifolia, and characterized as an antibacterial agent against antibiotic-resistant strains that also exhibited moderate cytotoxicity in vitro against cancer cell lines. This compound was also shown to exhibit allelopathic effects on Scleractinian corals. However, to date no mechanism of action has been described in the literature. The present study showed, for the first time, the isolation of neurymenolide A from the New Caledonian Rhodophyta, Phacelocarpus neurymenioides. We confirmed the compound’s moderate cytotoxicity in vitro against several human cell lines, including solid and hematological malignancies. Furthermore, we combined fluorescence microscopy and flow cytometry to demonstrate that treatment of U-2 OS osteosarcoma human cells with neurymenolide A could block cell division in prometaphase by inhibiting the correct formation of the mitotic spindle, which induced a mitotic catastrophe that led to necrosis and apoptosis. Absolute configuration of the stereogenic center C-17 of neurymenolide A was deduced by comparison of the experimental and theoretical circular dichroism spectra. Since the total synthesis of this compound has already been described, our findings open new avenues in cancer treatment for this class of marine molecules, including a new source for the natural product.

Stereoselective Total Synthesis of Arundinolides A and B

Synthesis ◽  
2020 ◽  
Vol 52 (10) ◽  
pp. 1576-1584
Author(s):  
Jun Liu ◽  
Zhi-Bing Dong ◽  
Caizhu Chang ◽  
Jialin Geng ◽  
Yinxin Liu ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Ethyl Lactate ◽  
Metathesis Reaction ◽  
Cross Metathesis ◽  
Key Features ◽  
First Time ◽  
Enantioselective Syntheses

The efficient and enantioselective syntheses of arundinolides A and B have been accomplished for the first time from chiral pool methyl-2,3-O-isopropylidene-β-d-ribofuranoside and d-ethyl lactate. The key features of the total synthesis are intramolecular crotonyl migration and NaBH4-CuCl catalyzed regioselective reduction and cross-metathesis reaction.

First Total Synthesis of Pamamycin-621D

2018 ◽  
Vol 15 (1) ◽  
pp. 105-109 ◽  
Author(s):  
Hassan Norouzi-Arasi ◽  
Xavier J. Salom-Roig ◽  
Steve Lanners ◽  
Gilles Hanquet
Keyword(s):  
Total Synthesis ◽  
Optical Rotation ◽  
Large Family ◽  
Synthetic Approach ◽  
General Strategy ◽  
Structural Assignment ◽  
12 Steps ◽  
Aldol Addition ◽  
Additional Support ◽  
First Time

Aim and Objective: The objective of our work was to synthesize and fully characterize Pamamycin- 621D, one of the less abundant members of a large family of macrodiolides with antimycobacterial properties, which had never been synthesized before. Furthermore, we also wished to improve our general strategy by using a new unsaturated precursor. Materials and Method: A new unsaturated ethylketone precursor was prepared using alkene cross metathesis, and a convergent and flexible strategy based on a key diastereoselective aldol addition was implemented to afford pamamycin-621D in 12 steps from that precursor. Results: Pamamycin-621D has been obtained and fully characterized for the first time. The structure of pamamycin-621D was confirmed by HRMS and comparison of 1H-NMR spectra with the natural pamamycin- 621D. Both optical rotation and 13C-NMR had not been published previously due to lack of material, and the latter are reported here for the first time. Given the scarce characterization available previously, our synthesis also gives additional support to the initial structural assignment of pamamycin-621D. A significant improvement of the key aldol addition via the use of a new unsaturated precursor is also reported. Conclusion: The work described above constitutes the first total synthesis of pamamycin-621D and has enabled us to fully characterize this scarcely available natural product. More importantly, this work highlights the fact that our synthetic approach provides ready access to various members of the pamamycin family, allowing possible studies on structure-activity relationships and mode of action of even the least abundant of these natural products. The synthesis of other pamamycin congeners and biological investigations will be published in due course.

Asymmetric total synthesis of cephanolide B

2021 ◽  
Author(s):  
Hongyuan Zhang ◽  
Haibing He ◽  
Shuanhu Gao
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Asymmetric Total Synthesis ◽  
First Time

The asymmetric synthesis of cephanolide B, a complex C18 Cephalotaxus dinorditerpenoid, is presented for the first time.

Total synthesis of nafuredin B

2020 ◽  
Vol 18 (12) ◽  
pp. 2346-2359
Author(s):  
Gour Hari Mandal ◽  
Dhiman Saha ◽  
Rajib Kumar Goswami
Keyword(s):  
Total Synthesis ◽  
Asymmetric Total Synthesis ◽  
Convergent Approach ◽  
First Time

Asymmetric total synthesis of nafuredin B has been achieved for the first time following a convergent approach.

scholarly journals First total synthesis of kipukasin A

2017 ◽  
Vol 13 ◽  
pp. 855-862 ◽  
Author(s):  
Chuang Li ◽  
Haixin Ding ◽  
Zhizhong Ruan ◽  
Yirong Zhou ◽  
Qiang Xiao
Keyword(s):  
Total Synthesis ◽  
Starting Material ◽  
Practical Approach ◽  
High Yield ◽  
Protecting Group ◽  
First Time

In this paper, a practical approach for the total synthesis of kipukasin A is presented with 22% overall yield by using tetra-O-acetyl-β-D-ribose as starting material. An improved iodine-promoted acetonide-forming reaction was developed to access 1,2-O-isopropylidene-α-D-ribofuranose. For the first time, ortho-alkynylbenzoate was used as protecting group for the 5-hydoxy group. After subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity.

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