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Arroyo‐Córdoba IJ, Gamboa‐Velázquez G, Avila‐Ortiz CG, Leyva‐Ramírez MA, Cortez‐Picasso MT, García‐Revilla MA, Ramírez‐Ornelas DE, Peña‐Cabrera E, Juaristi E. Structure and Conformation of Novel BODIPY Ugi Adducts. Chemistry 2022; 11:e202200197. [PMID: 36284210 PMCID: PMC9596608 DOI: 10.1002/open.202200197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 09/22/2022] [Indexed: 11/20/2022]
Abstract
Two novel BODIPY‐Ugi (boron dipyrromethene) adducts exhibit peculiar room temperature (T=20 °C) H‐1 NMR spectra in that several protons located at the aromatic aniline‐type ring are lost in the baseline. This observation revealed the existence of a dynamic conformational process where rotation around the C−N bond is hindered. Variable‐temperature H‐1 and C‐13 NMR spectroscopic analysis confirmed this conclusion; that is, low‐temperature spectra show distinct signals for all four aromatic protons below coalescence, whereas average signals are recorded above coalescence (T=+120 °C). Particularly interesting was the rather large difference in chemical shifts for the ortho protons below coalescence, Δδ=1.45 ppm, which was explained based on DFT computational analysis. Indeed, the calculated lowest‐energy gas‐phase conformation of the BODIPY Ugi adducts locates one half of the aniline‐type ring in the shielding anisotropic cone of the bridge phenyl ring in the BODIPY segment. This is in contrast to the solid‐state conformation established by X‐ray diffraction analysis that shows a nearly parallel arrangement of the aromatic rings, probably induced by crystal packing forces.
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Affiliation(s)
- Ismael Javier Arroyo‐Córdoba
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico
| | - Gonzalo Gamboa‐Velázquez
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico
| | - Claudia Gabriela Avila‐Ortiz
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico
| | - Marco A. Leyva‐Ramírez
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico
| | - María Teresa Cortez‐Picasso
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico
| | | | | | - Eduardo Peña‐Cabrera
- Department of ChemistryUniversidad de Guanajuato Noria Alta S/N36050Guanajuato, Gto.Mexico
| | - Eusebio Juaristi
- Department of ChemistryCentro de Investigación y de Estudios AvanzadosAvenida IPN 2508 San Pedro Zacatenco07360Ciudad de MéxicoMexico,El Colegio NacionalLuis González Obregón 23 Centro Histórico06020Ciudad de MéxicoMexico
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Gunal SE, Azizoglu I, Arica O, Haslak ZP, Aviyente V, Dogan I. Solvent dependent hindered rotation versus epimerization in axially chiral thiohydantoin derivatives: an experimental and a computational study. Org Biomol Chem 2022; 20:7622-7631. [PMID: 36111614 DOI: 10.1039/d2ob01025a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
5-Benzyl-3-(o-aryl)-2-thiohydantoin and 5-isobutyl-3-(o-aryl)-2-thiohydantoin derivatives (o-aryl = o-tolyl and o-bromophenyl) have been synthesized by reacting o-aryl isothiocyanates with S-phenylalanine methyl ester hydrochloride or with S-leucine methyl ester hydrochloride in the presence of triethylamine (TEA). The synthesized compounds have a chirality center at C5 of the heterocyclic ring and a chirality axis, the N3-C(aryl) bond. The axially chiral compounds were shown to exist in unequal amounts of SM, SP, RM and RP stereoisomeric forms with a high prevalence of the P isomers over the M isomers. The isomeric assignments were done by comparing the 1H NMR spectra with the HPLC chromatograms. The stereoisomers were resolved micropreparatively by HPLC on chiral stationary phases and the interconversion of the single isomers has been investigated. The conversion type has been determined as epimerization or rotation by the HPLC analyses. It has been found that although the stereoisomers converted to each other only by rotation in toluene, in ethanol epimerization (racemization at C5 of the heteroring) was accompanied with rotation depending on the duration, temperature of the thermal interconversion experiment and the nature of the ortho substituent. The occurrence of epimerization was also proved through H/D exchange reactions via1H NMR experiments done in CD3OD. The rotation and epimerization mechanisms of synthesized compounds were further elucidated by Density Functional Theory (DFT) calculations at M062X/6-311 + G** level of theory and the results were shown to be in harmony with experimental findings.
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Affiliation(s)
- Sule Erol Gunal
- Department of Chemistry, Bogaziçi University, Bebek, Istanbul, Turkey.
| | - Ipek Azizoglu
- Department of Chemistry, Bogaziçi University, Bebek, Istanbul, Turkey.
| | - Oya Arica
- Department of Chemistry, Bogaziçi University, Bebek, Istanbul, Turkey.
| | | | - Viktorya Aviyente
- Department of Chemistry, Bogaziçi University, Bebek, Istanbul, Turkey.
| | - Ilknur Dogan
- Department of Chemistry, Bogaziçi University, Bebek, Istanbul, Turkey.
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3
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Gallegos M, Costales A, Pendás ÁM. Energetic Descriptors of Steric Hindrance in Real Space: An Improved IQA Picture*. Chemphyschem 2021; 22:775-787. [PMID: 33497008 DOI: 10.1002/cphc.202000975] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/05/2021] [Indexed: 11/11/2022]
Abstract
Steric hindrance (SH) plays a central role in the modern chemical narrative, lying at the core of chemical intuition. As it however happens with many successful chemical concepts, SH lacks an underlying physically sound root, and multiple mutually inconsistent approximations have been devised to relate this fuzzy concept to computationally derivable descriptors. We here argue that being SH related to spatial as well as energetic features of interacting systems, SH can be properly handled if we chose a real space energetic stance like the Interacting Quantum Atoms (IQA) approach. Drawing on previous work by Popelier and coworkers (ChemistryOpen 8, 560, 2019) we build an energetic estimator of SH, referred to as EST . We show that the rise in the self-energy of a fragment that accompanies steric congestion is a faithful proxy for the chemist's SH concept if we remove the effect of charge transfer. This can be done rigorously, and the EST here defined provides correct sterics even for hydrogen atoms, where the plain use of deformation energies leads to non-chemical results. The applicability of EST is validated in several chemical scenarios, going from atomic compressions to archetypal SN2 reactions. EST is shown to be a robust steric hindrance descriptor.
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Affiliation(s)
- Miguel Gallegos
- Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain
| | - Aurora Costales
- Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain
| | - Ángel Martín Pendás
- Department of Analytical and Physical Chemistry, University of Oviedo, E-33006, Oviedo, Spain
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Tóth BL, Monory A, Egyed O, Domján A, Bényei A, Szathury B, Novák Z, Stirling A. The ortho effect in directed C-H activation. Chem Sci 2021; 12:5152-5163. [PMID: 34163752 PMCID: PMC8179598 DOI: 10.1039/d1sc00642h] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/20/2021] [Indexed: 12/12/2022] Open
Abstract
The success of transition metal-catalysed ortho-directed C-H activation is often plagued by the effects of undesirable interactions between the directing group (DG) and other groups introduced into the aromatic core of the substrate. In particular, when these groups are in neighbouring positions, their interactions can affect profoundly the efficacy of the C-H activation by transition metals. In this work we introduce a simple substrate-only-based model to interpret the influence of steric hindrance of a group in ortho position to the DG in directed ortho-C-H bond activation reactions, and coined the term Ortho Effect (OE) for such situations. We consider simple descriptors such as torsion angle and torsional energy to predict and explain the reactivity of a given substrate in directed C-H activation reactions. More than 250 examples have been invoked for the model, and the nature of the ortho effect was demonstrated on a wide variety of structures. In order to guide organic chemists, we set structural and energetic criteria to evaluate a priori the efficiency of the metalation step which is usually the rate-determining event in C-H activations, i.e. we provide a simple and general protocol to estimate the reactivity of a potential substrate in C-H activation. For borderline cases these criteria help set the minimum reaction temperature to obtain reasonable reaction rates. As an example for the practical applicability of the model, we performed synthetic validations via palladium-catalysed 2,2,2-trifluoroethylation reactions in our lab. Furthermore, we give predictions for the necessary reaction conditions for several selected DGs.
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Affiliation(s)
- Balázs L Tóth
- ELTE "Lendület" Catalysis and Organic Synthesis Research Group, Faculty of Science, Institute of Chemistry, Eötvös Loránd University Pázmány Péter Sétány. 1/A H-1117 Budapest Hungary
| | - Anna Monory
- ELTE "Lendület" Catalysis and Organic Synthesis Research Group, Faculty of Science, Institute of Chemistry, Eötvös Loránd University Pázmány Péter Sétány. 1/A H-1117 Budapest Hungary
| | - Orsolya Egyed
- Research Centre for Natural Sciences, Eötvös Loránd Research Network Magyar Tudósok Körútja 2 H-1117 Budapest Hungary
| | - Attila Domján
- Research Centre for Natural Sciences, Eötvös Loránd Research Network Magyar Tudósok Körútja 2 H-1117 Budapest Hungary
| | - Attila Bényei
- Department of Physical Chemistry, University of Debrecen Egyetem Tér 1 H-4032 Debrecen Hungary
| | - Bálint Szathury
- Department of Chemistry, University of Cambridge Lensfield Rd Cambridge CB2 1EW UK
| | - Zoltán Novák
- ELTE "Lendület" Catalysis and Organic Synthesis Research Group, Faculty of Science, Institute of Chemistry, Eötvös Loránd University Pázmány Péter Sétány. 1/A H-1117 Budapest Hungary
| | - András Stirling
- Research Centre for Natural Sciences, Eötvös Loránd Research Network Magyar Tudósok Körútja 2 H-1117 Budapest Hungary
- Department of Chemistry, Eszterházy Károly University Leányka u. 6 H-3300 Eger Hungary
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Farran D, Vanthuyne N, Bossa G, Belot V, Albalat M, Jean M, Roussel C. Slight structural modulation around a pivotal bond: high impact on enantiomeric stability. NEW J CHEM 2021. [DOI: 10.1039/d1nj03178c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on an atropisomeric scaffold, structural modifications around chiral axis allowed to establish structure-rotational barrier relationships.
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Affiliation(s)
- Daniel Farran
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Nicolas Vanthuyne
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Giulia Bossa
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Vincent Belot
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Muriel Albalat
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Marion Jean
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
| | - Christian Roussel
- Aix Marseille Univ., CNRS, Centrale Marseille, iSm2, Marseille, France
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Mancinelli M, Bencivenni G, Pecorari D, Mazzanti A. Stereochemistry and Recent Applications of Axially Chiral Organic Molecules. European J Org Chem 2020. [DOI: 10.1002/ejoc.201901918] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Michele Mancinelli
- Department of Industrial Chemistry “Toso Montanari” University of Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Giorgio Bencivenni
- Department of Industrial Chemistry “Toso Montanari” University of Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Daniel Pecorari
- Department of Industrial Chemistry “Toso Montanari” University of Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Andrea Mazzanti
- Department of Industrial Chemistry “Toso Montanari” University of Bologna Viale Risorgimento 4 40136 Bologna Italy
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Mollo MC, Kilimciler NB, Bisceglia JA, Orelli LR. Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol. Beilstein J Org Chem 2020; 16:32-38. [PMID: 31976014 PMCID: PMC6964664 DOI: 10.3762/bjoc.16.5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 12/11/2019] [Indexed: 01/07/2023] Open
Abstract
A general procedure for the synthesis of 2-substituted tetrahydro-1,3-thiazepines by MW-assisted cyclization of 4-thioamidobutanols is presented. The acyclic precursors were prepared in high overall yields by an expeditious three-step diacylation/thionation/deprotection sequence from 4-aminobutanol. Microwave-assisted ring closure of 4-thioamido alcohols promoted by trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of several hitherto unreported seven-membered iminothioethers bearing 2-aryl, alkenyl, aralkyl and alkyl substituents. The cyclodehydration reaction is likely to involve an SN2-type displacement and affords good to excellent yields of the desired heterocycles in very short reaction times.
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Affiliation(s)
- María C Mollo
- Universidad de Buenos Aires. CONICET. Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica. Junín 956, (1113) Buenos Aires, Argentina
| | - Natalia B Kilimciler
- Universidad de Buenos Aires. CONICET. Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica. Junín 956, (1113) Buenos Aires, Argentina
| | - Juan A Bisceglia
- Universidad de Buenos Aires. CONICET. Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica. Junín 956, (1113) Buenos Aires, Argentina
| | - Liliana R Orelli
- Universidad de Buenos Aires. CONICET. Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica. Junín 956, (1113) Buenos Aires, Argentina
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