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Journal articles on the topic 'Natural Products - Stereochemistry'

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

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1

Pattan, S. R., S. S. Kadam, S. A. Nirmal, D. K. Thakur, J. S. Pattan, and G. M. Nazeruddin. "SCOPE FOR THE DEVELOPMENT OF SPECTROSCOPIC METHODS IN DETERMINATION OF STEREOCHEMISTRY OF NATURAL PRODUCTS." INDIAN DRUGS 49, no. 02 (2012): 5–11. http://dx.doi.org/10.53879/id.49.02.p0005.

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India is a rich country in terms of biodiversity & natural products, but very little work is carried out on stereochemical & spectroscopic studies of natural products. Isomers of natural products are found to be active, but the detection of stereochemical/spectral data is not effectively achieved. There is tremendous scope for spectroscopic methods in the determination of stereochemistry of some novel natural products particularly on J based approach (coupling constant values) which reveals about configuration, conformation and reactivity. Coupling varies with the angle between bonds,

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2

Matulja, Dario, Karlo Wittine, Nela Malatesti, et al. "Marine Natural Products with High Anticancer Activities." Current Medicinal Chemistry 27, no. 8 (2020): 1243–307. http://dx.doi.org/10.2174/0929867327666200113154115.

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This review covers recent literature from 2012-2019 concerning 170 marine natural products and their semisynthetic analogues with strong anticancer biological activities. Reports that shed light on cellular and molecular mechanisms and biological functions of these compounds, thus advancing the understanding in cancer biology are also included. Biosynthetic studies and total syntheses, which have provided access to derivatives and have contributed to the proper structure or stereochemistry elucidation or revision are mentioned. The natural compounds isolated from marine organisms are divided i

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3

Cadelis, Melissa M., Brent R. Copp, and Siouxsie Wiles. "A Review of Fungal Protoilludane Sesquiterpenoid Natural Products." Antibiotics 9, no. 12 (2020): 928. http://dx.doi.org/10.3390/antibiotics9120928.

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Natural products have been a great source for drug leads, due to a vast majority possessing unique chemical structures. Such an example is the protoilludane class of natural products which contain an annulated 5/6/4-ring system and are almost exclusively produced by fungi. They have been reported to possess a diverse range of bioactivities, including antimicrobial, antifungal and cytotoxic properties. In this review, we discuss the isolation, structure elucidation and any reported bioactivities of this compound class, including establishment of stereochemistry and any total syntheses of these

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4

Brimble, Margaret, and Daniel Furkert. "Chemistry of Bis-Spiroacetal Systems: Natural Products, Synthesis and Stereochemistry." Current Organic Chemistry 7, no. 14 (2003): 1461–84. http://dx.doi.org/10.2174/1385272033486404.

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5

Hanessian, S., Roberto Margarita, Adrian Hall, Shawn Johnstone, M. Tremblay, and L. Parlanti. "New and old challenges in total synthesis. From concept to practice." Pure and Applied Chemistry 75, no. 2-3 (2003): 209–21. http://dx.doi.org/10.1351/pac200375020209.

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The total synthesis of dysinosin A, a novel member of the aeruginosin group of marine natural products is discussed. The stereocontrolled synthesis also confirms the proposed structure and absolute stereochemistry of the natural product.

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6

Bobeica, Silvia C., Lingyang Zhu, Jeella Z. Acedo, Weixin Tang, and Wilfred A. van der Donk. "Structural determinants of macrocyclization in substrate-controlled lanthipeptide biosynthetic pathways." Chemical Science 11, no. 47 (2020): 12854–70. http://dx.doi.org/10.1039/d0sc01651a.

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To understand factors that determine ring pattern and stereochemistry of thioether cyclization of lanthipeptide natural products, the structures of five prochlorosins (blue) and two enterococcal cytolysins (red) were determined by NMR spectroscopy.

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7

Osei Akoto, Clement, and Jon D. Rainier. "Concise Seven-Membered Oxepene/Oxepane Synthesis – Structural Motifs in Natural and Synthetic Products." Synthesis 51, no. 18 (2019): 3529–35. http://dx.doi.org/10.1055/s-0037-1611838.

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This work outlines a suitable method for the synthesis of oxepane skeleton using iterative C-glycoside technology on the oxepene intermediate, which was synthesized utilizing Wilkinson’s catalyst [Rh(PPh3)3Cl] to generate the isomerized product in a linear synthetic manner. The central core of the oxepene motif was achieved via an olefin metathesis reaction using the Grubbs second-generation and Schrock catalysts. The synthesis of the functionalized oxepane having the desired adriatoxin E-ring relative stereochemistry was achieved starting from commercially available homopropargylic alcohol.

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8

Nasir, Shah Bakhtiar, Noorsaadah Abd Rahman, and Chin Fei Chee. "Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review." Current Organic Synthesis 15, no. 2 (2018): 221–29. http://dx.doi.org/10.2174/1570179414666170821120234.

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Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples.

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9

Irabuena, Camila, Laura Posada, Luciana Rey, et al. "Synthesis of Cyclotetrapeptides Analogues to Natural Products as Herbicides." Molecules 27, no. 21 (2022): 7350. http://dx.doi.org/10.3390/molecules27217350.

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The synthesis of cyclotetrapeptides analogues of the natural products tentoxin and versicotide D was achieved in good yield by solid phase peptide synthesis (SPPS) of their linear precursors and solution phase cyclization. All the cyclopeptides and several open precursors were evaluated as herbicides. Five cyclopeptides and five lineal peptides showed a significant inhibition (>70%) of Ryegrass seed’s radicle growth at 67 μg/mL. The evaluation at lower concentrations (4–11 μM) indicates two cyclopeptides analogs of tentoxin, which present one (N-Methyl-d-Phe), and two N-MeAA (N-Methyl-Ala a

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10

Li, Barbara T. Y., Jonathan M. White, and Craig A. Hutton. "Synthesis of the Leu - Trp Component of the Celogentin Family of Cyclic Peptides Through a C - H Activation - Cross-Coupling Strategy." Australian Journal of Chemistry 63, no. 3 (2010): 438. http://dx.doi.org/10.1071/ch10033.

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A bioinspired approach to the central leucine(C3)–tryptophan(C6) cross-linked moiety present in the celogentin family of cyclic peptide natural products was achieved. The key transformation was enabled through a palladium-catalyzed C–H activation–cross-coupling of leucine quinoline amide and 6-iodotryptophan derivatives. X-Ray crystallographic analysis of a β-(indol-6-yl)-leucine derivative confirms the stereochemistry of the cross-linked adduct matches that of the natural products. The method enables the preparation of the Leu–Trp adduct as a single stereoisomer from l-leucine and l-tryptopha

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11

Pilli, Ronaldo, Franco Della-Felice, Francisco de Assis, and Ariel Sarotti. "Palladium-Catalyzed Formation of Substituted Tetrahydropyrans: Mechanistic Insights and Structural Revision of Natural Products." Synthesis 51, no. 07 (2019): 1545–60. http://dx.doi.org/10.1055/s-0037-1611708.

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A comprehensive study on the stereochemical outcome of palladium-catalyzed formation of 2,4,6-trisubstituted tetrahydropyrans through cyclization of the corresponding allylic acetates using both Pd(0) and Pd(II) catalysts is presented. We have found that the stereochemical outcome of this cyclization is dependent not only on the stereochemistry of the acyclic precursor but also on the nature of the palladium catalyst. These results were applied to the total synthesis of the putative structure of cryptoconcatone H. Experimental and computational DP4+ NMR results were used to assess the structu

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12

Kobayashi, Jun'ichi. "Chemistry and biology of Okinawan marine natural products." Pure and Applied Chemistry 81, no. 6 (2009): 1009–18. http://dx.doi.org/10.1351/pac-con-08-08-22.

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Marine macro- and micro-organisms collected in Okinawa are good sources of compounds with intriguing structures and interesting biological activities. Synthetic hybrid molecules of caffeine and eudistomin D from tunicates Eudistoma sp. were found to show better potency as adenosine receptor ligands than caffeine, and one of them exhibits potent activity for adenosine receptors tested, especially for A3 subtype. Potent cytotoxic polyene macrolides from a tunicate Cystodytes sp. were found to be potent osteoclast inhibitors and to inhibit vacuolar type H+-ATPase (V-ATPase) of both mammalian and

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13

Kolodiazhnyi, Oleg I. "Phosphorus Compounds of Natural Origin: Prebiotic, Stereochemistry, Application." Symmetry 13, no. 5 (2021): 889. http://dx.doi.org/10.3390/sym13050889.

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Organophosphorus compounds play a vital role as nucleic acids, nucleotide coenzymes, metabolic intermediates and are involved in many biochemical processes. They are part of DNA, RNA, ATP and a number of important biological elements of living organisms. Synthetic compounds of this class have found practical application as agrochemicals, pharmaceuticals, bioregulators, and othrs. In recent years, a large number of phosphorus compounds containing P-O, P-N, P-C bonds have been isolated from natural sources. Many of them have shown interesting biological properties and have become the objects of

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14

Zamir, Lolita O., Maria E. Nedea, Zhen-Hua Zhou, et al. "Taxus canadensis taxanes: structures and stereochemistry." Canadian Journal of Chemistry 73, no. 5 (1995): 655–65. http://dx.doi.org/10.1139/v95-084.

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The structures and stereochemistry of 14 taxanes isolated from Taxuscanadensis have been rigorously established by high-resolution NMR techniques and mass spectrometry. Taxuscanadensis is the only yew that accumulates 9-dihydro-13-acetylbaccatin III (also called 7,9-deacetylbaccatin VI) as the most abundant taxane. Five 9-dihydrotaxanes derived from the Canadian yew are novel natural products not reported in the needles of other species of yew (8–11, 14, Fig. 1). Keywords: Taxuscanadensis, Taxaceae, taxanes, 9-dihydro-13-acetylbaccatin III, taxol.

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15

Cotterill, Ann S., and Melvyn Gill. "Synthesis of (S)-(−)-austrocorticin and (S)-(+)-dermolactone: Absolute stereochemistry of the natural products." Tetrahedron Letters 34, no. 19 (1993): 3155–58. http://dx.doi.org/10.1016/s0040-4039(00)93405-1.

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16

Paterson, Danielle L., and David Barker. "Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B." Beilstein Journal of Organic Chemistry 11 (February 17, 2015): 265–70. http://dx.doi.org/10.3762/bjoc.11.29.

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The synthesis of the unique furo[2,3-b]chromene ring system found in hyperaspidinols A and B, acylphloroglucinols from Hypericum chinense has been achieved in twelve steps. By comparison of the NMR spectra of the synthesized compounds with those of the natural products, a relative stereochemistry is suggested, especially that of the ketal carbon.

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17

Suzuki, Keisuke. "Synthetic study of ravidomycin, a hybrid natural product." Pure and Applied Chemistry 72, no. 9 (2000): 1783–86. http://dx.doi.org/10.1351/pac200072091783.

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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

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18

Fairhurst, Magnus, Muhammad Zeeshan, Bengt Haug, and Annette Bayer. "Aldol Condensations on a 3-Alkylidene-2,5-diketopiperazine: Synthesis of Two Marine Natural Products." Synlett 29, no. 10 (2018): 1303–6. http://dx.doi.org/10.1055/s-0036-1591755.

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The synthesis of two marine natural products containing a 3-alkylidene-6-arylidene-2,5-diketopiperazine scaffold by employing two consecutive aldol condensations starting with 1,4-diacetyl-2,5-diketopiperazine is reported. The target compounds contain a phenol or an imidazole group as aryl substituents, respectively, and suitable conditions for the aldol condensation of 1-acyl-3-alkylidene-2,5-diketopiperazine with the required functionalised aromatic aldehydes were developed. Provided the optimal base was used, introduction of the phenol group did not require use of a protecting group. Boc-pr

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19

Majhi, Sasadhar. "The Art of Total Synthesis of Bioactive Natural Products via Microwaves." Current Organic Chemistry 25, no. 9 (2021): 1047–69. http://dx.doi.org/10.2174/1385272825666210303112302.

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Natural products are the most effective source of potential drug leads. The total synthesis of bioactive natural products plays a crucial role in confirming the hypothetical complex structure of natural products in the laboratory. The total synthesis of rare bioactive natural products is one of the great challenges for the organic synthetic community due to their complex structures, biochemical specificity, and difficult stereochemistry. Subsequently, the total synthesis is a long process in several cases, and it requires a substantial amount of time. Microwave irradiation has emerged as a gre

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20

Butler, MS, and RJ Capon. "The Luffarins (A-Z), Novel Terpenes From an Australian Marine Sponge, Luffariella geometrica." Australian Journal of Chemistry 45, no. 10 (1992): 1705. http://dx.doi.org/10.1071/ch9921705.

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A marine sponge, Luffariella geometrica Kirkpatrick, collected from the southern Australian coastal waters of the Great Australian Bight, has been found to contain 14 new bicyclic sesterterpenes, luffarin-A (14), -B (15), -C (16), -D (17), -E (18), -F (19), -G (20), -H (21), -I (22), -J (23), -K (24), -L (25), -M (26) and -N (27), a new bicyclic bisnorsesterterpene, luffarin-O (30), a new monocyclic sesterterpene, luffarin-P (32), six new acyclic sesterterpenes, luffarin-Q (35), -R (36), -S (37), -T (38), -U (39) and -V (40), two new diterpenes, luffarin-W (41) and -X (44), and two new bisnord

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21

Haberz, Peter, Jonathan Farjon, and Christian Griesinger. "A DMSO-Compatible Orienting Medium: Towards the Investigation of the Stereochemistry of Natural Products." Angewandte Chemie International Edition 46, no. 41 (2007): 7730. http://dx.doi.org/10.1002/anie.200790206.

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22

Haberz, Peter, Jonathan Farjon, and Christian Griesinger. "A DMSO-Compatible Orienting Medium: Towards the Investigation of the Stereochemistry of Natural Products." Angewandte Chemie International Edition 44, no. 3 (2005): 427–29. http://dx.doi.org/10.1002/anie.200461267.

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23

Haberz, Peter, Jonathan Farjon, and Christian Griesinger. "A DMSO-Compatible Orienting Medium: Towards the Investigation of the Stereochemistry of Natural Products." Angewandte Chemie 119, no. 41 (2007): 7874. http://dx.doi.org/10.1002/ange.200790206.

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24

Haberz, Peter, Jonathan Farjon, and Christian Griesinger. "A DMSO-Compatible Orienting Medium: Towards the Investigation of the Stereochemistry of Natural Products." Angewandte Chemie 117, no. 3 (2005): 431–33. http://dx.doi.org/10.1002/ange.200461267.

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25

Batchu, Venkateswara Rao, Lingamurthy Macha, Aravind Reddy Dorigundla, Raju Gurrapu та Umamaheswara Sarma Vanka. "Total Synthesis of the Natural Products Ulmoside A and (2R,3R)-Taxifolin-6-C-β-d-glucopyranoside". Synlett 31, № 11 (2020): 1097–101. http://dx.doi.org/10.1055/s-0040-1707971.

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An efficient first total synthesis of highly polar ulmoside A and (2R,3R)-taxifolin-6-C-β-d-glucopyranoside, useful for the prevention of metabolic disorders, has been described. Key elements of the synthesis include a Sc(OTf)3-catalyzed regio- and stereoselective C-glycosidation on taxifolin in 35% yield with d-glucose and chiral semipreparative reverse-phase high-performance liquid chromatography (HPLC) for the separation of both taxifolins and the diastereomeric mixture of taxifolin-6-C-β-d-glucopyranosides. Correlation of the analytical data of synthetic ulmoside A and its diastereomer wit

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26

Buchanan,, Malcolm S., Melvyn Gill, and Jin Yu. "Pigments of Fungi. XLV The Cardinalins 8 - 12, Unique Pre-naphthoquinone Dehydro Dimers from the New Zealand Toadstool Dermocybe cardinalis." Australian Journal of Chemistry 50, no. 11 (1997): 1081. http://dx.doi.org/10.1071/c97110.

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Five new pre-naphthoquinone dehydro dimers (3)–(7) belonging to the unique cardinalin class of pyranonaphthoquinonoid natural products have been isolated and characterized from the ethanolic extracts of the fruit bodies of the New Zealand toadstool Dermocybe cardinalis. Four other cardinalin derivatives (8) and (10)–(12) are believed to be artefacts of the purification procedure. The structures and relative stereochemistry of these new cardinalins are deduced from spectroscopic data.

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27

Ciavatta, M. L. "Application of NMR Technique in the Elucidation of Marine Natural Compounds." Chemistry Journal of Moldova 6, no. 2 (2011): 9–12. http://dx.doi.org/10.19261/cjm.2011.06(2).02.

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The topic of the seminar held in the Institute of Chemistry, Academy of Sciences of Moldova on 30th September in the frame of the joint Moldo-Italian seminar “New frontiers in natural product chemistry”, concerned the use of NMR techniques in the elucidation of natural products. Step by step, two marine compounds (Fulvyne C and Tritoniopsin A) belonging to different chemical classes have been analyzed, by using suitable NMR experiments. This powerful technique allowed the elucidation of compounds as fulvynes, long chain polyacetylenes with the same functional groups but differently located in

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28

Yang, Bei-Bei, Fan Gao, Ya-Dong Yang, Ru Wang, Xin Li, and Li Li. "Stereochemistry of Chiral 2-Substituted Chromanes: Twist of the Dihydropyran Ring and Specific Optical Rotation." Molecules 28, no. 1 (2023): 439. http://dx.doi.org/10.3390/molecules28010439.

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Chiral 2-substituted chromanes are important substructures in organic synthesis and appear in numerous natural products. Herein, the correlation between specific optical rotations (SORs) and the stereochemistry at C2 of chiral 2-substituted chromanes was investigated through data mining, quantum-chemical calculations using density functional theory (DFT), and mechanistic analyses. For 2-aliphatic (including acyloxy and alkenyl) chromanes, the P-helicity of the dihydropyran ring usually corresponds to a positive SOR; however, 2-aryl chromanes with P-helicity tend to exhibit negative SORs. 2-Car

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29

Bowden, BF, JC Coll, and RH Willis. "Studies of Australian Soft Corals. XXXIX. New Sesquiterpene Metabolites From Several Xenia Species (Xeniidae, Octocorallia, Anthozoa)." Australian Journal of Chemistry 39, no. 10 (1986): 1717. http://dx.doi.org/10.1071/ch9861717.

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The structures and absolute stereochemistry of three new metabolites isolated from Xenia species of soft corals have been determined by spectroscopic study and chemical correlation with known natural products. The new metabolites are: (1S,2R,4R,4aS,5Z,8aR)-1,2-epoxy-4-isopropyl-1,6-dimethyl-1,2,3,4,4a,7,8,8a-octahydronaphthalene (4), (1E,4R,4aR,5S,6R,8aR)-5,6-epoxy-4-isopropyl-6-methyl- 3,4,4a,5,6,7,8,8a-octahydronaphthalene-1-methanol acetate (5) and (1E,5Z,4R,4aR,8aR)-4-isopropyl-6-methyl-3,4,4a,7,8,8a- hexahydronaphthalene-1-methanol (6).

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30

Burnell, Robert H., and Stéphane Caron. "Approach to the synthesis of candelabrone and synthesis of 3,7-diketo- 12-hydroxyabieta-8,11,13-triene." Canadian Journal of Chemistry 70, no. 5 (1992): 1446–54. http://dx.doi.org/10.1139/v92-181.

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An approach to the synthesis of aromatic diterpenes was tested for its generality. Phenylacetonitriles with increasing substitution on the aromatic ring were prepared and alkylated with geranyl bromide and the resulting dienes subjected to cationic cyclization. The less-substituted examples afforded tricyclic products of the required stereochemistry while the more highly substituted compounds cyclized with reduced yields or not at all. One of the intermediates was used to synthesize nimosone (3,7-diketo-12-methoxyabieta-8,11,13-triene), a natural diterpene isolated originally from Chamaecypari

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31

Ray, Bimalendu, Martin Schütz, Shuvam Mukherjee, Subrata Jana, Sayani Ray, and Manfred Marschall. "Exploiting the Amazing Diversity of Natural Source-Derived Polysaccharides: Modern Procedures of Isolation, Engineering, and Optimization of Antiviral Activities." Polymers 13, no. 1 (2020): 136. http://dx.doi.org/10.3390/polym13010136.

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Naturally occurring polysaccharide sulfates are highly diverse, owning variations in the backbone structure, linkage pattern and stereochemistry, branching diversity, sulfate content and positions of sulfate group(s). These structural characteristics bring about diverse sulfated polymers with dissimilar negative charge densities and structure–activity relationships. Herein, we start with a short discussion of techniques needed for extraction, purification, chemical sulfation, and structural characterization of polysaccharides. Processes of isolation and sulfation of plant-derived polysaccharid

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32

Kondru, Rama K., Peter Wipf, and David N. Beratan. "Theory-Assisted Determination of Absolute Stereochemistry for Complex Natural Products via Computation of Molar Rotation Angles." Journal of the American Chemical Society 120, no. 9 (1998): 2204–5. http://dx.doi.org/10.1021/ja973690o.

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33

Falk, Michael, Peter F. Spierenburg, and John A. Walter. "Determination of the stereochemistry of natural products from nuclear magnetic resonance data by constrained molecular dynamics." Journal of Computational Chemistry 17, no. 4 (1996): 409–17. http://dx.doi.org/10.1002/(sici)1096-987x(199603)17:4<409::aid-jcc3>3.0.co;2-y.

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34

Cuny, Eckehard. "Stereoselective Synthesis of Spiroacetal Domain Derivatives of the Plant Glycoside Ranuncoside and of Okadaic Acid and Dinophysistoxins-1 and 2 From Marine Algae." Natural Product Communications 15, no. 11 (2020): 1934578X2097115. http://dx.doi.org/10.1177/1934578x20971150.

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Spiroacetals constitute the central structural core element of numerous natural products and are mostly represented as bicyclic or tricyclic domains. Typical natural products with tricyclic spiroacetals are (+)-ranuncoside 1, a glycoside isolated from plants of the Ranuncalaceae family, and the algal toxins (+)-okadaic acid 2 and the (+)-dinophysistoxins-1 and 2 (3 and 4). These substances possess a spiro furan-dioxane-pyran ring system 5 and a spiro furan-pyran-pyran scaffold 6, which are both essential for biological activity. Corresponding analogs with spiro furan-dioxane-cyclohexane framew

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35

Buchanan, Malcolm S., Melvyn Gill, and Alberto Giménez. "Pigments of Fungi. XLVI. New Dimeric Dihydroanthracenones of the Flavomannin Type from an Australian Toadstool of the Genus Dermocybe." Australian Journal of Chemistry 51, no. 2 (1998): 103. http://dx.doi.org/10.1071/c97155.

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cis,cis-4,4′-Dihydroxyflavomannin 6,6′-di-O-methyl ether A (4), 10,10′-dihydroxy-4,4′-dioxoflavomannin 6,6′-di-O-methyl ether A (6) and 4′,10-dihydroxy-4-oxoanhydroflavomannin-9′,10′-quinone 6,6′-di-O-methyl ether A (7), new coupled dihydroanthracenones, and bierythroglaucin (8), a novel dimeric anthraquinone, have been isolated along with emodin (9) and citreorosein (ω-hydroxyemodin) (10) from the purple-brown fruit bodies of the Australian Dermocybe sp. WAT 21566. The structures and relative stereochemistry of the new natural products (4) and (6)–(8) are deduced by spectroscopic and chemical

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36

Kaldre, Dainis, Immo Klose, and Nuno Maulide. "Stereodivergent synthesis of 1,4-dicarbonyls by traceless charge–accelerated sulfonium rearrangement." Science 361, no. 6403 (2018): 664–67. http://dx.doi.org/10.1126/science.aat5883.

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The chemistry of the carbonyl group is essential to modern organic synthesis. The preparation of substituted, enantioenriched 1,3- or 1,5-dicarbonyls is well developed, as their disconnection naturally follows from the intrinsic polarity of the carbonyl group. By contrast, a general enantioselective access to quaternary stereocenters in acyclic 1,4-dicarbonyl systems remains an unresolved problem, despite the tremendous importance of 2,3-substituted 1,4-dicarbonyl motifs in natural products and drug scaffolds. Here we present a broad enantioselective and stereodivergent strategy to access acyc

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37

Humpf, Hans-Ulrich, Nina Berova, Koji Nakanishi, Michael B. Jarstfer, and C. Dale Poulter. "Allylic and Homoallylic CD Exciton Chirality: A Sensitive Method for Determining the Absolute Stereochemistry of Natural Products." Journal of Organic Chemistry 60, no. 11 (1995): 3539–42. http://dx.doi.org/10.1021/jo00116a048.

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38

Achanta, Prabhakar S., Raghuram Rao Akkinepally, Ravi Kumar Bobbala, and Appa Rao V. N. Achanta. "Stereochemistry of 2,2,5-trisubstituted tetrahydrofuran ring-containing natural products based on 1 H NMR spectroscopy: some observations." Magnetic Resonance in Chemistry 54, no. 2 (2015): 158–63. http://dx.doi.org/10.1002/mrc.4329.

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39

Lautens, Mark, Yi Ren, Patrick Delanghe, Pauline Chiu, Shihong Ma, and John Colucci. "1994 Merck Frosst Award Lecture New strategies for the stereoselective synthesis of natural and unnatural products via organometallic reagents and catalysts." Canadian Journal of Chemistry 73, no. 8 (1995): 1251–57. http://dx.doi.org/10.1139/v95-153.

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Samarium in the presence of diiodomethane selectively cyclopropanates an allenic alcohol to yield a methylenecyclopropane with modest to excellent diastereoselectivity. The effect of substituents at the carbinol carbon and the allenic carbon on the diastereoselectivity was investigated. A palladium catalyst was shown to promote the intramolecular cycloaddition of the methylenecyclopropane with an electron-deficient alkyne to yield a methylenecyclopentane. The reaction was stereospecific with retention of stereochemistry as proven by X-ray diffraction. Nickel catalysts accelerate the hydroalumi

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Fuentespina, Ruben Pomar, José Angel Garcia de la Cruz, Gabriel Durin, Victor Mamane, Jean-Marc Weibel та Patrick Pale. "Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes". Beilstein Journal of Organic Chemistry 15 (27 червня 2019): 1416–24. http://dx.doi.org/10.3762/bjoc.15.141.

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1,3-Enynes are important building blocks in organic synthesis and also constitute the key motif in various bioactive natural products and functional materials. However, synthetic approaches to stereodefined substituted 1,3-enynes remain a challenge, as they are limited to Wittig and cross-coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific rearrangemen

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Riccio, R., Giuseppe Bifulco, Paola Cimino, Carla Bassarello, and Luigi Gomez-Paloma. "Stereochemical analysis of natural products. Approaches relying on the combination of NMR spectroscopy and computational methods." Pure and Applied Chemistry 75, no. 2-3 (2003): 295–308. http://dx.doi.org/10.1351/pac200375020295.

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The stereochemical study of flexible stereogenic carbon chains, such as those of many novel natural products, is a particularly challenging task. Recent applications of our group on the so-called "J-based approach", a methodology relying on a detailed analysis of homonuclear (H-H) and heteronuclear (C-H) 2,3J couplings, include the study of the sphinxolide family of antitumor macrolides, a group of molecules characterized by a flexible macrocyclic framework bearing a number of oxygenated and methylated undetermined stereocenters, and of ascaulitoxin, a nitrogen-containing phytotoxin with herbi

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Behr, Jean-Bernard, and Georges Guillerm. "Synthesis of 6-deoxy-homoDMDP and its C(5)-epimer: absolute stereochemistry of natural products from Hyacinthus orientalis." Tetrahedron: Asymmetry 13, no. 2 (2002): 111–13. http://dx.doi.org/10.1016/s0957-4166(02)00081-2.

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Essig, Sebastian, and Dirk Menche. "Stereochemistry and total synthesis of complex myxobacterial macrolides." Pure and Applied Chemistry 85, no. 6 (2013): 1103–20. http://dx.doi.org/10.1351/pac-con-12-09-12.

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Polyketides are a very diverse family of natural products with an extremely broad range of biological activities and pharmacological properties, including antiproliferative, antibiotic, antifungal, or antiplasmodial activities, and in many cases specific targets are addressed at the molecular level. Their structures are characterized by diverse assemblies of methyl- and hydroxyl-bearing stereogenic centers enabling large numbers of stereochemical permutations, which are often embedded into macrolide rings. This complexity renders the stereochemical assignment and directed total synthesis chall

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Kim, Min Cheol, Jaclyn M. Winter, Reiko Cullum, Alexander J. Smith, and William Fenical. "Expanding the Utility of Bioinformatic Data for the Full Stereostructural Assignments of Marinolides A and B, 24- and 26-Membered Macrolactones Produced by a Chemically Exceptional Marine-Derived Bacterium." Marine Drugs 21, no. 6 (2023): 367. http://dx.doi.org/10.3390/md21060367.

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Marinolides A and B, two new 24- and 26-membered bacterial macrolactones, were isolated from the marine-derived actinobacterium AJS-327 and their stereostructures initially assigned by bioinformatic data analysis. Macrolactones typically possess complex stereochemistry, the assignments of which have been one of the most difficult undertakings in natural products chemistry, and in most cases, the use of X-ray diffraction methods and total synthesis have been the major methods of assigning their absolute configurations. More recently, however, it has become apparent that the integration of bioin

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Weinges, Klaus, and Sylke Haremsa. "Chemistry and Stereochemistry of Iridoids, X. Enantiomerically Pure Hexahydropentalene Derivatives – Building Units for the Synthesis of Cyclopentanoid Natural Products." Liebigs Annalen der Chemie 1987, no. 8 (1987): 679–82. http://dx.doi.org/10.1002/jlac.198719870807.

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Huang, Hui, N. Raluca Hurubeanu, Cheryl J. Bourgeois, et al. "Octahedral perfluoroalkyl complexes of Ir(III) formed by oxidative addition of perfluoroalkyl iodides to Ir(acac)(CO)2." Canadian Journal of Chemistry 87, no. 1 (2009): 151–60. http://dx.doi.org/10.1139/v08-114.

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Oxidative addition of primary, secondary, or benzylic perfluoroalkyl iodides (RF–I) to the phosphine free Ir(I) precursor Ir(acac)(CO)2 1 (acac = 2,4-pentanedionato) proceeds smoothly to afford octahedral Ir(III) products Ir(acac)(I)(RF)(CO)2, A combination of X-ray crystallographic studies and solution spectroscopy shows that these products are the result of overall trans-addition of the C–I bond to iridium, probably a result of thermodynamic control; evidence for a kinetic product resulting from net cis-addition is obtained in one case. Treatment of the Ir(III) compounds with AgOTf (Tf = CF3

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Brash, Alan R., William E. Boeglin, Donald F. Stec, Markus Voehler, Claus Schneider, and Jin K. Cha. "Isolation and Characterization of Two Geometric Allene Oxide Isomers Synthesized from 9S-Hydroperoxylinoleic Acid by Cytochrome P450 CYP74C3." Journal of Biological Chemistry 288, no. 29 (2013): 20797–806. http://dx.doi.org/10.1074/jbc.m113.482521.

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Specialized cytochromes P450 or catalase-related hemoproteins transform fatty acid hydroperoxides to allene oxides, highly reactive epoxides leading to cyclopentenones and other products. The stereochemistry of the natural allene oxides is incompletely defined, as are the structural features required for their cyclization. We investigated the transformation of 9S-hydroperoxylinoleic acid with the allene oxide synthase CYP74C3, a reported reaction that unexpectedly produces an allene oxide-derived cyclopentenone. Using biphasic reaction conditions at 0 °C, we isolated the initial products and s

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Cuny, Eckehard, and Franz-Dietrich Klingler. "Efficient Isolation and Structure Analysis of (+)-Ranuncoside, a Unique Tricyclic Spiroacetal Glycoside, from Christmas Rose (Helleborus niger L.)." Natural Product Communications 17, no. 1 (2022): 1934578X2110694. http://dx.doi.org/10.1177/1934578x211069456.

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The use of medicinal herbs as remedies reaches back to the Stone Age, and their importance as a source of drugs has continuously increased since then. Herbal ingredients can serve as active pharmaceuticals themselves or as lead substances for the development of synthetic pharmaceuticals with less toxicity, higher effectiveness or with new properties. To date, only 6% of the ∼600,000 plants on earth have been tested pharmacologically. Among these, the medicinal plant Helleborus niger L. (Christmas rose) is especially promising because its leaves contain ( + )-ranuncoside 1, characterized by a s

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Stonik, Valentin A., and Sophia A. Kolesnikova. "Malabaricane and Isomalabaricane Triterpenoids, Including Their Glycoconjugated Forms." Marine Drugs 19, no. 6 (2021): 327. http://dx.doi.org/10.3390/md19060327.

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In this review, we discuss structural diversity, taxonomic distribution, biological activities, biogenesis, and synthesis of a rare group of terpenoids, the so-called malabaricane and isomalabaricane triterpenoids, as well as some compounds derived from them. Representatives of these groups were found in some higher and lower terrestrial plants, as well as in some fungi, and in a relatively small group of marine sponges. The skeletal systems of malabaricanes and isomalabaricanes are similar to each other, but differ principally in the stereochemistry of their tricyclic core fragments, consisti

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Yang, Tao, Chengjie Huang, Jingyang Jia, Fan Wu, and Feng Ni. "A Facile Synthesis of 2-Oxazolines via Dehydrative Cyclization Promoted by Triflic Acid." Molecules 27, no. 24 (2022): 9042. http://dx.doi.org/10.3390/molecules27249042.

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2-oxazolines are common moieties in numerous natural products, pharmaceuticals, and functional copolymers. Current methods for synthesizing 2-oxazolines mainly rely on stoichiometric dehydration agents or catalytic dehydration promoted by specific catalysts. These conditions either generate stoichiometric amounts of waste or require forcing azeotropic reflux conditions. As such, a practical and robust method that promotes dehydrative cyclization while generating no byproducts would be attractive to oxazoline production. Herein, we report a triflic acid (TfOH)-promoted dehydrative cyclization o

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