Natural products with taxol-like anti-tumor activity: Synthetic approaches to eleutherobin and dictyostatin

2007 ◽  
Vol 79 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Cesare Gennari ◽  
Damiano Castoldi ◽  
Ofer Sharon
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Cytotoxic Activity ◽  
Natural Product ◽  
Mode Of Action ◽  
Dynamic Instability ◽  
Ring System ◽  
Ring Closing Metathesis ◽  
Synthetic Approaches ◽  
Anti Tumor Activity

Eleutherobin and dictyostatin are antimitotic compounds which exert their cytotoxic activity by a taxol-like mode of action, i.e., hypernucleating tubulin assembly and interfering with the dynamic instability of the cytoskeleton during mitosis. A formal total synthesis of eleutherobin was accomplished by accessing a key intermediate reported by Danishefsky and coworkers in their 1998 synthesis of the natural product. The key step of our strategy, used for obtaining the [8.4.0] fused bicyclic ring system, is a ring-closing metathesis (RCM) reaction of a densely functionalized diene under forcing conditions, using Grubbs' second-generation catalyst. Synthetic approaches to dictyostatin are also described, and in particular the preparation of the C15-C23 fragment of the macrolide, containing 5 of its 11 stereocenters.

scholarly journals Synthesis of Highly Functionalised Furo[3,4-b]pyrans: Towards the Fungal Metabolite (−)-TAN-2483B

2021 ◽  
Author(s):  
◽  
R.M. Kalpani K. Somarathne
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Cyclopropane Ring ◽  
Ring Expansion ◽  
Ethyl Esters ◽  
Pyran Ring ◽  
Synthetic Strategy ◽  
Alternative Approach ◽  
Synthetic Approaches

<p>Carbohydrate-derived cyclopropanes combine both the stereochemical wealth of carbohydrates and the reactivity of cyclopropanes. A diverse variety of reaction modes for these cyclopropyl carbohydrates can be harnessed for the synthesis of natural products and other targets.  The natural products (−)-TAN-2483A and (−)-TAN-2483B are fungal secondary metabolites displaying a variety of bioactivities such as inhibition of c-src kinase action and parathyroid hormone-induced bone resorption. This thesis described several synthetic approaches to the natural product (−)-TAN-2483B and analogues of (−)-TAN-2483B employing cyclopropane ring expansion.  The synthetic route to (−)-TAN-2483B began with the readily available substrate D-mannose. The pyran ring unsaturation of the natural product was established by a cyclopropanation-ring expansion sequence. A synthetic strategy via dichlorocyclopropane-based intermediates is described in chapter 2. This being unsuccessful, an alternative approach via 2-fomyl-glycal was developed in chapter 3. The chapter 2 and 3 provided a solid background for the achievement of the analogues synthesis illustrated in chapter 4 via dibromocyclopropane. Lewis acid-mediated alkynylation followed by Pdcatalysed carbonylative lactonisation was successfully utilised in the revelation of the furo[3,4-b]pyran ring skeleton. This route afforded analogues of TAN-2483B; the Z-and E-unsaturated ethyl esters 140 and 141 and hydroxy(−)-TAN-2483B 145. The total synthesis of (−)-TAN-2483B was not achieved due to unforeseen obstacles encountered in the deoxygenation of the side arm of 335 (Chapter 4) into the E-propenyl side arm of (−)-TAN-2483B.</p>

scholarly journals Synthesis of Highly Functionalised Furo[3,4-b]pyrans: Towards the Fungal Metabolite (−)-TAN-2483B

2021 ◽  
Author(s):  
◽  
R.M. Kalpani K. Somarathne
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Cyclopropane Ring ◽  
Ring Expansion ◽  
Ethyl Esters ◽  
Pyran Ring ◽  
Synthetic Strategy ◽  
Alternative Approach ◽  
Synthetic Approaches

<p>Carbohydrate-derived cyclopropanes combine both the stereochemical wealth of carbohydrates and the reactivity of cyclopropanes. A diverse variety of reaction modes for these cyclopropyl carbohydrates can be harnessed for the synthesis of natural products and other targets.  The natural products (−)-TAN-2483A and (−)-TAN-2483B are fungal secondary metabolites displaying a variety of bioactivities such as inhibition of c-src kinase action and parathyroid hormone-induced bone resorption. This thesis described several synthetic approaches to the natural product (−)-TAN-2483B and analogues of (−)-TAN-2483B employing cyclopropane ring expansion.  The synthetic route to (−)-TAN-2483B began with the readily available substrate D-mannose. The pyran ring unsaturation of the natural product was established by a cyclopropanation-ring expansion sequence. A synthetic strategy via dichlorocyclopropane-based intermediates is described in chapter 2. This being unsuccessful, an alternative approach via 2-fomyl-glycal was developed in chapter 3. The chapter 2 and 3 provided a solid background for the achievement of the analogues synthesis illustrated in chapter 4 via dibromocyclopropane. Lewis acid-mediated alkynylation followed by Pdcatalysed carbonylative lactonisation was successfully utilised in the revelation of the furo[3,4-b]pyran ring skeleton. This route afforded analogues of TAN-2483B; the Z-and E-unsaturated ethyl esters 140 and 141 and hydroxy(−)-TAN-2483B 145. The total synthesis of (−)-TAN-2483B was not achieved due to unforeseen obstacles encountered in the deoxygenation of the side arm of 335 (Chapter 4) into the E-propenyl side arm of (−)-TAN-2483B.</p>

scholarly journals Applications of the Horner-Wadsworth-Emmons olefination in modern natural product synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Dávid Roman ◽  
Maria Sauer ◽  
Christine Beemelmanns
Keyword(s):  
Natural Products ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Reaction Conditions ◽  
Comprehensive Review ◽  
Modern Natural ◽  
Key Steps ◽  
Synthetic Approaches

Here, we have summarized more than 30 representative natural product syntheses published in 2015 to 2020 that employ one or more Horner-Wadsworth-Emmons (HWE) reactions. We comprehensively describe the applied phosphonate reagents, HWE reaction conditions and key steps of the total synthetic approaches. Our comprehensive review will support future synthetic approaches and serve as guideline to find the best HWE conditions for the most complicated natural products known

scholarly journals Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

2014 ◽  
Vol 10 ◽  
pp. 1228-1232 ◽  
Author(s):  
Jens Schmidt ◽  
Zeinab Khalil ◽  
Robert J Capon ◽  
Christian B W Stark
Keyword(s):  
Antibacterial Activity ◽  
Natural Products ◽  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Natural Product ◽  
Joint Effort ◽  
Natural Product Biosynthesis ◽  
New Members ◽  
Degree Of Oxidation ◽  
Rare Class

The heronapyrroles A–C have first been isolated from a marine-derived Streptomyces sp. (CMB-0423) in 2010. Structurally, these natural products feature an unusual nitropyrrole system to which a partially oxidized farnesyl chain is attached. The varying degree of oxidation of the sesquiterpenyl subunit in heronapyrroles A–C provoked the hypothesis that there might exist other hitherto unidentified metabolites. On biosynthetic grounds a mono-tetrahydrofuran-diol named heronapyrrole D appeared a possible candidate. We here describe a short asymmetric synthesis of heronapyrrole D, its detection in cultivations of CMB-0423 and finally the evaluation of its antibacterial activity. We thus demonstrate that biosynthetic considerations and the joint effort of synthetic and natural product chemists can result in the identification of new members of a rare class of natural products.

scholarly journals Total Synthesis of the Reported Structure of Cahuitamycin A

2020 ◽  
Author(s):  
Justin Shapiro ◽  
Savannah Post ◽  
William Wuest
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Twelve Step ◽  
Target Compound ◽  
New Family ◽  
Iron Trafficking ◽  
Linear Sequence ◽  
Alternative Structure ◽  
Synthetic Target

In a 2016 screen of natural product extracts a new family of natural products, the cahuitamycins, was discovered and found to inhibit the formation of biofilms in the human pathogen <i>Acinetobacter baumannii</i>. The molecules contain an unusual piperazate residue that raises structure/function and biosynthesis questions and resemble iron-trafficking virulence factors from <i>A. baumannii</i>, suggesting a connection between metal homeostasis and biofilm-mediated pathogenicity. Here we disclose the first total synthesis of the reported structure of cahuitamycin A in a twelve-step longest linear sequence and 18% overall yield. Comparison of spectral data of the authentic natural product and synthetic target compound demonstrate that the reported structure is distinct from the isolated metabolite. Herein, we propose an alternative structure to reconcile our findings with the isolation report, setting the stage for future synthetic and biochemical investigations of an important class of natural products.

scholarly journals Total Syntheses of Pladienolide-Derived Spliceosome Modulators

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5938
Author(s):  
Jaehoon Sim ◽  
Eunbin Jang ◽  
Hyun Jin Kim ◽  
Hongjun Jeon
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Structural Features ◽  
Synthetic Approach ◽  
Synthetic Analog ◽  
Phase I Clinical Trials ◽  
Total Syntheses ◽  
Naturally Occurring ◽  
Anti Cancer ◽  
Synthetic Approaches

Pladienolides, an emerging class of naturally occurring spliceosome modulators, exhibit interesting structural features, such as highly substituted 12-membered macrocycles and epoxide-containing diene side chains. The potential of pladienolides as anti-cancer agents is confirmed by H3B-8800, a synthetic analog of this natural product class, which is currently under Phase I clinical trials. Since its isolation in 2004 and the first total synthesis in 2007, a dozen total syntheses and synthetic approaches toward the pladienolide class have been reported to date. This review focuses on the eight completed total syntheses of naturally occurring pladienolides or their synthetic analogs, in addition to a synthetic approach to the main framework of the natural product.

scholarly journals Synthetic study of ravidomycin, a hybrid natural product

2000 ◽  
Vol 72 (9) ◽  
pp. 1783-1786 ◽  
Author(s):  
Keisuke Suzuki
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Amino Sugar ◽  
Antitumor Antibiotics ◽  
Ready Availability ◽  
Silyl Acetals ◽  
Gilvocarcin V ◽  
Absolute Stereochemistry

Strategies and tactics associated with the total synthesis of hybrid natural products are discussed. The target is ravidomycin (2), one of the gilvocarcin-class antitumor antibiotics with an aryl C-glycoside structure. The first total synthesis of 2, which was achieved along similar lines of that of gilvocarcin V (1), served for the determination of the relative as well as the absolute stereochemistry of 2. Also revealed was a limitation of the synthetic scheme so long as the amino sugar congener was concerned. A preliminary result is discussed on the [2+2+2] approach that relies on the ready availability of various benzocyclobutene derivatives via regioselective [2+2] cycloaddition of α-alkoxybenzynes and ketene silyl acetals.

scholarly journals Harnessing the biocatalytic potential of iron- and α-ketoglutarate-dependent dioxygenases in natural product total synthesis

2020 ◽  
Vol 37 (8) ◽  
pp. 1065-1079 ◽  
Author(s):  
Christian R. Zwick ◽  
Hans Renata
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Oxidative Transformations

This review highlights recent chemoenzymatic syntheses of natural products that feature strategic applications of oxidative transformations with Fe/αKG enzymes.

Recent advances in the synthesis of oxaspirolactones and their application in the total synthesis of related natural products

2019 ◽  
Vol 17 (31) ◽  
pp. 7270-7292 ◽  
Author(s):  
Sagar S. Thorat ◽  
Ravindar Kontham
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Medicinal Chemistry ◽  
Natural Product Chemistry ◽  
Structural Motifs ◽  
Recent Advances ◽  
Synthetic Molecules ◽  
Product Chemistry

Oxaspirolactones are ubiquitous structural motifs found in natural products and synthetic molecules with a diverse biochemical and physicochemical profile, and represent a valuable target in natural product chemistry and medicinal chemistry.

scholarly journals Synthetic Approaches to Tetracyclic Pyrrole Imidazole Marine Alkaloids

2013 ◽  
Vol 8 (7) ◽  
pp. 1934578X1300800 ◽  
Author(s):  
Takuya Imaoka ◽  
Makoto Iwata ◽  
Takafumi Akimoto ◽  
Kazuo Nagasawa
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Anticancer Activity ◽  
Biological Activities ◽  
Structural Complexity ◽  
Marine Alkaloids ◽  
Ring Systems ◽  
Agonistic Activity ◽  
Synthetic Approaches

Oroidin derived pyrrole imidazole marine alkaloids (PIAs) are attractive targets for synthetic organic chemists because of their structural complexity and diversity as well as their interesting biological activities. A number of efforts have been carried out to develop strategies for the synthesis of these natural products. Members of PIAs ( eg., 2-7) which contain tetracyclic ring systems possessing characteristic cyclic guanidine or urea moieties show significant biological activities including anticancer activity and agonistic activity against the adrenoceptor. In this review investigations of the total synthesis of the representative tetracyclic PIAs dibromophakellin (2) and dibromophakellstatin (3) are described.

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