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Journal articles on the topic 'C–N atropisomers'

Author: Grafiati

Published: 30 November 2024

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1

Xiao, Xiao, Biao Chen, Yi-Ping Yao, Hai-Jie Zhou, Xu Wang, Neng-Zhong Wang, and Fen-Er Chen. "Construction of Non-Biaryl Atropisomeric Amide Scaffolds Bearing a C–N Axis via Enantioselective Catalysis." Molecules 27, no. 19 (October 4, 2022): 6583. http://dx.doi.org/10.3390/molecules27196583.

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The significant scaffold offered by atropisomeric amides with a C–N chiral axis has been extensively utilized for pharmaceuticals, agricultural science, and organic syntheses. As a result, the field of atropisomer synthesis has attracted considerable interest within chemistry communities. To date, a range of catalytic atroposelective approaches has been reported for the efficient construction of these challenging scaffolds. However, greatly concise and highly useful methodologies for the synthesis of these atropisomeric compounds, focusing on transition-metal, chiral amine, and phosphoric acid catalysis reactions, etc., are still desirable. Hence, it is indispensable to succinctly and systematically present all such reports by means of disclosing the mechanistic analysis and application, as well as the challenges and issues associated with the establishment of these atropisomers. In this review, we summarize the development of catalytic asymmetric synthetic strategies to access non-biaryl atropisomers rotating around a C–N chiral axis, including the reaction methods, mechanism, late-stage transformations, and applications.

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2

Bonne, Damien, and Jean Rodriguez. "Enantioselective syntheses of atropisomers featuring a five-membered ring." Chemical Communications 53, no. 92 (2017): 12385–93. http://dx.doi.org/10.1039/c7cc06863h.

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If six-membered ring biaryl or heterobiaryl atropisomers are the most common ones, the focus of this feature article will be put on the enantioselective approaches towards five-membered ring containing atropisomers displaying either a stereogenic C–N- or C–C bond.

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3

Wang, Donglei, Qianwen Jiang, and Xiaoyu Yang. "Atroposelective synthesis of configurationally stable nonbiaryl N–C atropisomers through direct asymmetric aminations of 1,3-benzenediamines." Chemical Communications 56, no. 46 (2020): 6201–4. http://dx.doi.org/10.1039/d0cc02368j.

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4

Faisca Phillips, Ana Maria, and Armando J. L. Pombeiro. "Atropselective Organocatalytic Synthesis of Chiral Compounds Containing Nitrogen along the Axis of Chirality." Symmetry 15, no. 6 (June 15, 2023): 1261. http://dx.doi.org/10.3390/sym15061261.

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Atropisomers, i.e., stereoisomers that are distinct because their free rotation about a single bond is hindered by steric interactions between nearby bulky groups or by electrostatics, may interact with their surroundings in different ways, and may also exhibit different properties. They may be found as natural products, as pharmaceutical or agricultural active ingredients, as chiral ligands and organocatalysts, and in functional materials. Our ability to synthesize them stereoselectively and in a sustainable way, using achiral materials and simply with the aid of an organocatalyst and mild conditions, has become a hot topic in research. This review provides an overview of recent achievements in the synthesis of atropisomers containing C-N and N-N axes of chirality.

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5

Jiayong, Zhang, and Liu Xin-Yuan. "Single-Step Synthesis of Atropisomers with Vicinal C—C and C—N Diaxes via Cobalt-Catalyzed C—H Activation." Chinese Journal of Organic Chemistry 42, no. 11 (2022): 3899. http://dx.doi.org/10.6023/cjoc202200062.

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6

Monteiro, Carlos J. P., Mariette M. Pereira, Nuno P. F. Gonçalves, Carla G. Carvalho, Ângela C. B. Neves, Artur R. Abreu, Luis G. Arnaut, and Artur M. S. Silva. "Separation and atropisomer isolation of ortho-halogenated tetraarylporphyrins by HPLC: Full characterization using 1D and 2D NMR." Journal of Porphyrins and Phthalocyanines 16, no. 03 (March 2012): 316–23. http://dx.doi.org/10.1142/s1088424612500368.

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The separation and isolation of the four atropisomers of ortho-halogenated tetraarylporphyrins by semi-preparative HPLC is described. Full characterization and assignment of all 1 H and 13 C resonances of 5,10,15,20-tetrakis(2-fluoro or 2-chlorophenyl)porphyrins and 5,10,15,20-tetrakis(2-fluoro or chloro-5-N-ethylsulfamoylphenyl)porphyrins by 1D and 2D NMR techniques is reported. The outcome is an unequivocal evidence of the chlorosulfonation of meso-tetra(2-haloaryl)porphyrins on the 5′-position.

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7

Jia, Zhen-Sheng, Yong-Jie Wu, Qi-Jun Yao, Xue-Tao Xu, Kun Zhang, and Bing-Feng Shi. "Pd(II)-Catalyzed Atroposelective C–H Allylation: Synthesis of Enantioenriched N-Aryl Peptoid Atropisomers." Organic Letters 24, no. 1 (December 29, 2021): 304–8. http://dx.doi.org/10.1021/acs.orglett.1c03967.

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8

Wu, Yong-Jie, Pei-Pei Xie, Gang Zhou, Qi-Jun Yao, Xin Hong, and Bing-Feng Shi. "Atroposelective synthesis of N-aryl peptoid atropisomers via a palladium(ii)-catalyzed asymmetric C–H alkynylation strategy." Chemical Science 12, no. 27 (2021): 9391–97. http://dx.doi.org/10.1039/d1sc01130h.

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9

Hasegawa, Futoshi, Kazushi Kawamura, Hiroshi Tsuchikawa, and Michio Murata. "Stable C–N axial chirality in 1-aryluracil scaffold and differences in in vitro metabolic clearance between atropisomers of PDE4 inhibitor." Bioorganic & Medicinal Chemistry 25, no. 16 (August 2017): 4506–11. http://dx.doi.org/10.1016/j.bmc.2017.06.042.

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10

Bain, Alex D., Hao Chen, and Paul H. M. Harrison. "Studies of structure and dynamics in a nominally symmetric twisted amide by NMR and electronic structure calculations." Canadian Journal of Chemistry 84, no. 3 (March 1, 2006): 421–28. http://dx.doi.org/10.1139/v06-016.

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Amides that are twisted around the C—N bond show unusual spectroscopy and reactivity when compared with planar amides. The diacyl derivatives of 3,4,7,8-tetramethyl-2,5-dithioglycoluril are intriguing examples of this class, since the crystal structures show that the two acyl groups are twisted by different amounts on either side of the molecule owing to a combination of steric and electronic effects. However, the 1H NMR spectra in solution at room temperature exhibit only one acyl resonance, so there must be fast interconversion among pairs of equivalent structures of each compound. We have prepared a number of derivatives with different acyl groups, both on the glycoluril framework as well as on its dithio analogue. The chemical exchange in solution was slowed down sufficiently by cooling to see individual sites for only two compounds: the dithiodipivaloyl and the dithiodiadamantyl derivatives. The barriers were estimated at 41 kJ mol–1 for the dipivaloyl derivative and 45 kJ mol–1 for diadamantyl derivative. The results show that rotation around the twisted amide bond is slowed by both the steric size of the acyl group and the presence of the thioureido group vs. the ureido group in the glycoluril core. In the solid-state 13C NMR spectra, there is no evidence for any dynamics, even for the diacetyl derivative at ambient temperature. Electronic structure calculations predict a geometry for the dipivaloyl derivative very close to that observed in the crystal structure. These results indicate that the crystal confines, but does not distort the molecule. A mechanism for the exchange is proposed. The relevance of these results to the mechanism of Claisen-like condensations in diacylglycolurils is also discussed.Key words: 1H and 13C NMR, exchange, dynamics, CP/MAS, solids, line shape analysis, amides, twisted amides, atropisomers, glycoluril.

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11

Knipe, Peter C., and Jamie S. Sweet. "Catalytic Enantioselective Synthesis of C–N Atropisomeric Heterobiaryls." Synthesis 54, no. 09 (February 23, 2022): 2119–32. http://dx.doi.org/10.1055/s-0040-1719896.

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AbstractMolecules containing an atropisomeric C–N biaryl axis are gaining increasing attention in catalytic and medicinal chemistry. Despite this rising interest, relatively few approaches towards their catalytic enantioselective synthesis have been reported. Here we review these approaches, with a focus on the mechanism of asymmetric induction. Some common themes emerge: Brønsted acid catalysed cyclo-condensation and palladium-catalysed ring-closure are the most common and successful approaches. Meanwhile, the more direct but challenging axial C–N bond formation strategy remains in its infancy, with just two reports to-date. We hope this review will inform and inspire other researchers to develop new creative approaches to this important chemical motif.1 Introduction2 Cyclo-Condensation3 Proximal C–N Bond Formation4 Desymmetrisation of Intact Axes5 ortho-C–H Functionalisation6 Cycloaddition7 Axial C–N Bond Formation8 Atropisomeric N–N Axes: An Emerging Class of Heterobiaryls9 Conclusion and Outlook

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12

McCormick, Theresa M., Qinde Liu, and Suning Wang. "Luminescent Atropisomeric N,N-Chelating Ligands from Copper-Catalyzed One-Pot C−N and C−C Coupling Reactions." Organic Letters 9, no. 21 (October 2007): 4087–90. http://dx.doi.org/10.1021/ol701485a.

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13

Chen, Yao-Zhong, Teng Liu, Jie Zhu, Hui Zhang, and Lei Wu. "Transition-metal-free radical cleavage of a hydrazonyl N–S bond: tosyl radical-initiated cascade C(sp3)–OAr cleavage, sulfonyl rearrangement and atropisomeric cyclopropanation." Organic Chemistry Frontiers 5, no. 24 (2018): 3567–73. http://dx.doi.org/10.1039/c8qo00873f.

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Combination of 1,10-phenanthroline and potassium carbonate enables a radical cleavage of a hydrazonyl N–S bond, allowing a coupling reaction of N-tosylhydrazone and phosphinyl allene via cascade C–O cleavage, sulfonyl rearrangement and atropisomeric cyclopropanation.

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14

Said, Awad I., and Talaat I. El-Emary. "Diastereoselective synthesis of atropisomeric pyrazolyl pyrrolo[3,4-d]isoxazolidines via pyrazolyl nitrone cycloaddition to facially divergent maleimides: intensive NMR and DFT studies." RSC Advances 10, no. 2 (2020): 845–50. http://dx.doi.org/10.1039/c9ra10039c.

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Diastereoselective pyrazole-based atropisomeric cycloadducts were formed by cycloaddition of a pyrazole-based nitrone and maleimides with restricted rotation around C–N bond caused by bulk ortho substitution.

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15

Köster, Roland, Günther Seidel, Susanna Kerschl, and Bernd Wrackmeyer. "Atropisomerism in Boron-Nitrogen Heterocycles/Atropisomerism in Boron-Nitrogen Heterocycles." Zeitschrift für Naturforschung B 42, no. 2 (February 1, 1987): 191–94. http://dx.doi.org/10.1515/znb-1987-0212.

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Abstract Atropisomerism owing to hindered rotation about the N-aryl bond is observed in 4,5-diethyl-2,2,3-trimethyl-1-(o-trifluormethyl)phenyl-2,5-dihydro-1H-1,2,5-azasila-(2) and -azastanna-boroles (5). The compounds 2 and 5 are characterized by elemental analysis, mass spectra and 1H, 11B, 13 C, 29Si and119Sn NMR. The ortho-trifluoromethyl group serves as an additional NMR spectroscopic probe because of “through space” 19F-1H and 19F-13C spin spin coupling. Compound 5 is the first derivative of a 2,5-dihydro-1H-1,2,5-azastannaborol.

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16

Takahashi, Isao, Yuya Suzuki, and Osamu Kitagawa. "Asymmetric Synthesis of Atropisomeric Compounds with an N‒C Chiral Axis." Organic Preparations and Procedures International 46, no. 1 (January 2014): 1–23. http://dx.doi.org/10.1080/00304948.2014.866467.

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17

Li, Zhaojie, and Shouyun Yu. "Asymmetric synthesis of atropisomeric compounds with C–N chiral axis." SCIENTIA SINICA Chimica 50, no. 5 (April 22, 2020): 509–25. http://dx.doi.org/10.1360/ssc-2019-0168.

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18

Fan, Xiaozhong, Xue Zhang, Chunyu Li, and Zhenhua Gu. "Enantioselective Atropisomeric Anilides Synthesis via Cu-Catalyzed Intramolecular Adjacent C–N Coupling." ACS Catalysis 9, no. 3 (January 31, 2019): 2286–91. http://dx.doi.org/10.1021/acscatal.8b04789.

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19

Ototake, Nobutaka, Yudai Morimoto, Ayano Mokuya, Haruhiko Fukaya, Yasuo Shida, and Osamu Kitagawa. "Catalytic Enantioselective Synthesis of Atropisomeric Indoles with an NC Chiral Axis." Chemistry - A European Journal 16, no. 23 (May 12, 2010): 6752–55. http://dx.doi.org/10.1002/chem.201000243.

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20

Chiba, Arisa, Ryoko Tanaka, Mayuno Hotta, Kayo Nakamura, Kosho Makino, Hidetsugu Tabata, Tetsuta Oshitari, Hideaki Natsugari, and Hideyo Takahashi. "Stereochemistry of N-Acyl-5H-dibenzo[b,d]azepin-7(6H)-ones." Molecules 28, no. 12 (June 13, 2023): 4734. http://dx.doi.org/10.3390/molecules28124734.

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The stereochemical properties of N-acyl-5H-dibenzo[b,d]azepin-7(6H)-ones (2a–c), which inhibit potassium channels in T cells, were examined by freezing their conformational change due to 4-methyl substitution. N-Acyl-5H-dibenzo[b,d]azepin-7(6H)-ones exist as pairs of enantiomers [(a1R, a2R), (a1S, a2S)], and each atropisomer is separable at room temperature. An alternate procedure for preparing 5H-dibenzo[b,d]azepin-7(6H)-ones involves the intramolecular Friedel–Crafts cyclization of N-benzyloxycarbonylated biaryl amino acids. Consequently, the N-benzyloxy group was removed during the cyclization reaction to produce 5H-dibenzo[b,d]azepin-7(6H)-ones suitable for the subsequent N-acylation reaction.

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21

Shi, Bing-Feng, and Françoise Colobert. "Perfect control of C–N atropisomeric axis for creating high-added-value compounds." Chem Catalysis 1, no. 3 (August 2021): 485–87. http://dx.doi.org/10.1016/j.checat.2021.07.008.

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22

Takahashi, Isao, Yuya Suzuki, and Osamu Kitagawa. "ChemInform Abstract: Asymmetric Synthesis of Atropisomeric Compounds with an N-C Chiral Axis." ChemInform 45, no. 14 (March 21, 2014): no. http://dx.doi.org/10.1002/chin.201414248.

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23

Möhrle, H., and M. Jeandrée. "Darstellung und Atropisomerie von 1-[2-(2,2-Dimethylpiperidino)phenyl]ethanol." Scientia Pharmaceutica 69, no. 1 (March 30, 2001): 1–10. http://dx.doi.org/10.3797/scipharm.aut-01-01.

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The title compound was prepared by Hg(II)-edta dehydrogenation of the aminoalkohol 2 via the benzoxazine 4, which reacted with methylmagnesiumiodide to 6. This compound shows in the NMR spectrum atropisomerism for the restricted rotation of the piperidine moiety about the aryl-C-N bond. The dehydrogenation of 6 stopped after a two electron withdrawal generating the benzoxazine 7, because the angular hydrogen atom occupies an equatorial position, which prevents stereoelectronic conditions for a further oxidation.

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24

Takahashi, Isao, Fumika Morita, Shunsuke Kusagaya, Haruhiko Fukaya, and Osamu Kitagawa. "Catalytic enantioselective synthesis of atropisomeric 2-aryl-4-quinolinone derivatives with an N–C chiral axis." Tetrahedron: Asymmetry 23, no. 24 (December 2012): 1657–62. http://dx.doi.org/10.1016/j.tetasy.2012.11.004.

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25

Takeshita, Hitoshi, Akira Mori, Yukari Ikeda, and Nobuo Kato. "C–N Bond Atropisomerism of 1-(2,4-Dimethyl-3-pentyl)cyclohepta[b]pyrrol-2(1H)-one." Chemistry Letters 19, no. 12 (December 1990): 2199–200. http://dx.doi.org/10.1246/cl.1990.2199.

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26

Matsui, Ryosuke, Erina Niijima, Tomomi Imai, Hiroyuki Kobayashi, Akiko Hori, Azusa Sato, Yuko Nakamura, and Osamu Kitagawa. "Intermolecular Halogen Bond Detected in Racemic and Optically Pure N-C Axially Chiral 3-(2-Halophenyl)quinazoline-4-thione Derivatives." Molecules 27, no. 7 (April 6, 2022): 2369. http://dx.doi.org/10.3390/molecules27072369.

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The halogen bond has been widely used as an important supramolecular tool in various research areas. However, there are relatively few studies on halogen bonding related to molecular chirality. 3-(2-Halophenyl)quinazoline-4-thione derivatives have stable atropisomeric structures due to the rotational restriction around an N-C single bond. In X-ray single crystal structures of the racemic and optically pure N-C axially chiral quinazoline-4-thiones, we found that different types of intermolecular halogen bonds (C=S⋯X) are formed. That is, in the racemic crystals, the intermolecular halogen bond between the ortho-halogen atom and sulfur atom was found to be oriented in a periplanar conformation toward the thiocarbonyl plane, leading to a syndiotactic zig-zag array. On the other hand, the halogen bond in the enantiomerically pure crystals was oriented orthogonally toward the thiocarbonyl plane, resulting in the formation of a homochiral dimer. These results indicate that the corresponding racemic and optically pure forms in chiral molecules are expected to display different halogen bonding properties, respectively, and should be separately studied as different chemical entities.

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27

Zhang, Kan, Yuqi Liu, Zhikun Shang, Corey Evans, and Shengfu Yang. "Effects of End-Caps on the Atropisomerization, Polymerization, and the Thermal Properties of ortho-Imide Functional Benzoxazines." Polymers 11, no. 3 (March 1, 2019): 399. http://dx.doi.org/10.3390/polym11030399.

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A new type of atropisomerism has recently been discovered in 1,3-benzoxazines, where the intramolecular repulsion between negatively charged oxygen atoms on the imide and the oxazine ring hinders the rotation about the C–N bond. The imide group offers a high degree of flexibility for functionalization, allowing a variety of functional groups to be attached, and producing different types of end-caps. In this work, the effects of end-caps on the atropisomerism, thermally activated polymerization of ortho-imide functional benzoxazines, and the associated properties of polybenzoxazines have been systematically investigated. Several end-caps, with different electronic characteristics and rigidities, were designed. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations were employed to obtain structural information, and differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy were also performed to study the thermally activated polymerization process of benzoxazine monomers. We demonstrated that the atropisomerization can be switched on/off by the manipulation of the steric structure of the end-caps, and polymerization behaviors can be well-controlled by the electronic properties of the end-caps. Moreover, a trade-off effect were found between the thermal properties and the rigidity of the end-caps in polybenzoxazines.

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28

Mino, Takashi, Youichi Tanaka, Youtaro Hattori, Motoko Tanaka, Masami Sakamoto, and Tsutomu Fujita. "Synthesis of N-Aryl Indolines from 2-Fluorobenzaldehyde Dimethylhydrazone Derivatives: Approach to Preparation of C(aryl)-N(Amine) Bond Atropisomeric Amines." Letters in Organic Chemistry 1, no. 1 (January 1, 2004): 67–69. http://dx.doi.org/10.2174/1570178043488699.

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29

Mino, Takashi, Haruka Yamada, Shingo Komatsu, Mizuki Kasai, Masami Sakamoto, and Tsutomu Fujita. "Atropisomerism at C-N Bonds of Acyclic Amines: Synthesis and Application to Palladium-Catalyzed Asymmetric Allylic Alkylations." European Journal of Organic Chemistry 2011, no. 24 (July 12, 2011): 4540–42. http://dx.doi.org/10.1002/ejoc.201100769.

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30

Klvaňa, Robert, Radek Pohl, Jan Pawlas, Jan Čejka, Hana Dvořáková, Richard Hrabal, Stanislav Böhm, Bohumil Kratochvíl, and Josef Kuthan. "Sterically Crowded Heterocycles. XII. Atropisomerism of (1-Aryl-3,5-diphenyl-1H-pyrrol-2-yl)(phenyl)methanones." Collection of Czechoslovak Chemical Communications 65, no. 5 (2000): 651–66. http://dx.doi.org/10.1135/cccc20000651.

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Some 1-(2-substituted phenyl)- and 1-(1-naphthyl)-2,4,6-triphenylpyridinium perchlorates were treated with potassium hexacyano ferrate(III)-potassium hydroxide reagent to give the title pyrroles. Restricted rotation around the C-N bond in the products is demonstrated by NMR experiments with homochiral shift reagents, by semiempirical PM3 calculations as well as using their atropodiastereoselective and enantioselective transformations. Racemisation barriers for the (R)-2-(N-methyl-N-phenylcarbamoyl) derivative were estimated from NMR and polarimetric measurements.

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31

Kwon, Yongseok, and Ahreum Kim. "Catalytic Atroposelective Dynamic Kinetic Resolution of Substituted Indoles." Synlett 33, no. 03 (November 11, 2021): 201–6. http://dx.doi.org/10.1055/a-1694-4695.

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AbstractAdvances in asymmetric catalysis have led to enormous progress in the atroposelective synthesis of axially chiral biaryls. Because of the biological importance of indoles, stereogenic axes in aryl-substituted indoles have attracted considerable research attention in recent years. Here we present a summary of recent advances in the atroposelective synthesis of aryl-substituted indoles by dynamic kinetic resolution. Although several researchers have developed enantioselective syntheses of 3-arylindoles, N-arylindoles have been much less studied. Accordingly, we have developed a Pictet–Spengler reaction with catalytic and enantioselective control of the axial chirality around the C–N bond of the product. A chiral phosphoric acid induces the cyclization smoothly and with high yields and excellent enantioselectivities. To achieve this high selectivity, an NH group at the ortho-position of the N-substituted aromatic ring that interacts favorably with the catalyst is required. Furthermore, when substituted aldehydes are used instead of paraformaldehyde, both point and axial chiralities can be controlled during the cyclization.1 Introduction2 Atropisomerism in Indoles3 Atroposelective Dynamic Kinetic Resolution of 3-Arylindoles4 Atroposelective Dynamic Kinetic Resolution of N-Arylindoles5 Conclusions

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32

Takahashi, Isao, Fumika Morita, Shunsuke Kusagaya, Haruhiko Fukaya, and Osamu Kitagawa. "ChemInform Abstract: Catalytic Enantioselective Synthesis of Atropisomeric 2-Aryl-4-quinolinone Derivatives with an N-C Chiral Axis." ChemInform 44, no. 23 (May 16, 2013): no. http://dx.doi.org/10.1002/chin.201323139.

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33

TAKESHITA, H., A. MORI, Y. IKEDA, and N. KATO. "ChemInform Abstract: C-N Bond Atropisomerism of 1-(2,4-Dimethyl-3-pentyl)cyclohepta(b) pyrrol-2(1H)-one." ChemInform 23, no. 5 (August 22, 2010): no. http://dx.doi.org/10.1002/chin.199205176.

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34

Jwad, Rasha S., Alan H. C. Pang, Luke Hunter, and Roger W. Read. "In Pursuit of Fluorinated Sigma Receptor Ligand Candidates Related to [18F]-FPS." Australian Journal of Chemistry 72, no. 3 (2019): 213. http://dx.doi.org/10.1071/ch18510.

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This paper describes the synthesis of N-arylmethyl(1-benzyl) and N-aroyl(1-benzoyl) 4-(4-fluoromethylphenoxymethyl)piperidines as potential sigma receptor ligands analogous to the potent and highly selective sigma-1 ligand [18F]-FPS, but with enhanced or alternative binding and transport profiles. The synthesis involves N-aroylation of 4-hydroxmethylpiperidine or ethyl nipecotate, functional group manipulation of the ester group or simple activation of the hydroxyl group to introduce the phenoxy component, and subsequent functional group manipulation to reduce the amide group and introduce the fluorine into the fluoromethyl substituent. In its development, the synthesis was found to require early N-aroylation of the piperidine precursor to avoid complications due to anchimeric assistance by its nitrogen in subsequent displacement reactions. New evidence is presented on the pathway followed in a literature report of direct displacement of a benzylic hydroxyl group by fluoride ion under Appel-like conditions. Relevant to the literature report, the halide ion in the fluoromethylphenoxy 1-benzylpiperidine derivatives was surprisingly labile to hydrolytic displacement on chromatography and this aspect is worthy of further study. Moreover, the NMR spectra of the amides were complicated by geometric isomerism about the amide C(O)–N bond, but detailed analysis of spectra from 2-anisoyl derivatives allowed the assignment of diastereomeric contributors to consistent, secondary atropisomerism about the aryl–C(O) bond.

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35

Wezeman, Tim, Yuling Hu, John McMurtrie, Stefan Bräse, and Kye-Simeon Masters. "Synthesis of Non-Symmetrical and Atropisomeric Dibenzo[1,3]diazepines: Pd/CPhos-Catalysed Direct Arylation of Bis-Aryl Aminals." Australian Journal of Chemistry 68, no. 12 (2015): 1859. http://dx.doi.org/10.1071/ch15465.

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Pd/CPhos-catalysis provides direct arylation/cyclisation of methylene-linked bis-anilines to dibenzo[1,3]diazepines v, which are both non-(C2)-symmetrical and axially chiral. Synthesis of the direct arylation substrates commences with substitution of (N-acyl)anilines to methylene methyl sulfide derivatives, followed by halogenation/de-thiomethylation to N-(chloromethyl)anilines. These are substituted with a second aniline derivative, allowing modular preparation of (ortho-halo)aryl-aminal-linked arenes 4. The C–H functionalising direct arylation conditions were adapted from Fagnou and co-workers: substrates and potassium carbonate were heated in dimethylacetamide in the presence of palladium acetate and an electron-rich and sterically hindered biarylphosphine ligand, here CPhos 5. These conditions delivered the C1-(a)symmetric dibenzo[1,3]diazepine targets, which, due to torsion around the axis of the newly formed biaryl bond, are also intrinsically atropisomeric. The axially twisted scaffold is known to impart special properties to ligands/catalysts when the products are further converted into the corresponding seven-membered ring-containing N-heterocyclic carbenes (e.g. xii and xiv).

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36

Takahashi, Masashi, and Osamu Kitagawa. "Catalytic Enantioselective Synthesis of Novel Atropisomeric Compounds having an N-C Chiral Axis and Their Application to Asymmetric Reaction." Journal of Synthetic Organic Chemistry, Japan 69, no. 9 (2011): 985–93. http://dx.doi.org/10.5059/yukigoseikyokaishi.69.985.

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37

Mino, Takashi, Youichi Tanaka, Toshihiro Yabusaki, Daisuke Okumura, Masami Sakamoto, and Tsutomu Fujita. "A C(aryl)N(amine) bond atropisomeric aminophosphine: preparation and use as a ligand in a catalytic asymmetric allylic alkylation." Tetrahedron: Asymmetry 14, no. 17 (September 2003): 2503–6. http://dx.doi.org/10.1016/s0957-4166(03)00545-7.

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38

Takahashi, Masashi, and Osamu Kitagawa. "ChemInform Abstract: Catalytic Enantioselective Synthesis of Novel Atropisomeric Compounds Having an N-C Chiral Axis and Their Application to Asymmetric Reaction." ChemInform 43, no. 7 (January 23, 2012): no. http://dx.doi.org/10.1002/chin.201207241.

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39

Mansour, Anissa, Yassin Belghith, Mohamed Salah Belkhiria, Anna Bujacz, Vincent Guérineau, and Habib Nasri. "Synthesis, crystal structures and spectroscopic characterization of Co(II) bis(4,4′-bipyridine) with meso-porphyrins α,β,α,β-tetrakis(o-pivalamidophenyl) porphyrin (α,β,α,β-TpivPP) and tetraphenylporphyrin (TPP)." Journal of Porphyrins and Phthalocyanines 17, no. 11 (November 2013): 1094–103. http://dx.doi.org/10.1142/s1088424613500843.

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The reaction of the starting materials [ Co II ( Porph )] (Porph = α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrin (TpivPP) and the meso-tetraphenylporphyrin (TPP)) with an excess of 4,4′-bipyridine in chlorobenzene leads to the creation of two cobalt(II) derivatives: [ Co II (α,β,α,β- TpivPP )(4,4′- bpy )2]· C 6 H 5 Cl · C 6 H 14(1) and [ Co II ( TPP )(4,4′- bpy )2]·2 bpy (2). These compounds have been characterized by UV-vis, IR, 1 H NMR and MALDI-TOF spectroscopy. The proton NMR spectra of (1) and (2) clearly indicated that these derivatives are paramagnetic while the UV-vis data confirmed creation of a new six-coordinated or penta-coordinated Co ( II )-meso-porphyrin complexes by displaying red shifted Soret bands. The determined X-ray structures of (1) and (2) show that in the solid state these species are considered as coordination polymers which consist of 1D chains of alternating [ Co II ( Porph )] and 4,4′-bipyridine molecules located at the axial positions of the cobalt(II) coordination sphere. The coordination geometry of Co ( II ) in (1) and (2) is octahedral; the porphyrin (TpivPP or TPP) acts as a tetradentate chelating ligand with four nitrogen atoms from the pyrrole moieties occupying the equatorial positions along the porphyrin core. The N -donor atoms of the 4,4′-bipyridine create the axial ligands. It is noteworthy that for complex (1) the starting porphyrin is the α,α,α,α-TpivPP atropisomer but the final coordination polymer contains the α,β,α,β-TpivPP conformer.

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40

Feng, Jia, and Ren-Rong Liu. "Catalytic Asymmetric Synthesis of N‐N Biaryl Atropisomers." Chemistry – A European Journal, October 18, 2023. http://dx.doi.org/10.1002/chem.202303165.

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Atropisomers featuring a restricted rotational axis have emerged as important structural scaffolds in natural products, drug design, and asymmetric synthesis. Recently, N‐N biaryl atropisomers have drawn increasing interest due to their unique structure and relatively stable axes. However, its asymmetric synthesis remains scarce compared to its well‐developed C‐C biaryl analogs. In this concept, we summarize the asymmetric synthesis of N‐N biaryl atropisomers including N‐N pyrrole‐pyrrole, N‐N pyrroleindole, N‐N indole‐indole, and N‐N indole‐carbazole, during which a series synthetic strategies are highlighted. Also, a synthetic evolution is briefly reviewed and an outlook of N‐N biaryl atropisomers synthesis is offered.

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41

Li, Tong, Linlin Shi, Xinhai Wang, Chen Yang, Dandan Yang, Mao-Ping Song, and Jun-Long Niu. "Cobalt-catalyzed atroposelective C−H activation/annulation to access N−N axially chiral frameworks." Nature Communications 14, no. 1 (August 29, 2023). http://dx.doi.org/10.1038/s41467-023-40978-4.

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AbstractThe N−N atropisomer, as an important and intriguing chiral system, was widely present in natural products, pharmaceutical lead compounds, and advanced material skeletons. The anisotropic structural characteristics caused by its special axial rotation have always been one of the challenges that chemists strive to overcome. Herein, we report an efficient method for the enantioselective synthesis of N−N axially chiral frameworks via a cobalt-catalyzed atroposelective C-H activation/annulation process. The reaction proceeds under mild conditions by using Co(OAc)2·4H2O as the catalyst with a chiral salicyl-oxazoline (Salox) ligand and O2 as an oxidant, affording a variety of N−N axially chiral products with high yields and enantioselectivities. This protocol provides an efficient approach for the facile construction of N−N atropisomers and further expands the range of of N−N axially chiral derivatives. Additionally, under the conditions of electrocatalysis, the desired N−N axially chiral products were also successfully achieved with good to excellent efficiencies and enantioselectivities.

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42

Campbell, Aaron D. G., and Roly J. Armstrong. "Synthetic Strategies to Control C–N Atropisomerism in Acyclic Amines and Amides." Synthesis, February 21, 2023. http://dx.doi.org/10.1055/a-2039-5424.

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Atropisomeric molecules are a privileged class of stereogenic material that have important applications in catalysis, materials science and medicines. To date, the majority of work has been focused upon biaryl and heterobiaryl scaffolds involving restricted rotation between a pair of cyclic fragments, but C–N atropisomeric molecules based upon amines and amides where the nitrogen atom is not part of a ring system are rapidly emerging as an important class of stereogenic molecules. This is the focus of this Short Review article, which begins by discussing the factors which influence the configurational stability of such molecules and provides a historical background to their synthesis. This is followed by a detailed discussion of state-of-the-art catalytic asymmetric strategies that are now available to access C–Nacyclic atropisomers including carboxamides, sulfonamides, sulfinamides, phosphamides and diarylamines. A variety of different synthetic approaches are discussed including kinetic resolution/desymmetrization, amination, C–H functionalization, N-functionalization, and annulation.

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43

Biswas, Subhankar, Subham Kundu, and Subhas Chandra Pan. "Organocatalytic Asymmetric Synthesis of C‐N Atropisomers with Pyrrole, Oxindole and Succinimide Scaffold." Chemistry – An Asian Journal, November 10, 2024. http://dx.doi.org/10.1002/asia.202401132.

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An asymmetric synthesis of C‐N atropisomers with pyrrole, oxindole and succinimide moities was developed via organocatalytic desymmetric Michael addition of 3‐pyrrolyloxindole with prochiral N‐aryl maleimides. The C‐N atropisomers were obtained in acceptable yields with high diastero‐ and enantioselectivities (>20:1 dr, up to >99% ee). C‐N Rotational energy barrier has also been determined.

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44

Zhang, Peng, Jia Feng, and Ren-Rong Liu. "Enantioselective Synthesis of Axially Chiral Benzimidazoles Bearing a C-N axis via Pd-Catalyzed Buchwald–Hartwig Amination." Synlett, April 25, 2022. http://dx.doi.org/10.1055/a-1833-8979.

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Benzimidazole atropisomers bearing a C-N axis are privileged structural frameworks in pharmaceutical and natural products, thus appealing an increasing interest for its asymmetric synthesis. Here, we briefly discuss recent advances in the asymmetric synthesis of benzimidazole atropisomers with a C-N axis, with particular attention to our recently developed palladium-catalyzed intramolecular Buchwald-Hartwig amination strategy.

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45

Zhang, Peng, Jia Feng, and Ren-Rong Liu. "Enantioselective Synthesis of Axially Chiral Benzimidazoles Bearing a C-N axis via Pd-Catalyzed Buchwald–Hartwig Amination." Synlett, April 25, 2022. http://dx.doi.org/10.1055/a-1833-8979.

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Benzimidazole atropisomers bearing a C-N axis are privileged structural frameworks in pharmaceutical and natural products, thus appealing an increasing interest for its asymmetric synthesis. Here, we briefly discuss recent advances in the asymmetric synthesis of benzimidazole atropisomers with a C-N axis, with particular attention to our recently developed palladium-catalyzed intramolecular Buchwald-Hartwig amination strategy.

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46

Rodríguez‐Salamanca, Patricia, Rosario Fernández, Valentín Hornillos, and José M. Lassaletta. "Asymmetric Synthesis of Axially Chiral C−N Atropisomers." Chemistry – A European Journal, March 25, 2022. http://dx.doi.org/10.1002/chem.202104442.

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47

Wu, Chenggui, Ze‐Shui Liu, Yong Shang, Chang Liu, Shuang Deng, Hong‐Gang Cheng, Hengjiang Cong, Yinchun Jiao, and Qianghui Zhou. "Asymmetric Two‐component Alkenyl Catellani Reaction for the Construction of C–N Axial Chirality." Chinese Journal of Chemistry, November 29, 2023. http://dx.doi.org/10.1002/cjoc.202300621.

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Comprehensive SummaryHerein we report an asymmetric two‐component alkenyl Catellani reaction for the construction of C–N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial‐to‐axial chirality transfer process. Various partially aromatic iodinated 2‐pyridones, quinolones, coumarin and uracil substrates react with 2,6‐disubstituted aryl bromides with a tethered amide group, to afford a wide variety of polycyclic C–N atropisomers (38 examples, up to 97% e.e.). The obtained C–N axial chirality is originated from the preformed transient C–C axial chirality with high fidelity. The synthetic utility of this chemistry is demonstrated by facile preparation of complex quinoline and pyridine based C–N atropisomers through a N‐deprotection and aromatization sequence. In addition, a remote axial‐to‐central diastereoinduction process dictated by C–N axial chirality is observed with excellent diastereocontrol.This article is protected by copyright. All rights reserved.

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48

Zhan, Li-Wen, Chuan-Jun Lu, Jia Feng, and Ren-Rong Liu. "Atroposelective Synthesis of C‐N Vinylindole Atropisomers by Palladium‐Catalyzed Asymmetric Hydroarylation of 1‐Alkynylindoles." Angewandte Chemie, September 25, 2023. http://dx.doi.org/10.1002/ange.202312930.

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Transition‐metal‐catalyzed hydroarylation of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity and stereoselectivity. Moreover, the enantioselective hydroarylation of alkynes using organoboron reagents has not been reported. Herein, we report for the first time that palladium compounds can catalyze the hydroarylation of organoborons with 1‐alkynylindoles for the synthesis of chiral C‐N atropisomers. A series of rarely reported vinylindole atropisomers was synthesized with excellent regio‐, stereo‐ (Z‐selectivity), and enantioselectivity under mild reaction conditions. The ready availability of organoborons and alkynes and the simplicity, high stereoselectivity, and good functional group tolerance of this catalytic system make it highly attractive.

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49

Zhan, Li-Wen, Chuan-Jun Lu, Jia Feng, and Ren-Rong Liu. "Atroposelective Synthesis of C‐N Vinylindole Atropisomers by Palladium‐Catalyzed Asymmetric Hydroarylation of 1‐Alkynylindoles." Angewandte Chemie International Edition, September 25, 2023. http://dx.doi.org/10.1002/anie.202312930.

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Transition‐metal‐catalyzed hydroarylation of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity and stereoselectivity. Moreover, the enantioselective hydroarylation of alkynes using organoboron reagents has not been reported. Herein, we report for the first time that palladium compounds can catalyze the hydroarylation of organoborons with 1‐alkynylindoles for the synthesis of chiral C‐N atropisomers. A series of rarely reported vinylindole atropisomers was synthesized with excellent regio‐, stereo‐ (Z‐selectivity), and enantioselectivity under mild reaction conditions. The ready availability of organoborons and alkynes and the simplicity, high stereoselectivity, and good functional group tolerance of this catalytic system make it highly attractive.

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50

Shee, Sayan, Sowmya Shree Ranganathappa, Mahesh S. Gadhave, Romin Gogoi, and Akkattu T. Biju. "Enantioselective Synthesis of C‐O Axially Chiral Diaryl Ethers by NHC‐Catalyzed Atroposelective Desymmetrization." Angewandte Chemie International Edition, November 20, 2023. http://dx.doi.org/10.1002/anie.202311709.

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Axially chiral diaryl ethers, a distinguished class of atropisomers possessing unique dual C‐O axis, hold immense potential for diverse research domains. In contrast to the catalytic enantioselective synthesis of conventional single axis bearing atropisomers, the atroposelective synthesis of axially chiral ethers containing flexible C‐O axis remains a significant challenge. Herein, we demonstrate the first N‐heterocyclic carbene (NHC)‐catalyzed synthesis of axially chiral diaryl ethers via atroposelective esterification of dialdehyde‐containing diaryl ethers. Mechanistically, the reaction proceeds via NHC‐catalyzed desymmetrization strategy to afford the corresponding axially chiral diaryl ether atropisomers in good yields and high enantioselectivities under mild conditions. The derivatization of the synthesized product expands the utility of present strategy via access to a library of C‐O axially chiral compounds. The temperature dependency and preliminary investigations on the racemization barrier of C‐O bonds are also presented.

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