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.

scholarly journals Palladium-Catalyzed Coupling Reactions on Functionalized 2-Trifluoromethyl-4-chromenone Scaffolds: Synthesis of Highly Functionalized Trifluoromethyl Heterocycles

Synthesis ◽  
2018 ◽  
Vol 51 (06) ◽  
pp. 1342-1352 ◽  
Author(s):  
Javier Izquierdo ◽  
Atul Jain ◽  
Sarki Abdulkadir ◽  
Gary Schiltz
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Biological Activities ◽  
Structural Complexity ◽  
Biologically Active ◽  
Coupling Reactions ◽  
Trifluoromethyl Group ◽  
Palladium Catalyzed ◽  
Active Natural

The chromenone core is an ubiquitous group in biologically active natural products and has been extensively used in organic synthesis. Fluorine-derived compounds, including those with a trifluoromethyl group (CF3), have shown enhanced biological activities in numerous pharmaceuticals compared with their non-fluorinated analogues. 2-Trifluoromethylchromenones can be readily functionalized at the 8- and 7-positions, providing chromenones cores of high structural complexity, which are excellent precursors for numerous trifluoromethyl heterocycles.

scholarly journals Divergent synthesis of complex diterpenes through a hybrid oxidative approach

Science ◽  
2020 ◽  
Vol 369 (6505) ◽  
pp. 799-806 ◽  
Author(s):  
Xiao Zhang ◽  
Emma King-Smith ◽  
Liao-Bin Dong ◽  
Li-Cheng Yang ◽  
Jeffrey D. Rudolf ◽  
...  
Keyword(s):  
Natural Products ◽  
De Novo ◽  
Biological Activities ◽  
Structural Complexity ◽  
Enzymatic Oxidation ◽  
Chemical Tools ◽  
Skeletal Rearrangements ◽  
Skeletal Diversity

Polycyclic diterpenes exhibit many important biological activities, but de novo synthetic access to these molecules is highly challenging because of their structural complexity. Semisynthetic access has also been limited by the lack of chemical tools for scaffold modifications. We report a chemoenzymatic platform to access highly oxidized diterpenes by a hybrid oxidative approach that strategically combines chemical and enzymatic oxidation methods. This approach allows for selective oxidations of previously inaccessible sites on the parent carbocycles and enables abiotic skeletal rearrangements to additional underlying architectures. We synthesized a total of nine complex natural products with rich oxygenation patterns and skeletal diversity in 10 steps or less from ent-steviol.

Synthetic approaches to [5,6]-benzannulated spiroketal natural products

2011 ◽  
Vol 84 (6) ◽  
pp. 1379-1390 ◽  
Author(s):  
Michael C. McLeod ◽  
Margaret A. Brimble ◽  
Dominea C. K. Rathwell ◽  
Zoe E. Wilson ◽  
Tsz-Ying Yuen
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Electronic Properties ◽  
Late Stage ◽  
Biologically Active ◽  
Formal Synthesis ◽  
Berkelic Acid ◽  
Synthetic Approaches

Studies toward the synthesis of three biologically active [5,6]-benzannulated spiroketal natural products are described. The first total synthesis of paecilospirone is reported, employing a late-stage, pH-neutral spiroketalization. A formal synthesis of γ-rubromycin is described, where the spiroketal moiety is formed by delicate manipulation of the electronic properties of the spirocyclization precursor. Finally, model work toward the total synthesis of berkelic acid is summarized, introducing a novel Horner–Wadsworth–Emmons/oxa-Michael (HWE/oxa-M) cascade to access the spiroketal precursor.

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 Making drugs out of sunlight and ‘thin air’: an emerging synergy of synthetic biology and natural product chemistry

2020 ◽  
Vol 42 (4) ◽  
pp. 34-39
Author(s):  
Michael J. Stephenson ◽  
Anne Osbourn
Keyword(s):  
Natural Products ◽  
Synthetic Biology ◽  
Natural Product ◽  
Large Scale ◽  
Production Systems ◽  
Biological Activities ◽  
Structural Complexity ◽  
Scale Production ◽  
Natural Product Chemistry ◽  
Product Chemistry

Nature has long served as a rich source of structurally diverse small organic molecules with medicinally relevant biological activities. Despite the historical success of these so-called natural products, the enthusiasm of big pharma to explore these compounds as leads in drug design has waxed and waned. A major contributor to this is their often inherent structural complexity. Such compounds are difficult (often impossible) to access synthetically, a hurdle that can stifle lead development and hinder sustainable large-scale production of promising leads for clinical evaluation. However, in recent years, an emerging synergy between synthetic biology and natural product chemistry offers the potential for a renaissance in our ability to access natural products for drug discovery and development. Advances in genome sequencing, bioinformatics and the maturing of heterologous expression platforms are increasing, enabling the study, and ultimately, the manipulation of plant biosynthetic pathways. The triterpenes are one of the most structurally diverse families of natural products and arguably one of the most underrepresented in the clinic. The plant kingdom is the richest source of triterpene diversity, with &gt;20,000 triterpenes reported so far. Transient expression of genes for candidate enzymes and pathways in amenable plant species is emerging as a powerful and rapid means of investigating and harnessing the plant enzymes involved in generating this diversity. Such platforms also have the potential to serve as production systems in their own right, with the possibility of upscaling these discoveries into commercially useful products using the same overall basic procedure. Ultimately, the carbon source for generation of high-value compounds in plants is photosynthesis. Therefore, we could, with the help of plants, be producing new medicines out of sunlight and ‘thin air’ in green factories in the not too distant future.

scholarly journals Gold-Catalyzed Synthetic Strategies towards Four-Carbon Ring Systems

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1178
Author(s):  
Guillermo Otárola ◽  
Juan J. Vaquero ◽  
Estíbaliz Merino ◽  
Manuel A. Fernández-Rodríguez
Keyword(s):  
Natural Products ◽  
Biological Activities ◽  
High Reactivity ◽  
Synthetic Methods ◽  
Efficient Manner ◽  
Ring Systems ◽  
Carbon Ring ◽  
Wide Range ◽  
Long Time ◽  
Complex Organic

Four carbon ring systems are frequently present in natural products with remarkable biological activities such as terpenoids, alkaloids, and steroids. The development of new strategies for the assembly of these structures in a rapid and efficient manner has attracted the interest of synthetic chemists for a long time. The current research is focused mainly on the development of synthetic methods that can be performed under mild reaction conditions with a high tolerance to functional groups. In recent years, gold complexes have turned into excellent candidates for this aim, owing to their high reactivity, and are thus capable of promoting a wide range of transformations under mild conditions. Their remarkable efficiency has been thoroughly demonstrated in the synthesis of complex organic molecules from simple starting materials. This review summarizes the main synthetic strategies described for gold-catalyzed four-carbon ring formation, as well as their application in the synthesis of natural products.

Dihydroresveratrol Type Dihydrostilbenoids: Chemical Diversity, Chemosystematics, and Bioactivity

2018 ◽  
Vol 25 (10) ◽  
pp. 1194-1240 ◽  
Author(s):  
Sara Vitalini ◽  
Serhat S. Cicek ◽  
Sebastian Granica ◽  
Christian Zidorn
Keyword(s):  
Natural Products ◽  
Anticancer Activity ◽  
Biological Activities ◽  
Wide Spectrum ◽  
Pathogenic Fungi ◽  
Chemical Diversity ◽  
Limited Information ◽  
Lead Compounds ◽  
Naturally Occurring

Background: Dihydrostilbenoids, a diverse class of natural products differing from stilbenoids by the missing double bond in the ethylene chain linking the aromatic moieties, have been reported from fungi, mosses, ferns, and flowering plants. Objective: Occurrence, structure, and bioactivity of naturally occurring dihydroresveratrol type dihydrostilbenoids are discussed in this review. Method: A Reaxys database search for dihydroresveratrol derivatives with possible substitutions on all atoms, but excluding non-natural products and compounds featuring additional rings involving the ethyl connecting chain, was performed. Results: Structures include simple dihydroresveratrol derivatives, compounds substituted with complex side chains composed of acyl moieties and sugars, and compounds containing polycyclic cores attached to dihydrostilbenoid units. Dihydrostilbenoids have a wide spectrum of bioactivities ranging from expectable antioxidant and anti-inflammatory activities to interesting neuroprotective and anticancer activity. The anticancer activity in particular is very pronounced for some plant-derived dihydrostilbenoids and makes them interesting lead compounds for drug development. Apart from some reports on dihydroresveratrol derivatives as phytoalexins against plant-pathogenic fungi, only very limited information is available on the ecological role of these compounds for the organisms producing them. Conclusion: Dihydrostilbenoids are a class of natural products possessing significant biological activities; their scattered but not ubiquitous occurrence throughout the kingdoms of plants and fungi is not easily explained. We are convinced that future studies will identify new sources of dihydrostilbenoids, and we hope that the present review will inspire such studies and will help in directing such efforts to suitable source organisms and towards promising bioactivities.

Total synthesis of bryostatin 3

Science ◽  
2020 ◽  
Vol 368 (6494) ◽  
pp. 1007-1011 ◽  
Author(s):  
Barry M. Trost ◽  
Youliang Wang ◽  
Andreas K. Buckl ◽  
Zhongxing Huang ◽  
Minh H. Nguyen ◽  
...  
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Marine Natural Products ◽  
Biological Activities ◽  
Step Count ◽  
Total Syntheses ◽  
Linear Sequence ◽  
Wide Range

Bryostatins are a family of 21 complex marine natural products with a wide range of potent biological activities. Among all the 21 bryostatins, bryostatin 3 is structurally the most complex. Whereas nine total syntheses of bryostatins have been achieved to date, bryostatin 3 has only been targeted once and required the highest number of steps to synthesize (43 steps in the longest linear sequence and 88 total steps). Here, we report a concise total synthesis of bryostatin 3 using 22 steps in the longest linear sequence and 31 total steps through a highly convergent synthetic plan by the use of highly atom-economical and chemoselective transformations in which alkynes played a major role in reducing step count.

scholarly journals Aminomethylation/hydrogenolysis as an alternative to direct methylation of metalated isoquinolines – a novel total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline

2018 ◽  
Vol 14 ◽  
pp. 130-134 ◽  
Author(s):  
Benedikt C Melzer ◽  
Jan G Felber ◽  
Franz Bracher
Keyword(s):  
Natural Products ◽  
Drug Development ◽  
Total Synthesis ◽  
Benzyl Ether ◽  
Methyl Group ◽  
Novel Method ◽  
Synthetic Approaches

Highly-substituted isoquinolines are important scaffolds in syntheses of natural products and in drug development and hence, effective synthetic approaches are required. Here we present a novel method for the introduction of a methyl group at C1 of isoquinolines. This is exemplified by a new total synthesis of the alkaloid 7-hydroxy-6-methoxy-1-methylisoquinoline. Direct metalation of 7-benzyloxy-6-methoxyisoquinoline with Knochel–Hauser base, followed by cuprate-mediated methylation gives the target alkaloid directly, but separation from the educt is cumbersome. Quenching the metalated intermediate with Eschenmoser’s reagent gives an easy to clean tertiary benzylamine, which, after quaternization with iodomethane, is easily converted into the desired 1-methylisoquinoline by hydrogenolysis of both the benzylamine and benzyl ether groups.

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