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Journal articles on the topic 'Construction of Heterocyclic and Carbocyclic Rings'

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Author: Grafiati

Published: 6 September 2023

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1

Cardoso, Ana L., and Maria I. L. Soares. "1,3-Dipolar Cycloadditions Involving Allenes: Synthesis of Five-Membered Rings." Current Organic Chemistry 23, no. 27 (January 15, 2020): 3064–134. http://dx.doi.org/10.2174/1385272823666191203122959.

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The 1,3-dipolar cycloaddition reaction is a powerful and versatile strategy for the synthesis of carbocyclic and heterocyclic five-membered rings. Herein, the most recent developments on the [3+2] cycloaddition reactions using allenes acting either as dipolarophiles or 1,3-dipole precursors, are highlighted. The recent contributions on the phosphine- and transition metal-catalyzed [3+2] annulations involving allenes as substrates are also covered, with the exception of those in which the formation of a 1,3-dipole (or synthetic equivalent) is not invoked. This review summarizes the most relevant research in which allenes are used as building blocks for the construction of structurally diverse five-membered rings via [3+2] annulation reactions.

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2

Grillo, Alessandro, and Bruno Mattia Bizzarri. "Catalytic Enantioselective Diels Alder Reaction: Application in the Synthesis of Antiviral Agents." Catalysts 12, no. 2 (January 25, 2022): 150. http://dx.doi.org/10.3390/catal12020150.

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The Diels–Alder reaction (DAR) is one of the most effective and reliable strategies for the construction of six-membered carbocyclic and heterocyclic rings, and it is widely used in the synthesis of organic molecules and drugs. Due to the high regio- and stereo-selectivity and its versatility, DARs have represented a powerful tool for organic chemistry for many years. In addition, the asymmetric DAR has become a fundamental synthetic approach in the preparation of optically active six-membered rings and natural compounds. The COVID-19-related pandemic requires continuous research; DAR represents an useful method to obtain optically active intermediates for the synthesis of antiviral agents under different catalytic conditions. We would like to highlight an intriguing synthetic procedure applied to the development of novel synthetic protocols that are potentially useful against a large panel of viruses and other unmet diseases.

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3

Bognár, Balázs, Györgyi Úr, Cecília Sár, Olga H. Hankovszky, Kálmán Hideg, and Tamás Kálai. "Synthesis and Application of Stable Nitroxide Free Radicals Fused with Carbocycles and Heterocycles." Current Organic Chemistry 23, no. 4 (May 22, 2019): 480–501. http://dx.doi.org/10.2174/1385272823666190318163321.

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Stable nitroxide free radicals have traditionally been associated with 2,2,6,6- tetramethylpiperidine-1-oxyl (TEMPO) or its 4-substituted derivatives as relatively inexpensive and readily accessible compounds with limited possibilities for further chemical modification. Over the past two decades, there has been a resurgence of interest in stable free radicals with proper functionalization tuned for various applications. The objective of this review is to present recent results with synthetic methodologies to achieve stable nitroxide free radicals fused with aromatic carbocycles and heterocycles. There are two main approaches for accessing stable nitroxide free radicals fused with arenes, e.g., isoindoline- like nitroxides: further functionalization and oxidation of phthalimide or inventive functionalization of pyrroline nitroxide key compounds. The latter also offers the constructions of versatile heterocyclic scaffolds (furan, pyrrole, thiophene, 1,2-thiazole, selenophene, pyrazole, pyrimidine, pyridine, pyridazine, 1,5-benzothiazepine) that are fused with pyrroline or tetrahydropyridine nitroxide rings. The possible applications of these new stable nitroxide free radicals, such as covalent spin labels and noncovalent spin probes of proteins and nucleic acids, profluorescent probes, building blocks for construction of dual active drugs and electroactive materials, and substances for controlled free radical polymerization, are discussed.

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4

Trost, Barry M., Zhongxing Huang, and Ganesh M. Murhade. "Catalytic palladium-oxyallyl cycloaddition." Science 362, no. 6414 (November 1, 2018): 564–68. http://dx.doi.org/10.1126/science.aau4821.

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Exploration of intermediates that enable chemoselective cycloaddition reactions and expeditious construction of fused- or bridged-ring systems is a continuous challenge for organic synthesis. As an intermediate of interest, the oxyallyl cation has been harnessed to synthesize architectures containing seven-membered rings via (4+3) cycloaddition. However, its potential to access five-membered skeletons is underdeveloped, largely due to the thermally forbidden (3+2) pathway. Here, the combination of a tailored precursor and a Pd(0) catalyst generates a Pd-oxyallyl intermediate that cyclizes with conjugated dienes to produce a diverse array of tetrahydrofuran skeletons. The cycloaddition overrides conventional (4+3) selectivity by proceeding through a stepwise pathway involving a Pd-allyl transfer and ring closure sequence. Subsequent treatment of the (3+2) adducts with a palladium catalyst converts the heterocycles to the carbocyclic cyclopentanones.

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5

Cha, J. K., and J. Oh. "[4 + 3] Cycloaddition Reactions of Cyclic Oxyallyls in Natural Product Synthesis." Current Organic Chemistry 2, no. 3 (May 1998): 217–32. http://dx.doi.org/10.2174/1385272802666220128192145.

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The [4 + 3] cycloadditions of oxyallyls and related allyl cations to 1,3-dienes have been widely utilized for the stereocontrolled construction of seven-membered carbocycles. By virtue of the spectator skeleton, the key variant of utilizing cyclic oxyallyls, i.e., by embedding an oxyallyl function in cyclic compounds, provides a conceptually attractive and operationally efficient route to other medium-sized carbocycles and heterocycles in addition to seven-membered rings. The resulting architecturally complex, polycyclic cycloadducts contain not only sufficient functionality, but also well defined facial differentiation useful for subsequent elaboration.

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6

Chen, Feng-Zheng, Qing-Xiang Xiang, Yuan-Qin Zhang, and Jun-Ru Xiong. "(1β,2α,3α,7α,11α,13β)-1,3,7,11-Tetraacetoxy-2,13-bis(benzyloxy)-21-methyl-19,21-secohetisan-19-al hemihydrate." Acta Crystallographica Section E Structure Reports Online 65, no. 6 (May 29, 2009): o1432. http://dx.doi.org/10.1107/s1600536809018315.

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In the crystal structure of the title compound, C43H46NO13·0.5H2O, the molecule assumes a U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The molecule contains eight alicyclic and heterocyclic rings. The cyclohexane rings adopt chair conformations, the other three six-membered carbocyclic rings form a bicyclo[2.2.2]octane system with a boat conformation for each six-membered ring, the six-membered heterocyclic ring has a chair conformation and both of the five-membered rings have envelope conformations. The solvent water molecule links with the organic moleculeviaclassic O—H...O and weak C—H...O hydrogen bonding in the crystal structure.

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7

Boyd, Derek R., Narain D. Sharma, Ludmila V. Modyanova, Jonathan G. Carroll, John F. Malone, Christopher CR Allen, John TG Hamilton, David T. Gibson, Rebecca E. Parales, and Howard Dalton. "Dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems." Canadian Journal of Chemistry 80, no. 6 (June 1, 2002): 589–600. http://dx.doi.org/10.1139/v02-062.

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Toluene dioxygenase-catalyzed dihydroxylation, in the carbocyclic rings of quinoline, 2-chloroquinoline, 2-methoxyquinoline, and 3-bromoquinoline, was found to yield the corresponding enantiopure cis-5,6- and -7,8-dihy dro diol metabolites using whole cells of Pseudomonas putida UV4. cis-Dihydroxylation at the 3,4-bond of 2-chloroquino line, 2-methoxyquinoline, and 2-quinolone was also found to yield the heterocyclic cis-dihydrodiol metabolite, (+)-cis-(3S,4S)-3,4-dihydroxy-3,4-dihydro-2-quinolone. Heterocyclic cis-dihydrodiol metabolites, resulting from dihydroxylation at the 5,6- and 3,4-bonds of 1-methyl 2-pyridone, were isolated from bacteria containing toluene, naphthalene, and biphenyl dioxygenases. The enantiomeric excess (ee) values (>98%) and the absolute configurations of the carbocyclic cis-dihydrodiol metabolites of quinoline substrates (benzylic R) and of the heterocyclic cis-diols from quinoline, 2-quinolone, and 2-pyridone substrates (allylic S) were found to be in accord with earlier models for dioxygenase-catalyzed cis-dihydroxylation of carbocyclic arenes. Evidence favouring the dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems is presented.Key words: dioxygenases; cis-dihydroxylation, pyridines, 2-pyridones, absolute configurations.

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8

Taticchi, Aldo, Lucio Minuti, Daniela Lanari, Assunta Marrocchi, Ilaria Tesei, and Eszter Gacs-Baitz. "Synthesis of helical [2.2]paracyclophanes containing carbocyclic and heterocyclic five-membered rings." Tetrahedron 60, no. 51 (December 2004): 11759–64. http://dx.doi.org/10.1016/j.tet.2004.09.114.

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9

Liu, Yuxiao, Yu Liu, Charles S. Shanahan, Xichen Xu, and Michael P. Doyle. "A survey of enoldiazo nucleophilicity in selective C–C bond forming reactions for the synthesis of natural product-like frameworks." Org. Biomol. Chem. 12, no. 28 (2014): 5227–34. http://dx.doi.org/10.1039/c4ob00709c.

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10

Yadav, Deepak, and Rajeev S. Menon. "Recent developments in the chemistry of allenyl sulfones." Organic & Biomolecular Chemistry 18, no. 3 (2020): 365–78. http://dx.doi.org/10.1039/c9ob01912j.

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Allenyl sulfones are versatile building blocks for the construction of various acyclic, carbocyclic and heterocyclic motifs. Recent developments in the preparation and synthetic applications of allenyl sulfones are summarised.

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11

Hirst, Gavin C., Paul N. Howard, and Larry E. Overman. "Stereocontrolled construction of carbocyclic rings by sequential cationic cyclization-pinacol rearrangements." Journal of the American Chemical Society 111, no. 4 (February 1989): 1514–15. http://dx.doi.org/10.1021/ja00186a065.

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12

Biswas, Swapan Kumar. "Recent development of Silver-catalyzed Oxo- and Aza cyclization." International Journal of Experimental Research and Review 26 (December 30, 2021): 90–98. http://dx.doi.org/10.52756/ijerr.2021.v26.007.

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This article addresses new developments in silver-catalyzed cyclization processes, resulting in the formation of carbocyclic or heterocyclic rings. Some essential techniques in organic chemistry include silver-catalyzed reactions. In addition, silver catalysts have been emerged as a novel catalysis in the last two decades. In these sequences, preparations of oxygen and nitrogen-containing heterocyclic compounds emerge as the most important development of new methodology. Silver catalysts exhibit significant reactivity in mild conditions in contrast to other transition metals such as copper, lead, zinc, ruthenium, gallium, indium, and niobium. These developments have lots of scientific attention due to their potential to synthesise of heterocyclic compounds in medicinal and agrochemical use. This current literature review summarises several silver-catalyzed oxo and aza-cyclization processes using readily available starting materials.

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13

Xuan, Jun, Liang-Qiu Lu, Jia-Rong Chen, and Wen-Jing Xiao. "Visible-Light-Driven Photoredox Catalysis in the Construction of Carbocyclic and Heterocyclic Ring Systems." European Journal of Organic Chemistry 2013, no. 30 (July 9, 2013): 6755–70. http://dx.doi.org/10.1002/ejoc.201300596.

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14

de Andrade, Vitor, and Marcio de Mattos. "N-Halo Reagents: Modern Synthetic Approaches for Heterocyclic Synthesis." Synthesis 51, no. 09 (March 27, 2019): 1841–70. http://dx.doi.org/10.1055/s-0037-1611746.

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Heterocyclic chemistry is an essential frontier in science and a source of novel biologically active compounds. The development of innovative synthetic methodologies that allows access to different heterocyclic rings is of critical interest to the scientific community. This review will focus on recent applications of N-halo compounds (e.g., N-halosuccinimides, trihaloisocyanuric acids, N-halosulfonamides, etc.) in heterocyclic construction via electrophilic cyclization, asymmetric halocyclization, oxidative cyclization, and radical processes.1 Introduction2 N-Halo Reagent Mediated Heterocyclic Construction and Functionalization2.1 Electrophilic Halocyclizations2.1.1 Asymmetric Halocyclizations2.2 Radical Halocyclizations2.3 Oxidative Halocyclizations2.4 Miscellaneous Halocyclization Reactions3 Summary and Outlook

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15

Michaut, Antoine, and Jean Rodriguez. "Selective Construction of Carbocyclic Eight-Membered Rings by Ring-Closing Metathesis of Acyclic Precursors." Angewandte Chemie International Edition 45, no. 35 (September 4, 2006): 5740–50. http://dx.doi.org/10.1002/anie.200600787.

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16

Ashfeld, Brandon L., and Zachary D. Tucker. "(4+1)-Cycloadditions Exploiting the Biphilicity of Oxyphosphonium Enolates and RhII/PdII-Stabilized Metallocarbenes for the Construction of Five-Membered Frameworks." Synlett 32, no. 12 (January 26, 2021): 1157–68. http://dx.doi.org/10.1055/s-0040-1706009.

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Abstract(4+1)-Cyclizations are an underutilized disconnect for the formation of five-membered heterocyclic and carbocyclic frameworks. Herein we analyze methods employing oxyphosphonium enolates and RhII/PdII-metallocarbenes as C1 synthons in the presence of several four-atom components for the synthesis of 2,3-dihydrobenzofurans, 2,3-dihydroindoles, oxazolones, cyclopentenones, and pyrrolones.1 Introduction2 (4+1)-Cyclizations Employing Kukhtin–Ramirez-Like Reactivity3 (4+1)-Cyclizations Employing a Cyclopropanation/Ring-Expansion Sequence4 Pd-Catalyzed (4+1)-Cyclizations through Carbene Migratory Insertion/Reductive Elimination Processes5 Summary

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17

Loska, Rafał, and Mieczysław Mąkosza. "Introduction of Carbon Substituents into Nitroarenes via Nucleophilic Substitution of Hydrogen: New Developments." Synthesis 52, no. 21 (June 18, 2020): 3095–110. http://dx.doi.org/10.1055/s-0040-1707149.

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Nucleophilic substitution of hydrogen in nitroarenes has become a powerful synthetic tool for functionalization of these important organic substrates, complementary to other modern methods. In this review we present new developments in the area of introduction of alkyl and functionalized alkyl substituents into nitroarene rings via nucleophilic substitution of hydrogen, followed by application of these processes in the construction of carbo- and heterocyclic rings. Finally, new developments in the investigation of the mechanism of SNArH are summarized.1 Introduction2 Alkylation and Haloalkylation3 Functionalized Carbon Substituents4 Formation of Carbo- and Heterocyclic Rings5 Mechanistic Aspects of SNArH6 Conclusion

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18

Xuan, Jun, Liang-Qiu Lu, Jia-Rong Chen, and Wen-Jing Xiao. "ChemInform Abstract: Visible-Light-Driven Photoredox Catalysis in the Construction of Carbocyclic and Heterocyclic Ring Systems." ChemInform 45, no. 1 (December 12, 2013): no. http://dx.doi.org/10.1002/chin.201401252.

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19

Maji, Pradip Kumar. "Synthesis of Pyrimidine-Annulated Five-Membered Heterocycles: An Overview." Current Organic Chemistry 23, no. 20 (December 24, 2019): 2204–69. http://dx.doi.org/10.2174/1385272823666191019111627.

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This review describes the non-exhaustive scenery of the synthesis of various biologically interesting pyrimidine annulated five-membered heterocyclic ring systems that have been appeared in the literature during the last two decades. During this period, different synthetic routes and various methodologies have been developed for the functionalization of pyrimidine ring towards the construction of five-membered heterocyclic rings. The aim of this review is to give an overview of the assorted methodologies that have been reported about the chemistry of construction of pyrimidines annulated nitrogen, oxygen and sulphur containing five-membered heterocycles.

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20

Soares, Maria I. L., Ana L. Cardoso, and Teresa M. V. D. Pinho e Melo. "Diels–Alder Cycloaddition Reactions in Sustainable Media." Molecules 27, no. 4 (February 15, 2022): 1304. http://dx.doi.org/10.3390/molecules27041304.

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Diels–Alder cycloaddition reaction is one of the most powerful strategies for the construction of six-membered carbocyclic and heterocyclic systems, in most cases with high regio- and stereoselectivity. In this review, an insight into the most relevant advances on sustainable Diels–Alder reactions since 2010 is provided. Various environmentally benign solvent systems are discussed, namely bio-based derived solvents (such as glycerol and gluconic acid), polyethylene glycol, deep eutectic solvents, supercritical carbon dioxide, water and water-based aqueous systems. Issues such as method’s scope, efficiency, selectivity and reaction mechanism, as well as sustainability, advantages and limitations of these reaction media, are addressed.

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21

Ojima, Iwao. "New cyclization reactions in organic syntheses." Pure and Applied Chemistry 74, no. 1 (January 1, 2002): 159–66. http://dx.doi.org/10.1351/pac200274010159.

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Recent development in the transition metal-catalyzed cyclization reactions for organic syntheses in the author's laboratories is summarized, which includes (i) novel silylcarbocyclizations (SiCaCs) and carbonylative carbotricyclizations, (ii) intramolecular silylformylations and desymmerization of siloxydiynes by sequential double silylformylation, (iii) efficient total synthesis of (+)-prosopinine, (iv) enantioselective desymmetrization of aminodienes, and (iv) new and efficient routes to 1-azabicyclo[x.y.0]alkane amino acids. All these processes are catalyzed by Rh or RhCo complexes, and useful for rapid and efficient construction of a variety of heterocyclic and carbocyclic compounds. Mechanisms of these new carbocyclization and cyclohydrocarbonylation reactions are also discussed.

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22

Jandl, Christian, and Alexander Pöthig. "Dimerization of a mixed-carbene PdII dibromide complex by elemental iodine." Acta Crystallographica Section C Structural Chemistry 73, no. 12 (November 24, 2017): 1131–36. http://dx.doi.org/10.1107/s2053229617016412.

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A monomeric PdII complex bearing a mixed carbocyclic/N-heterocyclic carbene ligand and two bromides was reacted with an excess of elemental iodine, which resulted in the surprising removal of one bromide ligand and dimerization of the mixed-carbene complex to form di-μ-bromido-bis{[1-(cyclohepta-2,4,6-trien-2-yl-1-ylidene-κC 1)-3-(2,6-diisopropylphenyl)imidazol-2-ylidene]palladium(II)} bis(pentaiodide) dichloromethane monosolvate, [Pd2Br2(C22H24N2)2](I5)2·CH2Cl2. The dimeric complex features a slightly distorted square-planar core of two PdII centres bridged by two bromide ligands, which lie in the same plane as the seven- and five-membered rings of the bidentate carbene ligand. The counter-ions in the single crystal were found to be pentaiodide monoanions featuring their typical V-shape, whereas for the bulk material, a mixture of Br/I interhalides is proposed.

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23

Pellissier, Hélène. "The Use of Domino Reactions for the Synthesis of Chiral Rings." Synthesis 52, no. 24 (July 22, 2020): 3837–54. http://dx.doi.org/10.1055/s-0040-1707905.

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This short review highlights the recent developments reported in the last four years on the asymmetric construction of chiral rings based on enantioselective domino reactions promoted by chiral metal catalysts.1 Introduction2 Formation of One Ring Containing One Nitrogen Atom3 Formation of One Ring Containing One Oxygen/Sulfur Atom4 Formation of One Ring Containing Several Heterocyclic Atoms5 Formation of One Carbon Ring6 Formation of Two Rings7 Conclusion

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24

Kitamura, Masato, Kengo Miyata, Tomoaki Seki, Namdev Vatmurge, and Shinji Tanaka. "CpRu-catalyzed asymmetric dehydrative allylation." Pure and Applied Chemistry 85, no. 6 (April 15, 2013): 1121–32. http://dx.doi.org/10.1351/pac-con-12-10-02.

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Asymmetric Tsuji–Trost allylation is one of the key chiral technologies for construction of pharmaceutically important compounds because of the high utility of alkenyl-substituted products. Particularly, the dehydrative system using allylic alcohols and protic nucleophiles has started to attract the attention of organic synthetic chemists from the viewpoints of atom and step economy, environmental benignity, and operational simplicity. In this paper, two types of new chiral CpRu catalysts, which have been developed on the basis of redox-mediated donor–acceptor bifunctional catalyst (RDACat) concept, are presented. Complementary use of the chiral catalysts has realized the syntheses of a wide rage of carbocyclic compounds, saturated N- or O-heterocyclic compounds with high reactivity, regioselectivity, enantioselectivity, productivity, and generality.

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25

Zard, Samir Z. "The xanthate route to six-membered carbocycles." Journal of Chemical Research 46, no. 2 (March 2022): 174751982210881. http://dx.doi.org/10.1177/17475198221088194.

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Convergent routes to various six-membered carbocyclic architectures exploiting the unique radical chemistry of xanthates are described in this brief review. Three approaches are discussed. The first is the modification of existing cyclohexane building blocks, namely, cyclohexanones, cyclohexenones and cyclohexenes. The second deals with the construction of six-membered carbocycles by associating the chemistry of xanthates with classical ionic reactions, especially the Robinson annulation, the Michael addition and the Horner–Wadsworth–Emmons condensation. Finally, the third route is the formation of six-membered rings by direct six- exo and, but more rarely, six- endo cyclisation modes. Many of the complex structures presented herein would be tedious to obtain by more traditional methods.

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26

Lin, Wei-Yu, Karthick Govindan, Tamilselvan Duraisamy, Alageswaran Jayaram, and Gopal Chandru Senadi. "Copper-Catalyzed Oxidative Cyclization of 2-Aminobenzamide Derivatives: Efficient Syntheses of Quinazolinones and Indazolones." Synthesis 54, no. 04 (October 12, 2021): 1115–24. http://dx.doi.org/10.1055/a-1667-3977.

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AbstractA simple copper-catalyzed assembly to formulate quinazolinone and indazolone derivatives in a single protocol manner is reported. These transformations are based on the fact that DMF can serve as a reaction solvent and one carbon synthon for the construction of heterocyclic rings. Moreover, this protocol features base-free and Brønsted acid free environmentally benign conditions with broad synthetic scope. A good scalability is demonstrated.

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27

Hua, Ruimao. "Isoquinolone Syntheses by Annulation Protocols." Catalysts 11, no. 5 (May 11, 2021): 620. http://dx.doi.org/10.3390/catal11050620.

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Isoquinolones (isoquinolin-1(2H)-ones) are one of the important nitrogen-heterocyclic compounds having versatile biological and physiological activities, and their synthetic methods have been recently developed greatly. This short review illustrates the significant advances in the construction of isoquinolone ring with atom- and step-economy, focusing on the intermolecular annulation protocols and intramolecular cyclization in the presence of a variety of catalyst systems. The syntheses of isoquinolone-fused rings are also included.

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28

Sbei, Najoua, Anna V. Listratova, Alexander A. Titov, and Leonid G. Voskressensky. "Recent Advances in Electrochemistry for the Synthesis of N-Heterocycles." Synthesis 51, no. 12 (May 7, 2019): 2455–73. http://dx.doi.org/10.1055/s-0037-1611797.

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The construction of N-heterocyclic rings represents a very important and fast-developing area of organic synthesis. In this context, electrochemistry has emerged as a mild solution for generating in situ the required electrophilic substrates, bases and nucleophiles derived from low-level and extremely stable reagents, the further application of which makes some heterocycles more accessible. In this review, we have covered the recent advances in the electrochemical synthesis of five- and six-membered N-heterocyclic compounds published from 2017 to October 2018.1 Introduction2 Electrochemical Synthesis of Five-Membered N-Containing Heterocycles2.1 Pyrrolidines2.2 Imidazoles2.3 Pyrazoles2.4 Triazoles2.5 Oxazoles2.6 Indoles2.7 Thiazoless3 Electrochemical Synthesis of Six-Membered N-Containing Heterocycles3.1 Piperidines and Pyridines3.2 Quinazolinones3.3 Benzoxazines4 Conclusions

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29

Ito, Hideto, Tomoya Harada, Hirohisa Ohmiya, and Masaya Sawamura. "Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold–triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization." Beilstein Journal of Organic Chemistry 7 (July 8, 2011): 951–59. http://dx.doi.org/10.3762/bjoc.7.106.

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The gold-catalyzed, seven-membered ring forming, intramolecular hydroamination of alkynic sulfonamides has been investigated. The protocol, with a semihollow-shaped triethynylphosphine as a ligand for gold, allowed the synthesis of a variety of azepine derivatives, which are difficult to access by other methods. Both alkynic sulfoamides with a flexible linear chain and the benzene-fused substrates underwent 7-exo-dig cyclization to afford the nitrogen-containing heterocyclic seven-membered rings, such as tetrahydroazepine and dihydrobenzazepine, in good yields.

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30

Kawada, Hatsuo, Mitsuhiro Iwamoto, Masayuki Utsugi, Masayuki Miyano, and Masahisa Nakada. "Synthetic Studies on the Taxane Skeleton: Construction of Eight-Membered Carbocyclic Rings by the IntramolecularB-Alkyl Suzuki−Miyaura Cross-Coupling Reaction." Organic Letters 6, no. 24 (November 2004): 4491–94. http://dx.doi.org/10.1021/ol0481939.

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31

Li, Yang, Yan-peng Li, Jun He, Ding Liu, Qi-zhi Zhang, Kang Li, Xing Zheng, Guo-Tao Tang, Yu Guo, and Yunmei Liu. "The Relationship between Pharmacological Properties and Structure- Activity of Chrysin Derivatives." Mini-Reviews in Medicinal Chemistry 19, no. 7 (March 28, 2019): 555–68. http://dx.doi.org/10.2174/1389557518666180424094821.

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Chrysin is a natural product of a flavonoid compound. Chemically, chrysin consists of two phenyl rings (A and B) and a heterocyclic ring (C). Biologically, chrysin exerts many different physiological activities. In recent years, with the in-depth development for more active drugs, the synthesis and biological activities of chrysin derivatives have been well studied. Besides, structure-activity relationship of chrysin revealed that the chemical construction meets the critical chemical structural necessities of flavonoids for numerous pharmacological activities. It is generally believed that modified chrysin could be more potent than unmodified chrysin. Different modification in the rings of chrysin could possess various degrees of biological activities. This review aims to summarize the mechanism for the activities of chrysin and its derivatives in different rings. We also explored the relationship between biological function and structure-activity of substituted chrysin derivatives with different functional groups. The influence of chrysin derivatives on the proliferation and apoptosis of cancer cells is also investigated. Development of novel drugs based on the biological functions of chrysin could better improve clinical outcomes of affected population, especially for tumor patients and diabetic patients.

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32

Faheem, Mohd, Anjani K. Tiwari, and Vinay K. Singh. "A Review on Modern Synthetic Route for the Construction of 1, 3-Diazanaphthalene Moiety." Current Organic Chemistry 24, no. 10 (August 11, 2020): 1108–38. http://dx.doi.org/10.2174/1385272824999200528124440.

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Quinazoline is an organic heterocyclic molecule in which two six-membered aromatic rings are fused. Two nitrogen atoms are present in the quinazoline molecule at 1 and 3 positions that is why it is also known as 1,3-diazanaphthalene. The presence of these two nitrogen atoms in 1,3-diazanaphthalene increases the usefulness of this molecule in the field of pharmaceutical sciences. Many reactions have been reported to prepare 1,3- diazanaphthalene by aminobenzonitrile, o-aminobenzohydrazide, aminobenzamide, aminoacetophenone, and aminobenzoketone under different solvent conditions, but condensation of anthranilic acid with an aromatic aldehyde is the most common method. Later, metal-free and solvent-free conditions dominated over the old methods. This review describes the synthesis of 1,3-diazanaphthalene under different metal catalysts, reagents, solvent- free conditions and under microwave radiation through nucleophilic substitution reaction, condensation, and aromatization. In biological sciences, 1,3-diazanaphthalene derivatives have got an important place due to their ability to bind to different target sites and subsequent discovery of many drug structures.

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Lelyukh, M. I. "Biological activity of heterocyclic systems based on functionally substituted 1,3,4-thia(oxa)diazoles (a review)." Farmatsevtychnyi zhurnal, no. 6 (December 21, 2019): 43–53. http://dx.doi.org/10.32352/10.32352/0367-3057.6.19.05.

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1,3,4-Thiadiazole and oxadiazole hetetocycles are well-known pharmacophore scaffolds, which possess wide possibility for chemical modification and identified diverse pharmacological potential. Such essential and many-sided activities let to consider the mentioned heterocycles as ones of the crucial for expression of pharmacological activity, which confirm their importance for medicinal chemistry. Moreover, 1,3,4-oxadiazole cycle is a bioisostere for carboxylic, amide and ester groups, which mostly contribute to enhancement the pharmacological activity by participating in hydrogen bonding interactions with different enzymes and receptors. The aim of the work was analysis of literature data about biological activity of non-condensed heterocyclic systems based on 1,3,4-thia(oxa)diazole rings as promising objects for modern bioorganic and medicinal chemistry. In this study are presented the analysis of actual literature data about pharmacological activity of heterocyclic systems based on 1,3,4-thiadiazole. It has been established that mentioned scaffolds were identified as the main structural component of biological agents with antimicrobial, anti-inflammatory, analgetic, antitumor antitubercular and antiviral activity. Moreover, the combination of 1,3,4-thiadiazole or 1,3,4-oxadiazole core with various heterocycles led to synergistic effect in many cases. Thus, mentioned scaffolds are important heterocyclic fragments that are considered as promising structural matrices for the construction of new drug-likes molecules. An analysis of the biological activity of 1,3,4-thia(oxa)diazole derivatives was carried out, which allowed to confirm their versatile pharmacological potential. Obtained data can be considered as background for further in-depth studies of chemical and pharmacological properties such heterocyclic systems with possible application in medicine.

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Duc, Dau Xuan. "Recent Progress in the Synthesis of Benzo[b]thiophene." Current Organic Chemistry 24, no. 19 (December 1, 2020): 2256–71. http://dx.doi.org/10.2174/1385272824999200820151545.

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: Benzo[b]thiophenes are aromatic heterocyclic compounds containing benzene and thiophene rings. This class of heterocycles is present in a large number of natural and non-natural compounds. Benzo[b]thiophene derivatives have a broad range of applications in medicinal chemistry such as antimicrobial, anticancer, antioxidant, anti-HIV and antiinflammatory activities. The use of benzo[b]thiophene derivatives in other fields has also been reported. Various benzo[b]thiophenes compounds have been employed as organic photoelectric materials, while several benzo[b]thiophenes have been used as organic semiconductors. Benzo[b]thiophenes have also been used as building blocks or intermediates for the synthesis of pharmaceutically important molecules. : Due to such a wide range of applicability, the synthesis of benzo[b]thiophene derivatives has attracted intensive research. Numerous mild and efficient approaches for the synthesis of benzo[b]thiophenes have been developed over the years. Different catalysts and substrates have been applied for benzo[b]thiophene synthesis. This review will focus on the studies in the construction of benzo[b]thiophene skeleton, which date back from 2012.

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Dai, Xiaoyu, Yuanen Ma, Linzhou Zhang, Zhiming Xu, Xuewen Sun, and Suoqi Zhao. "Optimization of Molecular Composition Distribution of Slurry Oil by Supercritical Fluid Extraction to Improve the Structure and Performance of Mesophase Pitch." Energies 15, no. 19 (September 25, 2022): 7041. http://dx.doi.org/10.3390/en15197041.

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The composition distribution of slurry oil has a significant impact on the structure and performance of the mesophase. In this study, supercritical fluid extraction oil (SFEO) and extraction components were extracted from two slurry oils (SLOs) using the supercritical fluid extraction (SFE) technique. The fundamental properties and composition distribution of two SLOs and associated SFEOs were thoroughly investigated. Electron microscopy and spectroscopic techniques were employed to study the morphology and structures of mesophase pitch produced by carbonizing SLOs and their extraction components under the same conditions. The findings revealed that, compared to SLO–LH, SLO–SH has a higher proportion of 4–5 aromatic rings and a narrower hydrocarbon distribution range. In SLO–LH, O1, N1, and N1O1 molecules with long side chains and poor flatness make up the majority of the heterocyclic aromatic hydrocarbons. The distribution of CH compounds can be narrowed by using supercritical fluid extraction to efficiently separate various heteroatom-containing compounds with a higher condensation degree. After supercritical extraction, the mesophase content, texture distribution, and graphitization degree of the mesophase were improved. Polycyclic aromatic hydrocarbons with high planarity help polymer macromolecules stick together and build up in an orderly way. Heterocyclic aromatic hydrocarbons with high condensation and low planarity, on the other hand, play an important role in the formation of mosaic structures.

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Duc, Dau Xuan. "Recent Achievement in the Synthesis of Benzo[b]furans." Current Organic Synthesis 17, no. 7 (October 28, 2020): 498–517. http://dx.doi.org/10.2174/1570179417666200625212639.

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Background: Benzo[b]furan derivatives are oxygen-containing heterocyclic compounds consisting of fused benzene and furan rings and are present in a large number of natural and non-natural compounds. This class of compounds has a wide spectrum of biological activities, such as antiarrhythmic, anticancer, inflammatory, antioxidant, antimicrobial, and antiviral. Furthermore, benzo[b]furan derivatives have also been applied in various areas, such as organic electroluminescence device materials and organic dyes, photosensitizing material, organic synthesis as building blocks or intermediates. : Because of a broad range of applicability, the synthesis of benzo[b]furan derivative has drawn great attention of chemists and many studies on the synthesis of this class of compounds have been reported recently. This review will give an overview of benzo[b]furan preparation based on studies dating back to the year 2012. Objective: In this review, recent development in the synthesis of benzo[b]furans are discussed. There has been increasingly new methodologies for the construction of benzo[b]furans skeleton to improve efficiency or develop environmentally friendly procedures. In some studies, reaction mechanisms were also outlined. Conclusion: Many methods for the synthesis of benzo[b]furans have been reported recently. Most of them involve cyclization or cycloisomerization processes. Unquestionably, more imaginative strategies for the construction of benzo[b]furan skeleton will be established in the near future. Application of known methods to natural products or drug synthesis, on industrial scale for the synthesis of economically or medicinally important benzo[ b]furans will probably be paid attention to.

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Sedenkova, Kseniya N., Olga V. Ryzhikova, Svetlana A. Stepanova, Alexei D. Averin, Sergei V. Kositov, Yuri K. Grishin, Igor P. Gloriozov, and Elena B. Averina. "Bis(oxiranes) Containing Cyclooctane Core: Synthesis and Reactivity towards NaN3." Molecules 27, no. 20 (October 14, 2022): 6889. http://dx.doi.org/10.3390/molecules27206889.

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Reactions of oxirane ring opening provide a powerful tool for regio- and stereoselective synthesis of polyfunctional and heterocyclic compounds, widely used in organic chemistry and drug design. Cyclooctane, alongside other medium-sized rings, is of interest as a novel molecular platform for the construction of target-oriented leads. Additionally, cyclooctane derivatives are well known to be prone to transannular reactions, which makes them a promising object in the search for novel approaches to polycyclic structures. In the present work, a series of cyclooctanediones was studied in Corey-Chaykovsky reactions, and novel spirocyclic bis(oxiranes) containing cyclooctane core, namely, 1,5-dioxadispiro[2.0.2.6]dodecane and 1,8-dioxadispiro[2.3.2.3]dodecane, were synthesized. Ring opening of the obtained bis(oxiranes) upon treatment with sodium azide was investigated, and it was found that the reaction path is determined by the reciprocal orientation of oxygen atoms in the oxirane moieties. Diastereomers of the bis(oxiranes) with cis-orientation underwent independent ring opening, supplying corresponding diazidodiols, while in the case of stereoisomers with trans-orientation, domino-like reactions occurred, including intramolecular nucleophilic attack and the formation of a novel three- or six-membered O-containing ring. Summarily, a straightforward approach to polyfunctional compounds containing cyclooctane or oxabicyclo[3.3.1]nonane cores, employing bis(oxiranes), was elaborated.

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Barange, Deepak Kumar, Venkateswara Rao Batchu, Dhillirao Gorja, Vijaya Raghavan Pattabiraman, Lakshmi Kumar Tatini, J. Moses Babu, and Manojit Pal. "Regioselective construction of six-membered fused heterocyclic rings via Pd/C-mediated C–C coupling followed by iodocyclization strategy: a new entry to 2H-1,2-benzothiazine-1,1-dioxides." Tetrahedron 63, no. 8 (February 2007): 1775–89. http://dx.doi.org/10.1016/j.tet.2006.12.040.

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39

Blanco, Maria C., Alirio Palma, Justo Cobo, and Christopher Glidewell. "Nine closely related tetrahydro-1,4-epoxy-1-benzazepines carrying pendant heterocyclic substituents: hydrogen-bonded supramolecular assembly in zero, one and two dimensions." Acta Crystallographica Section C Crystal Structure Communications 68, no. 3 (February 24, 2012): o131—o140. http://dx.doi.org/10.1107/s010827011200707x.

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The structures are reported of nine closely related tetrahydro-1,4-epoxy-1-benzazepines carrying pendant heterocyclic substituents, namely: 2-exo-(5-nitrofuran-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C14H12N2O4, (I), 7-fluoro-2-exo-(1-methyl-1H-pyrrol-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H15FN2O, (II), 7-fluoro-2-exo-(5-methylfuran-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H14FNO2, (III), 7-fluoro-2-exo-(3-methylthiophen-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H14FNOS, (IV), 7-fluoro-2-exo-(5-methylthiophen-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H14FNOS, (V), 7-chloro-2-exo-(5-methylfuran-2-yl)-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H14ClNO2, (VI), 2-exo-(5-methylfuran-2-yl)-7-trifluoromethoxy-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C16H14F3NO3, (VII), 2-exo-(3-methylthiophen-2-yl)-7-trifluoromethoxy-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C16H14F3NO2S, (VIII), and 2-exo-(5-nitrofuran-2-yl)-7-trifluoromethoxy-2,3,4,5-tetrahydro-1,4-epoxy-1H-1-benzazepine, C15H11F3N2O5, (IX). All nine compounds crystallize in centrosymmetric space groups as racemic mixtures with configuration (2RS,4SR). There are no direction-specific interactions between the molecules in (V). The molecules in (III), (IV), (VI) and (VII) are linked into simple chains, by means of a single C—H...O hydrogen bond in each of (III), (VI) and (VII), and by means of a single C—H...π(arene) hydrogen bond in (IV), while the molecules in (VIII) are linked into a chain of rings. In each of (I) and (II), a combination of one C—H...O hydrogen bond and one C—H...π(arene) hydrogen bond links the molecules into sheets, albeit of completely different construction in the two compounds. In (IX), the sheet structure is built from a combination of four independent C—H...O hydrogen bonds and one C—H...π(arene) hydrogen bond. Comparisons are made with some related compounds.

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40

Huang, Qiu-Ying, Yang Zhao, and Xiang-Ru Meng. "Syntheses, structures and characterization of isomorphous CoII and NiII coordination polymers based on 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole and benzene-1,4-dicarboxylate." Acta Crystallographica Section C Structural Chemistry 73, no. 8 (July 31, 2017): 645–51. http://dx.doi.org/10.1107/s2053229617010877.

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Careful choice of the organic ligands is one of the most important parameters in the rational design and synthesis of coordination polymers. Aromatic polycarboxylates have been widely used in the preparation of metal–organic polymers since they can utilize various coordination modes to form diverse structures and can act as hydrogen-bond acceptors and donors in the assembly of supramolecular structures. Nitrogen-heterocyclic organic compounds have also been used extensively as ligands for the construction of polymers with interesting structures. In the polymers catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN 3}cobalt(II)]-μ2-benzene-1,4-dicarboxylato-κ2 O 1:O 4] dihydrate], {[Co(C8H4O4)(C12H11N4)2(H2O)2]·2H2O} n , (I), and catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN 3}nickel(II)]-μ2-benzene-1,4-dicarboxylato-κ2 O 1:O 4] dihydrate], {[Ni(C8H4O4)(C12H11N4)2(H2O)2]·2H2O} n , (II), the CoII or NiII ion lies on an inversion centre and exhibits a slightly distorted octahedral coordination geometry, coordinated by two N atoms from two imidazole rings and four O atoms from two monodentate carboxylate groups and two water molecules. The dicarboxylate ligands bridge metal ions forming a polymeric chain. The 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole ligands coordinate to the CoII or NiII centres in monodentate modes through an imidazole N atom and are pendant on opposite sides of the main chain. The two structures are isomorphous. In the crystal, the one-dimensional chains are further connected through O—H...O, O—H...N and N—H...O hydrogen bonds, leading to a three-dimensional supramolecular architecture. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviours and fluorescence properties of both polymers have been investigated.

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41

Abomelha, Hanna. "Synthesis of novel dyes based on thiophene analogues with antibacterial activity for dyeing polyester fabrics." Pigment & Resin Technology 48, no. 4 (July 1, 2019): 337–47. http://dx.doi.org/10.1108/prt-02-2018-0012.

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Purpose This study aims to the synthesis of some novel 4-arylazo-3-hydroxythiophene analogues containing sulphapyridine and sulphathiazole dyestuffs and studying their application in dyeing polyester fabrics and rendering their antibacterial efficacy. Design/methodology/approach Simultaneous dyeing and antibacterial finishing for polyester fabric using a new antibacterial disperse dye having a modified chemical structure to thiophene dyes were studied. Construction of the thiophene dyes was carried out by diazo-coupling of diazotized sulphonamide-containing heterocyclic rings sulphapyridine and sulphathiazole with ethyl α-phenylthiocarbamoyl-acetoacetate followed by cyclizing the produced 2-arylazo-thioacetanilide with various α-halogenated reagents. All newly synthesized compounds were characterized by elemental analysis and extensive study of their spectral data (IR and 1H-NMR). The dyeing characteristics of these thiophene dyestuffs were evaluated at optimum conditions. Antibacterial activities of the obtained thiophene dyes were studied against some Gram-positive and Gram-negative bacteria. Findings The synthesized thiophene-containing sulphonamides dyes were applied on polyester fabric. The modified dyes exhibited a good fastness properties and antibacterial efficacy against some Gram-positive and Gram-negative bacteria. Synthesized dyes showed higher antibacterial potency than the reference standard drug. Research limitations/implications Synthesis of these disperse azo dyes for textile dyeing had never been reported previously. Practical implications The dyestuffs derived from thiophene are reasonable azo disperse dyestuffs giving good all-round fastness properties on polyester fabrics. Originality/value Thiophene dyes are used for dyeing polyester fabrics with brilliant colour and good fastness properties. The presence of sulphonamides moieties increase their fastness properties and elevate their antibacterial properties. Moreover, they can be used as antimicrobial finish due to their bactericidal properties on dyed textiles. This work afforded a new thiophene colorant that can be used in many different uses like polyester packing, thread Surgery, blends and other uses in medical textile.

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42

Zhang, Cai, Demao Chen, Jie-Ping Wan, and Yunyun Liu. "Recent Advances in Electrochemical Cascade Cyclization Reactions." Synthesis, February 20, 2023. http://dx.doi.org/10.1055/a-2039-1728.

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This review highlights the recent progress in the electrochemical cascade cyclization reactions for the synthesis of carbon rings and heterocycles such as pyridines, quinolines, phenanthridines, cinnolines, 1,4-dihydroquinolines, oxindoles, imidazo[1,5-a]pyridines, imidazoles, etc. The works included herein are introduced in tow major sections of heterocycle construction and carbocycle construction reactions, covering the works reported from 2012 to 2022.

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43

Huo, Hengrui, and Yuefa Gong. "Construction of heterocyclic rings from cyclopropenes." Organic & Biomolecular Chemistry, 2022. http://dx.doi.org/10.1039/d1ob02450g.

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Highly strained cyclopropenes are valuable functional building blocks in the construction of heterocyclic skeletons, which are highly appealing due to their wide and important applications in synthetic chemistry and medicinal...

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44

Ajavakom, Vachiraporn, Potchanee Pandokrak, Sofia S. Salim, Gamal A. I. Moustafa, Richard K. Bellingham, Joseph T. Hill-Cousins, Anawat Ajavakom, and Richard Brown. "Formation of seven-membered rings by RCM of vinyl bromides." Synlett, May 6, 2022. http://dx.doi.org/10.1055/a-1845-4195.

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Grubbs II catalyst mediated ring-closing metathesis (RCM) of mono-brominated dienes is reported to proceed in moderate to good yields (40–80%) where the linking chain contains five atoms, leading to carbocyclic and heterocyclic 7-membered bromo-olefins. Notably, RCM to form 5-, 6- or 8-membered bromo-olefins was unsuccessful, with the exception of one example where RCM afforded diethyl 3-bromocyclohex-3-ene-1,1-dicarboxylate. In this case a bromomethyl-substituted cyclohexene was obtained as a byproduct. The utility of selected bromo-olefin RCM products was demonstrated through their participation in Suzuki-Miyaura reactions. Vinyl halide exchange (BrCl) was noted as a side reaction under RCM conditions.

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45

HIRST, G. C., P. N. HOWARD, and L. E. OVERMAN. "ChemInform Abstract: Stereocontrolled Construction of Carbocyclic Rings by Sequential Cationic Cyclization-Pinacol Rearrangements." ChemInform 20, no. 23 (June 6, 1989). http://dx.doi.org/10.1002/chin.198923107.

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46

Zhang, Xuntong, Chenpeng Gao, and James P. Morken. "Enantioselective Construction of Carbocyclic and Heterocyclic Tertiary Boronic Esters by Conjunctive Cross-Coupling Reaction." Journal of the American Chemical Society, July 24, 2023. http://dx.doi.org/10.1021/jacs.3c05815.

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47

Sinnwell, Michael A., Ryan H. Groeneman, Benjamin J. Ingenthron, Changan Li, and Leonard R. MacGillivray. "Supramolecular construction of a cyclobutane ring system with four different substituents in the solid state." Communications Chemistry 4, no. 1 (May 10, 2021). http://dx.doi.org/10.1038/s42004-021-00493-3.

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AbstractMethods to form cyclobutane rings by an intermolecular [2 + 2] cross-photoreaction (CPR) with four different substituents are rare. These reactions are typically performed in the liquid phase, involve multiple steps, and generate product mixtures. Here, we report a CPR that generates a cyclobutane ring with four different aryl substituents. The CPR occurs quantitatively, without side products, and without a need for product purification. Generally, we demonstrate how face-to-face stacking interactions of aromatic rings can be exploited in the process of cocrystallization and the field of crystal engineering to stack and align unsymmetrical alkenes in CPRs to afford chiral cyclobutanes with up to four different aryl groups via binary cocrystals. Overall, we expect the process herein to be useful to generate chiral carbon scaffolds, which is important given the presence of four-membered carbocyclic rings as structural units in biological compounds and materials science.

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48

Castagnolo, Daniele, Fei Zhao, Domiziana Masci, and Elena Tomarelli. "Biocatalytic and Chemo-Enzymatic Approaches for the Synthesis of Heterocycles." Synthesis, July 28, 2020. http://dx.doi.org/10.1055/s-0040-1707210.

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Heterocycles are ubiquitous structures in nature and can be found in many drugs and chemicals. Biocatalysts, alone or in combination with other metal catalysts, can be exploited for the construction of various heterocyclic rings under mild reaction conditions. This Short Review highlights the recent advances in the development of biocatalytic and chemo-enzymatic methods for the synthesis of both aliphatic and aromatic heterocyclic rings.1 Introduction2 Synthesis of Aliphatic Heterocycles2.1 Piperidines, Pyrrolidines and Piperazines2.2 Other Nitrogen-Containing Aliphatic Heterocycles2.3 Lactones and Lactams2.4 Other Oxygen-Containing Heterocycles3 Synthesis of Aromatic Heterocycles3.1 Pyrroles, Pyridines and Pyrazines3.2 Furans3.3 Bicyclic Aromatic Heterocycles4 Conclusion

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Hou, Meifeng, Jiajun Li, Fucai Rao, Zuliang Chen, and Yingjing Wei. "Diastereoselective Synthesis of Tetrahydrobenzo[b]azocines by Lu(OTf)3 Catalyzed [4 + 4] Cycloaddition of Donor–Acceptor Cyclobutanes with Anthranils." Chemical Communications, 2022. http://dx.doi.org/10.1039/d2cc00829g.

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The construction of N-heterocyclic eight-membered rings remains a challenging due to unfavorable transannular strain. Herein, we report a Lu(OTf)3 catalyzed formal [4 +4] cycloaddition reaction of cyclobutane 1,1-diesters with anthranils...

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50

Flores, Daniel M., Michael L. Neville, and Valerie A. Schmidt. "Intermolecular 2+2 imine-olefin photocycloadditions enabled by Cu(I)-alkene MLCT." Nature Communications 13, no. 1 (May 19, 2022). http://dx.doi.org/10.1038/s41467-022-30393-6.

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Abstract2 + 2 Photocycloadditions are idealized, convergent construction approaches of 4-membered heterocyclic rings, including azetidines. However, methods of direct excitation are limited by the unfavorable photophysical properties of imines and electronically unbiased alkenes. Here, we report copper-catalyzed photocycloadditions of non-conjugated imines and alkenes to produce a variety of substituted azetidines. Design principles allow this base metal-catalyzed method to achieve 2 + 2 imine-olefin photocycloaddition via selective alkene activation through a coordination-MLCT pathway supported by combined experimental and computational mechanistic studies.

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