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Search for "crystallography" in Full Text gives 352 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine
- Piotr Pomarański,
- Piotr Roszkowski,
- Jan K. Maurin,
- Armand Budzianowski and
- Zbigniew Czarnocki
Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214
- spectroscopy and X-ray crystallography (Figure 1) [38]. Surprisingly, the least thermodynamically stable atropisomer syn-syn-3 was isolated as a main product and the proportion of isomers 1:2:3 was ca. 8:42:50. This observation stimulated us to further investigate the mechanism of the palladium cross-coupling
Graphical Abstract
Figure 1: Structures of stereoisomers of 3,4,5-tris(2-methoxyphenyl)-2,6-dimethylpyridines determined by X-ra...
Figure 2: Graphical representation of kinetic, time-dependent 1H NMR analysis of (syn)-7 (100 °C).
Figure 3: Graphical representation of kinetic, time-dependent 1H NMR analysis of (syn)-10 (120 °C).
Figure 4: HT-NMR (300 MHz, DMSO-d6) spectra of A) (syn)-7. B) (syn)-10. Only the upfield (ca. 3.4–4 ppm) regi...
Figure 5: Summary of the results for coupling with ortho-substituted phenylboronic acid for triaryl products.
Figure 6: Summary of results for coupling with ortho-substituted phenylboronic acid for diaryl products.
Figure 7: Proposed intermediates for the 1,2-addition of 5 with methoxy group. A) Oxidative addition step. B)...
Figure 8: Proposed intermediates for the 1,3-addition with methoxy group. A) Oxidative addition step. B) Tran...
Figure 9: Proposed intermediates for the 1,2-addition with chlorine atom. A) Oxidative addition step. B) Tran...
Figure 10: Proposed intermediates for the 1,3-addition with chlorine atom. A) Oxidative addition step. B) Tran...
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
- Hendrik V. Schröder and
- Christoph A. Schalley
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- complexes π-electron-rich aromatic compounds such as dihydroxynaphthalenes or dihydroxybenzenes. The π-donor TTF (1) also forms a 1:1 complex 13 with this host molecule as shown in solution experiments and by crystallography. The complex formation is immediately visible by an emergent green color of these
Graphical Abstract
Figure 1: The two one-electron oxidation reactions of tetrathiafulvalene (TTF, 1) and the corresponding prope...
Figure 2: UV–vis spectra and photographs of TTF 2 in its three stable oxidation states (black line = 2, orang...
Figure 3: Structure and conformations of two TTF dimers in solution, the mixed-valence and the radical-cation...
Figure 4: (a) The isomerism problem of TTF. (b)–(d) Major synthetic breakthroughs for the construction of TTF...
Figure 5: (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their corre...
Figure 6: TTF complexes with different host molecules.
Figure 7: Stable TTF (a) radical-cation and (b) mixed-valence dimers in confined molecular spaces.
Figure 8: A “three-pole supramolecular switch”: Controlled by its oxidation state, TTF (1) jumps back and for...
Figure 9: Redox-controlled closing and opening motion of the artificial molecular lasso 12.
Figure 10: Graphical illustration how a non-degenerate TTF-based shuttle works under electrochemical operation....
Figure 11: The first TTF-based rotaxane 13.
Figure 12: A redox-switchable bistable molecular shuttle 14.
Figure 13: The redox-switchable cyclodextrin-based rotaxane 15.
Figure 14: The redox-switchable non-ionic rotaxane 16 with a pyromellitic diimide macrocycle.
Figure 15: The redox-switchable TTF rotaxane 17 based on a crown/ammonium binding motif.
Figure 16: Structure and operation of the electro- and photochemically switchable rotaxane 18 which acts as po...
Figure 17: (a) The redox-switchable rotaxane 19 with a donor–acceptor pair which is stable in five different s...
Figure 18: Schematic representation of a molecular electronic memory based on a bistable TTF-based rotaxane. (...
Figure 19: Schematic representation of bending motion of a microcantilever beam with gold surface induced by o...
Figure 20: TTF-dimer interactions in a redox-switchable tripodal [4]rotaxane 22.
Figure 21: (a) A molecular friction clutch 23 which can be operated by electrochemical stimuli. (b) Schematic ...
Figure 22: Fusion between rotaxane and catenane: a [3]rotacatenane 24 which can stabilize TTF dimers.
Figure 23: The first TTF-based catenane 25.
Figure 24: Electrochemically controlled circumrotation of the bistable catenane 26.
Figure 25: A tristable switch based on the redox-active [2]catenane 27 with three different stations.
Figure 26: Structure of catenane-functionalized MOF NU-1000 [108] with structural representation of subcomponents. ...
Figure 27: (a) [3]Catenanes 29 and 30 which can stabilize mixed-valence or radical-cation dimers of TTF. (b) S...
Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study
- Ana-Maria Preda,
- Małgorzata Krasowska,
- Lydia Wrobel,
- Philipp Kitschke,
- Phil C. Andrews,
- Jonathan G. MacLellan,
- Lutz Mertens,
- Marcus Korb,
- Tobias Rüffer,
- Heinrich Lang,
- Alexander A. Auer and
- Michael Mehring
Beilstein J. Org. Chem. 2018, 14, 2125–2145, doi:10.3762/bjoc.14.187
- (C6H3-t-Bu2-3,5)2BiCl (5) Colorless single crystals suitable for X-ray crystallography were isolated upon crystallization from a CH2Cl2 solution at ambient temperature (for 4) and at −28 °C (for 5). Compounds 4 and 5·2CH2Cl2 crystallize in the hexagonal space group P63 and orthorhombic space group Pna21
Graphical Abstract
Scheme 1: Triarylbismuth compounds, that serve as examples for the investigation of bismuth···π interactions ...
Figure 1: Ball and stick model of a fragment of a) the zig-zag chain of a 1D arrangement of Ph3Bi (1a). Hydro...
Figure 2: Ball and stick model of a fragment of the zig-zag type arrangement of Ph3Bi (1b) [45], view along the b...
Figure 3: Ball and stick model of Ph3Bi (1c) showing: a) non-centrosymmetric dimers formed via two Bi···π are...
Figure 4: Wire and stick representation of (C6H4-CH═CH2-4)3Bi (2a) showing: a) zig-zag chains of 1D ribbons f...
Figure 5: Wire and stick model of (C6H4-CH═CH2-4)3Bi (2b) showing: a) the formation of 1D ribbons build via t...
Figure 6: Molecular structure of (C6H4-OMe-4)3Bi (3) showing: a) Thermal ellipsoids that are set at 50% proba...
Figure 7: Wire and stick model of (C6H3-t-Bu2-3,5)3Bi (4) showing a 3D network build via four C–Ht-Bu···π (ar...
Figure 8: Wire and stick model of (C6H3-t-Bu2-3,5)2BiCl (5) showing a fragment of the 1D arrangement, view al...
Figure 9: Computed interaction potentials of the distance scan for the idealized BiPh3–benzene complex. E(int...
Figure 10: a) The BiPh3 potential energy curve for idealized interaction structures compared to the interactio...
Figure 11: Structures of studied BiPh3 tetramers extracted from the crystal structure of polymorph 1a. Etetram...
Figure 12: Detailed structures of selected dimers extracted from the crystal structure of polymorph 1a and dis...
Figure 13: Structures of studied BiPh3 tetramers extracted from the crystal structure of polymorph 1b. See Figure 11 fo...
Figure 14: Detailed structures of selected dimers extracted from the crystal structure of polymorph 1b and dis...
Figure 15: Structures of studied BiPh3 tetramers extracted from the crystal structure of polymorph 1c. See Figure 11 fo...
Figure 16: Detailed structures of selected dimers extracted from the crystal structure of the polymorph 1c and...
Figure 17: Distortion energies of monomers (Eprep, blue triangles) and interaction energies of Bi···π and π-st...
D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation
- Michael R. Imrich,
- Jochen Kraft,
- Cäcilia Maichle-Mössmer and
- Thomas Ziegler
Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182
- the α-anomers (11), which were separated by column chromatography. No crystals suitable for X-ray crystallography could be obtained from the direct products of the Ritter reaction. To get a more polar molecule which is more appropriate to form crystals suitable for X-ray crystallography, a deprotected
- reaction mixture [35]. The deprotected oxazoline 10j was isolated in nearly quantitative yield. By covering a saturated solution of 10j in 2-propanol with n-heptane crystals suitable for X-ray crystallography were thus obtained. The compound crystallizes in the orthorhombic space group P212121. The
Graphical Abstract
Figure 1: General structure of PHOX ligands 1 and structures of annulated glucosamine-based PHOX and PyOx lig...
Scheme 1: Preparation of 1,2-isopropylidene-protected D-fructose derivatives with different substitution patt...
Scheme 2: Activation of 7 to oxocarbenium ion 9 in the Ritter reaction.
Scheme 3: Zemplén deacetylation of 10i.
Figure 2: Molecular structure of 10j. Ellipsoids are given at the 50% probability level. Grey = carbon, red =...
Scheme 4: Benzylation of 10j to give 10b.
Scheme 5: Plausible mechanism of the Ritter reaction. For better clarity C-2 is not shown in conformers 9a an...
Scheme 6: Neighboring group participation of ester protective groups. For better clarity C-2 is not shown in ...
Scheme 7: Pd catalyzed Tsuji–Trost reation. BSA: N,O-bis(trimethylsilyl)acetamide, DMM: dimethyl malonate.
Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates
- Vladimir A. Burilov,
- Guzaliya A. Fatikhova,
- Mariya N. Dokuchaeva,
- Ramil I. Nugmanov,
- Diana A. Mironova,
- Pavel V. Dorovatovskii,
- Victor N. Khrustalev,
- Svetlana E. Solovieva and
- Igor S. Antipin
Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173
- gave molecular ion peaks with expulsion of two (in the case of 4) or four (in the case of 8) N2 fragments due to the lability of the azide group upon laser desorption [39]. The spatial structure of the product 8a was established by X-ray crystallography and is presented in Figure 1 including the atomic
Graphical Abstract
Scheme 1: The general structure of triazolylcalix[4]arene derivatives.
Scheme 2: Synthesis of di- (4a,b) and tetraazido (8a,b) calix[4]arene derivatives. Conditions: Ia: AlkBr, K2CO...
Figure 1: Molecular structure of 8a (50% ellipsoids). The dashed line indicates the alternative position of t...
Scheme 3: Synthesis of polyammonium macrocycles 10a,b and 12a,b.
Figure 2: 2D NOESY H1-H1 NMR spectra of 10b in DMSO-d6.
Figure 3: The optical response (OR) of the calixarene/EY systems toward adenosine phosphates. Concentration (...
Figure 4: Supramolecular binding motif of diphosphate (a) and triphosphate (b) groups of nucleotides with the...
Figure 5: UV spectra of EY (1), 10b–EY (2), and 10b–EY in the presence of 0.005 (3), 0.05 (4), 0.5 (5) and 2 ...
Scheme 4: Structure of AEPDA and the corresponding AEPCDA–10b polydiacetylene vesicle.
Figure 6: UV spectra of the AEPCDA polydiacetylene vesicles in the presence of different amounts of 10b; conc...
Figure 7: Photographs of a portion of a 96-well plate containing AEPCDA–10b polydiacetylene vesicles in the a...
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
- Femke Beiroth,
- Tomas Koudelka,
- Thorsten Overath,
- Stefan D. Knight,
- Andreas Tholey and
- Thisbe K. Lindhorst
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- X-ray crystallography, studies in solution add valuable information in molecular recognition studies as they take molecular dynamics as well as solvent effects into consideration. In the latter respect, photoaffinity labeling has evolved as a useful tool for studies under physiological conditions [1
Graphical Abstract
Figure 1: Principle of photoaffinity labeling of proteins with diazirine derivatives. Photolabile ligands are...
Figure 2: FimH crystal structure (pdb code 1KLF) with docked p-nitrophenyl α-D-mannopyranoside (1, pNPMan). F...
Figure 3: Based on the structure of the known FimH ligands 1 and 2, three photolabile α-D-mannosides, 3–5, we...
Figure 4: Connolly representation of photolabile α-D-mannoside 3 in the closed gate (A, PDB code 1UWF) and op...
Scheme 1: Synthesis of photolabile α-D-mannosides 3 and 4. a) H2, Pd-C, methanol, rt, 6 h, 94%; b) HATU, DIPE...
Figure 5: ESIMS spectra of peptide M2 before (A) and after photoreaction (B) with mannoside 3.
Figure 6: Intact protein ESIMS spectra of FimHtr labeling with diazirine derivative 3 with (A) 50% acetonitri...
A hemicryptophane with a triple-stranded helical structure
- Augustin Long,
- Olivier Perraud,
- Erwann Jeanneau,
- Christophe Aronica,
- Jean-Pierre Dutasta and
- Alexandre Martinez
Beilstein J. Org. Chem. 2018, 14, 1885–1889, doi:10.3762/bjoc.14.162
- hemicryptophane 1 bearing both amide and amine functions in its three likers. In solution, the 1H NMR spectrum shows a C3 symmetrical cage, which is also observed in the solid state by X-ray crystallography. Moreover, in the solid, amide and amine functional groups of different linkers interact through hydrogen
Graphical Abstract
Scheme 1: Synthesis of 1.
Figure 1: 1H NMR spectrum of 1 (400 MHz, CDCl3).
Figure 2: X-ray molecular structure of 1. Hydrogen atoms are omitted for clarity; dashed lines represent hydr...
Figure 3: (a) Structure of compound 6. (b) 1H NMR of 6 (CDCl3, 400 MHz). (c) 1H NMR of 1 (CDCl3, 400 MHz).
Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium
- Alphonse Fiebor,
- Richard Tia,
- Banothile C. E. Makhubela and
- Henok H. Kinfe
Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160
- the formation of the corresponding pincer complexes 17c and 17d directly without formation of an isolable bidentate intermediate observed during the synthesis of complexes 17a and 17b. Furthermore, the successful synthesis of the pincer complexes was confirmed by X-ray crystallography and the
Graphical Abstract
Figure 1: Examples of reported SCS palladium(II) pincer complexes 1–13.
Figure 2: a) Reported SNS palladium(II) pincer complexes 14–16 as catalysts for Suzuki–Miyaura cross coupling ...
Scheme 1: Synthesis of pincer ligands 19a–d and complexes 17a–d.
Figure 3: Molecular structure of 17d. Selected bond distances (Å) and bond angles (°); S(1)–Pd(1)–Cl(1) 93.27...
Scheme 2: Proposed mechanism of the Suzuki–Miyaura coupling reaction using pincer complex 17d.
Figure 4: Energy profile for the oxidative addition reaction involving 4-bromoanisole and Pd(II) catalyst pre...
Scheme 3: Investigation on the reusability of the catalyst.
Figure 5: Reusability of pincer complex 17d as a catalyst for the Suzuki–Miyaura cross coupling reaction.
Scheme 4: Suzuki–Miyaura coupling reaction catalysed by the SN-bidentate complex 20a.
Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant
- Irina A. Mironova,
- Pavel S. Postnikov,
- Rosa Y. Yusubova,
- Akira Yoshimura,
- Thomas Wirth,
- Viktor V. Zhdankin,
- Victor N. Nemykin and
- Mekhman S. Yusubov
Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159
- formation of a precipitate consisting of needle-shaped organic crystals and microcrystalline powder of inorganic salts was observed. The needle-shaped organic crystals were manually separated from the inorganic salts and analysed by NMR spectroscopy and X-ray crystallography. 1H and 13C NMR spectra of these
- ) was established by single-crystal X-ray crystallography (for crystallographic details, see Table S1 in Supporting Information File 1). The X-ray structure of an independent unit of IBS-K is shown in Figure 1, and the corresponding structural drawing with interatomic bond distances is presented in
Graphical Abstract
Scheme 1: Previously reported preparation of IBS (1) [17].
Scheme 2: Oxidation of 2-iodobenzenesulfonate 5 by Oxone in water.
Figure 1: X-ray structure of an independent crystal unit of IBS 6-K.
Figure 2: Simplified representation of structure 6-K. Selected interatomic distances (Å): I(1)=O(1) 1.79; I(1...
Scheme 3: Comparison of the oxidation of sodium 2-iodobenzenesulfonate (5) with NaIO4 and 2-iodobenzenesulfon...
First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones
- Grzegorz Mlostoń,
- Katarzyna Urbaniak,
- Paweł Urbaniak,
- Anna Marko,
- Anthony Linden and
- Heinz Heimgartner
Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156
- X-ray crystallography (Figure 1). Remarkably, the presence of OH and Cl substituents in products 4i–l results in a bathochromic shift of UV–vis absorptions. The crystal structure of 4k is that of the regioisomer proposed on the basis of reactivity considerations. Since the space group is
Graphical Abstract
Scheme 1: Reactions of aryl/hetarylthiochalcones 1a–d with 1,4-naphthoquinone (2b).
Scheme 2: Reactions of thiochalcones 1a–d with 1,4-anthraquinones 2c and 2d.
Figure 1: ORTEP plot [29] of the molecular structure of 4k showing the major conformation of the disordered thiop...
Figure 2: Products of the reactions of thiochalcones 1a and 1b with 1,4-benzoquinone (2a) and of 1a with mena...
Synthesis of spirocyclic scaffolds using hypervalent iodine reagents
- Fateh V. Singh,
- Priyanka B. Kole,
- Saeesh R. Mangaonkar and
- Samata E. Shetgaonkar
Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152
- single crystal X-ray crystallography. Dong and co-workers [90] developed a novel way for the synthesis of five membered spiro pyrazolin-5-ones using amide and amine-containing precursors. Herein, five-membered azaheterocyclic derivatives were synthesized efficiently in presence of PIFA and with TFA as an
- groups. The structure of 75 was confirmed by single crystal X-ray crystallography. 3.2. Using hypervalent iodine reagents as catalysts In 2007, Kita and co-workers [98] investigated the first iodoarene-catalyzed spirocyclization of functionalized amides 76 to spirocyclic systems 77 by carbon–nitrogen
Graphical Abstract
Figure 1: The structures of biologically active natural and synthetic products having spirocyclic moiety.
Scheme 1: Iodine(III)-mediated spirocyclization of substituted phenols 7 and 11 to 10 and 13, respectively.
Scheme 2: PIDA-mediated spirolactonization of N-protected tyrosine 14 to spirolactone 16.
Figure 2: The structures of polymer-supported iodine(III) reagents 17a and 17b.
Scheme 3: Spirolactonization of substrates 14 to spirolactones 16 using polymer-supported reagents 17a and 17b...
Scheme 4: PIDA-mediated spirolactonization of 1-(p-hydroxyaryl)cyclobutanols 18 to spirolactones 19.
Scheme 5: Iodine(III)-mediated spirocyclization of aryl alkynes 24 to spirolactones 26 by the reaction with b...
Scheme 6: Bridged iodine(III)-mediated spirocyclization of phenols 27 to spirodienones 29.
Scheme 7: Iodine(III)-mediated spirocyclization of arnottin I (30) to its spirocyclic analogue arnottin II (32...
Scheme 8: Iodine(III)-catalyzed spirolactonization of p-substituted phenols 27 to spirolactones 29 using iodo...
Scheme 9: Iodine(III)-catalyzed oxylactonization of ketocarboxylic acid 34 to spirolactone 36 using iodobenze...
Scheme 10: Iodine(III)-mediated asymmetric oxidative spirocyclization of naphthyl acids 37 to naphthyl spirola...
Scheme 11: Oxidative cyclization of L-tyrosine 14 to spirocyclic lactone 16 using PIDA (15).
Scheme 12: Oxidative cyclization of oxazoline derivatives 41 to spirolactams 42 using PIDA (15).
Scheme 13: Oxidative cyclization of oxazoline 43 to spirolactam 44 using PIDA 15 as oxidant.
Scheme 14: PIFA-mediated spirocyclization of amides 46 to N-spirolactams 47 using PIFA (31) as an electrophile....
Scheme 15: Synthesis of spirolactam 49 from phenolic enamide 48 using PIDA (15).
Scheme 16: Iodine(III)-mediated spirocyclization of alkyl hydroxamates 50 to spirolactams 51 using stoichiomet...
Scheme 17: PIFA-mediated cyclization of substrate 52 to spirocyclic product 54.
Scheme 18: Synthesis of spiro β-lactams 56 by oxidative coupling reaction of p-substituted phenols 55 using PI...
Scheme 19: Iodine(III)-mediated spirocyclization of para-substituted amide 58 to spirolactam 59 by the reactio...
Scheme 20: Iodine(III)-mediated synthesis of spirolactams 61 from anilide derivatives 60.
Scheme 21: PIFA-mediated oxidative cyclization of anilide 60 to bis-spirobisoxindole 61.
Scheme 22: PIDA-mediated spirocyclization of phenylacetamides 65 to spirocyclic lactams 66.
Scheme 23: Oxidative dearomatization of arylamines 67 with PIFA (31) to give dieniminium salts 68.
Scheme 24: PIFA-mediated oxidative spirocarbocyclization of 4-methoxybenzamide 69 with diphenylacetylene (70) ...
Scheme 25: Synthesis of spiroxyindole 75 using I2O5/TBHP oxidative system.
Scheme 26: Iodine(III)-catalyzed spirolactonization of functionalized amides 76 to spirolactones 77 using iodo...
Scheme 27: Intramolecular cyclization of alkenes 78 to spirolactams 80 using Pd(II) 79 and PIDA (15) as the ox...
Scheme 28: Iodine(III)-catalyzed spiroaminocyclization of amides 76 to spirolactam 77 using bis(iodoarene) 81 ...
Scheme 29: Iodine(III)-catalyzed spirolactonization of N-phenyl benzamides 82 to spirolactams 83 using iodoben...
Scheme 30: Iodine(III)-mediated asymmetric oxidative spirocyclization of phenols 84 to spirolactams 86 using c...
Scheme 31: Iodine(III)-catalyzed asymmetric oxidative spirocyclization of N-aryl naphthamides 87 to spirocycli...
Scheme 32: Cyclization of p-substituted phenolic compound 89 to spirolactam 90 using PIDA (15) in TFE.
Scheme 33: Iodine(III)-mediated synthesis of spirocyclic compound 93 from substrates 92 using PIDA (15) as an ...
Scheme 34: Iodine(III)-mediated spirocyclization of p-substituted phenol 48 to spirocyclic compound 49 using P...
Scheme 35: Bridged iodine(III)-mediated spirocyclization of O-silylated phenolic compound 96 in the synthesis ...
Scheme 36: PIFA-mediated approach for the spirocyclization of ortho-substituted phenols 98 to aza-spirocarbocy...
Scheme 37: Oxidative cyclization of para-substituted phenols 102 to spirocarbocyclic compounds 104 using Koser...
Scheme 38: Iodine(III)-mediated spirocyclization of aryl alkynes 105 to spirocarbocyclic compound 106 by the r...
Scheme 39: Iodine(III)-mediated spirocarbocyclization of ortho-substituted phenols 107 to spirocarbocyclic com...
Scheme 40: PIFA-mediated oxidative cyclization of substrates 110 to spirocarbocyclic compounds 111.
Scheme 41: Iodine(III)-mediated cyclization of substrate 113 to spirocyclic compound 114.
Scheme 42: Iodine(III)-mediated spirocyclization of phenolic substrate 116 to the spirocarbocyclic natural pro...
Scheme 43: Iodine(III)-catalyzed spirocyclization of phenols 117 to spirocarbocyclic products 119 using iodoar...
Scheme 44: PIFA-mediated spirocyclization of 110 to spirocyclic compound 111 using PIFA (31) as electrophile.
Scheme 45: PIDA-mediated spirocyclization of phenolic sulfonamide 122 to spiroketones 123.
Scheme 46: Iodine(III)-mediated oxidative spirocyclization of 2-naphthol derivatives 124 to spiropyrrolidines ...
Scheme 47: PIDA-mediated oxidative spirocyclization of m-substituted phenols 126 to tricyclic spiroketals 127.
Figure 3: The structures of chiral organoiodine(III) catalysts 129a and 129b.
Scheme 48: Iodine(III)-catalyzed oxidative spirocyclization of substituted phenols 128 to spirocyclic ketals 1...
Scheme 49: Oxidative spirocyclization of para-substituted phenol 131 to spirodienone 133 using polymer support...
Scheme 50: Oxidative cyclization of bis-hydroxynaphthyl ether 135 to spiroketal 136 using PIDA (15) as an elec...
Scheme 51: Oxidative spirocyclization of phenolic compound 139 to spirodienone 140 using polymer-supported PID...
Scheme 52: PIFA-mediated oxidative cyclization of catechol derived substrate 142 to spirocyclic product 143.
Scheme 53: Oxidative spirocyclization of p-substituted phenolic substrate 145 to aculeatin A (146a) and aculea...
Scheme 54: Oxidative spirocyclization of p-substituted phenolic substrate 147 to aculeatin A (146a) and aculea...
Scheme 55: Oxidative spirocyclization of p-substituted phenolic substrate 148 to aculeatin D (149) using elect...
Scheme 56: Cyclization of phenolic substrate 131 to spirocyclic product 133 using polymer-supported PIFA 150.
Scheme 57: Iodine(III)-mediated oxidative intermolecular spirocyclization of 7-methoxy-α-naphthol (152) to spi...
Scheme 58: Oxidative cyclization of phenols 155 to spiro-ketals 156 using electrophilic species PIDA (15).
Scheme 59: Iodine(III)-catalyzed oxidative spirocyclization of ortho-substituted phenols 158 to spirocyclic ke...
Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies
- Rakesh Puttreddy,
- Ngong Kodiah Beyeh,
- S. Maryamdokht Taimoory,
- Daniel Meister,
- John F. Trant and
- Kari Rissanen
Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146
- Discussion Solid-state X-ray crystallography Nine X-ray crystal structures were obtained from BrC6 in combination with twelve PyNO guest molecules. Several attempts to obtain single crystals of BrC6 by itself, 1+BrC6, 2+BrC6 and 9+BrC6 in methanol were unsuccessful. In the following discussions, for example
- crystallography and 1H NMR solution studies in three different hydrogen-bond-competitive solvents. In the solid state, BrC6 undergoes large cavity conformational changes to accommodate the N-oxide guests compared to our previously studied host systems, C-ethyl-2-bromoresorcinarene and C-propyl-2
- calculated energies of these bonds, E(x) (kcal/mol), proposed by Espinosa et al. [53][54]. Summary of endo/exo host–guest complexations studied in solution by 1H NMR in comparison to the solid state by single crystal X-ray crystallography. Supporting Information Supporting Information File 222: Experimental
Graphical Abstract
Figure 1: The chemical structures of C-ethyl-2-bromoresorcinarene (BrC2), C-propyl-2-bromoresorcinarene (BrC3...
Figure 2: X-ray crystal structures of (a) 3@BrC6, (b) 4@BrC6, (c) 5@BrC6, (d) 6@BrC6, (e) 7@BrC6, (f) 8@BrC6,...
Figure 3: Comparison of X-ray crystal structures (a) 3@BrC2, (c) 3@BrC3, and (e) 3@BrC6 and their DFT-based o...
Figure 4: (a) The negative potential localised on the N-oxide oxygen in 3@BrC6 and, (b) the positive charge d...
Figure 5: An expansion of the 1H NMR (6.6 mM at 298 K, 500 MHz) of BrC6 complexes with 3. Spectra are produce...
A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene
- Liu-Pan Yang,
- Song-Bo Lu,
- Arto Valkonen,
- Fangfang Pan,
- Kari Rissanen and
- Wei Jiang
Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134
- IV and III, respectively, to achieve optimal binding [37]. This has been unambiguously confirmed by X-ray single crystallography (Figure 1b and 1c). Guest 10+ is a strong binder and its induction on the conformations of ZB4 was further analyzed. The guest exchange in solution of 10+@ZB4 is fast
- 14+@ZB4-III, 16+@ZB4-III, 18+@ZB4-III, and 21+@ZB4-III suitable for X-ray single crystallography, were obtained and their crystal structures are shown in Figure 3. The substituents of these four guests located at three representative positions in Figure 2. Therefore, a closer look at their crystal
- recognition of ZB4 using NMR, ITC titration and X-ray crystallography. Similar to TA4, ZB4 is able to host a wide range of organic cations. However, in contrast to TA4, ZB4 shows no large amplitude of conformational response to the electronic nature of substituents on the guests, and its binding affinities
Graphical Abstract
Scheme 1: (a) Chemical structures of ZB4 and the guests involved in this research. The counterions are PF6−. ...
Figure 1: X-ray single crystal structure of ZB4 and the host–guest complexes. a) ZB4, b) 2+@ZB4-IV, c) 3+@ZB4...
Figure 2: Parabolic free-energy relationship between log(KR/KH) and Hammett parameter σp. KR: guests 11+–21+; ...
Figure 3: X-ray single crystal structures of 14+@ZB4-III, 16+@ZB4-III, 18+@ZB4-III and 21+@ZB4-III. Butyl gro...
Figure 4: X-ray single crystal structures of 18+@ZB4-III and 18+ in 18+@ZB4-III.
Figure 5: Linear relationships of ΔH with temperature (left, slope = −0.13, R2 = 0.9956) and TΔS (right, slop...
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
An overview of recent advances in duplex DNA recognition by small molecules
- Sayantan Bhaduri,
- Nihar Ranjan and
- Dev P. Arya
Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93
- surface plasmon resonance, X-ray crystallography and molecular modeling [130]. These experiments revealed that these novel conjugates form 1:1 complexes
Graphical Abstract
Figure 1: A figure showing the hydrogen bonding patterns observed in (a) duplex (b) triplex and (c) quadruple...
Figure 2: (a) Portions of MATα1–MATα2 are shown contacting the minor groove of the DNA substrate. Key arginin...
Figure 3: Chemical structures of naturally occurring and synthetic hybrid minor groove binders.
Figure 4: Synthetic structural analogs of distamycin A by replacing one or more pyrrole rings with other hete...
Figure 5: Pictorial representation of the binding model of pyrrole–imidazole (Py/Im) polyamides based on the ...
Figure 6: Chemical structures of synthetic “hairpin” pyrrole–imidazole (Py/Im) conjugates.
Figure 7: (a) Minor groove complex formation between DNA duplex and 8-ring cyclic Py/Im polyamide (conjugate ...
Figure 8: Telomere-targeting tandem hairpin Py/Im polyamides 23 and 24 capable of recognizing >10 base pairs; ...
Figure 9: Representative examples of recently developed DNA minor groove binders.
Figure 10: Chemical structures of bisbenzamidazoles Hoechst 33258 and 33342 and their synthetic structural ana...
Figure 11: Chemical structures of bisamidines such as diminazene, DAPI, pentamidine and their synthetic struct...
Figure 12: Representative examples of recently developed bisamidine derivatives.
Figure 13: Chemical structures of chromomycin, mithramycin and their synthetic structural analogs 91 and 92.
Figure 14: Chemical structures of well-known naturally occurring DNA binding intercalators.
Figure 15: Naturally occurring indolocarbazole rebeccamycin and its synthetic analogs.
Figure 16: Representative examples of naturally occurring and synthetic derivatives of DNA intercalating agent...
Figure 17: Several recent synthetic varieties of DNA intercalators.
Figure 18: Aminoglycoside (neomycin)–Hoechst 33258/intercalator conjugates.
Figure 19: Chemical structures of triazole linked neomycin dimers and neomycin–bisbenzimidazole conjugates.
Figure 20: Representative examples of naturally occurring and synthetic analogs of DNA binding alkylating agen...
Figure 21: Chemical structures of naturally occurring and synthetic analogs of pyrrolobenzodiazepines.
Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle
- Akira Yoshimura,
- Michael T. Shea,
- Cody L. Makitalo,
- Melissa E. Jarvi,
- Gregory T. Rohde,
- Akio Saito,
- Mekhman S. Yusubov and
- Viktor V. Zhdankin
Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87
- oxidation of 2-iodo-N,N’-diisopropylisophthalamide with m-chloroperoxybenzoic acid under mild conditions. Single crystal X-ray crystallography of this compound revealed a five-membered bis-heterocyclic structure with two covalent bonds between the iodine atom and the nitrogen atoms. This novel benziodazole
- and peptides [23][24][25]. Numerous examples of five-membered hypervalent iodine(III) heterocycles containing other than oxygen heteroatoms, such as sulfur [26], boron [27][28], phosphorous [29], or nitrogen [30][31][32], have been synthesized and characterized by X-ray crystallography. In particular
- refrigerator for several weeks. Solutions of 7a in CDCl3 or CD3CN did not show any decomposition even after storage for over one month at room temperature. The solid state structure of compound 7a was characterized by X-ray crystallography. A single crystal X-ray diffraction of 7a confirmed the bicyclic
Graphical Abstract
Scheme 1: Representative examples of benziodoxoles and benziodazoles.
Scheme 2: Preparation of bicyclic benziodazole 7a.
Figure 1: X-ray crystal structure of compound 7a. Ellipsoids are drawn to the 50% probability level. Selected...
Scheme 3: Benziodadiazole 7a mediated oxidatively assisted esterification and amidation reactions.
Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies
- Elias Christoforides,
- Andreas Papaioannou and
- Kostas Bethanis
Beilstein J. Org. Chem. 2018, 14, 838–848, doi:10.3762/bjoc.14.69
- characterization of the cholesterol/β-CD inclusion complex [22], its binding affinity [23][24][25], the inclusion mode of the complex [26] and its dynamic behavior through MD simulations [27][28][29] but its crystal structure is absent. In this work, the structure of CHL/β-CD is determined by X-ray crystallography
- dimers [24][25][33]. In this study, the determination by X-ray crystallography of the CHL inclusion in a head–head β-CD dimer conclusively resolves this ambiguity. The binding affinity calculations based on this model give high absolute ΔG values at both 300 K and 340 K temperatures (Table 2) indicating
- the slow cooling crystallization technique. More specific, 10.22 mg (0.026 mmoles) of CHL were added in a 2 mL equimolar aqueous solution of β-CD. The mixture was stirred at 70 °C for 4 h and gradually cooled to room temperature over a period of seven days. X-ray crystallography A prismatic colorless
Graphical Abstract
Figure 1: Schematic representation of (a) the cholesterol molecule; (b) the β-cyclodextrin molecule.
Figure 2: (a) Crystal structure of the inclusion compound of cholesterol in β-CD dimer. Water molecules are o...
Figure 3: RMSD over time for all CHL (green) and β-CD (blue) atoms (a) at 300 K and (b) at 340 K.
Figure 4: Representative snapshots of the CHL/β-CD inclusion complex at 0 (a, c) and 11 ns (b, d) in timescal...
Figure 5: (a) Distance between the O1 atom (CHL) and the centroid DK of the O4n atoms of host A at 300 (green...
Phosphodiester models for cleavage of nucleic acids
- Satu Mikkola,
- Tuomas Lönnberg and
- Harri Lönnberg
Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68
- of nucleases by pH-rate dependency, X-ray crystallography, amino acid/nucleotide substitution and computational approaches, experimental and theoretical studies with small molecular model compounds still play a role. With small molecules, the importance of various elementary processes, such as proton
Graphical Abstract
Figure 1: Enzymatic cleavage of phosphodiester linkages of DNA and RNA.
Figure 2: Energy profiles for a concerted ANDN (A) and stepwise mechanisms (AN + DN) with rate-limiting break...
Figure 3: Pseudorotation of a trigonal bipyramidal phosphorane intermediate by Berry pseudorotation [20].
Figure 4: Protolytic equilibria of phosphorane intermediate of RNA transesterification.
Figure 5: Structures of acyclic analogs of ribonucleosides.
Figure 6: First-order rate constants for buffer-independent partial reactions of uridyl-3´,5´-uridine at pH 5...
Scheme 1: pH- and buffer-independent cleavage and isomerization of RNA phosphodiester linkages. Observed firs...
Scheme 2: Mechanism for the pH- and buffer-independent cleavage of RNA phosphodiester linkages.
Scheme 3: Hydroxide-ion-catalyzed cleavage of RNA phosphodiester linkages.
Scheme 4: Anslyn's and Breslow's mechanism for the buffer-catalyzed cleavage and isomerization of RNA phospho...
Scheme 5: General base-catalyzed cleavage of RNA phosphodiester bonds.
Scheme 6: Kirby´s mechanism for the buffer-catalyzed cleavage of RNA phosphodiester bonds [65].
Figure 7: Guanidinium-group-based cleaving agents of RNA.
Scheme 7: Tautomers of triazine-based cleaving agents and cleavage of RNA phosphodiester bonds by these agent...
Figure 8: Bifunctional guanidine/guanidinium group-based cleaving agents of RNA.
Scheme 8: Cleavage of HPNP by 1,3-distal calix[4]arene bearing two guanidine groups [80].
Figure 9: Cyclic amine-based cleaving agents of RNA.
Scheme 9: Mechanism for the pH-independent cleavage and isomerization of model compound 12a in the pH-range 7...
Scheme 10: Mechanism for the pH-independent cleavage of guanylyl-3´,3´-(2´-amino-2´-deoxyuridine) at pH 6-8 [89].
Scheme 11: Cleavage of uridine 3´-dimethyl phosphate by A) intermolecular attack of methoxide ion and B) intra...
Scheme 12: Transesterification of group I introns and hydrolysis of phosphotriester models proceed through a s...
Scheme 13: Cleavage of trinucleoside 3´,3´,5´-monophosphates by A) P–O3´ and B) P–O5´ bond fission.
Figure 10: Model compounds (23–25) and metal ion binding ligands used in kinetic studies of metal-ion-promoted...
Figure 11: Zn2+-ion-based mono- and di-nuclear cleaving agents of nucleic acids.
Figure 12: Miscellaneous complexes and ligands used in kinetic studies of metal-ion-promoted cleavage of nucle...
Figure 13: Azacrown ligands 34 and 35 and dinuclear Zn2+ complex 36 used in kinetic studies of metal-ion-promo...
Figure 14: Metal ion complexes used for determination of βlg values of metal-ion-promoted cleavage of RNA mode...
Figure 15: Metal ion complexes used in kinetic studies of medium effects on the cleavage of RNA model compound...
Scheme 14: Alternative mechanisms for metal-ion-promoted cleavage of phosphodiesters.
Figure 16: Nucleic acid cleaving agents where the attacking oxyanion is not coordinated to metal ion.
Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands
- Rebecca Pittkowski and
- Thomas Strassner
Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54
- laboratory of the department using a Eurovektor Hekatech EA-3000 elemental analyzer. Melting points were measured on a Wagner and Munz Poly Therm A system and are not corrected. X-ray crystallography Crystallographic data for compound 3 were collected on Bruker D8 VENTURE Kappa Duo PHOTON200 by IμS micro
Graphical Abstract
Scheme 1: Synthesis of complexes 2 and 3.
Figure 1: ORTEP representation of 3. Thermal ellipsoids are drawn at the 50% probability level. Selected bond...
Figure 2: UV–vis absorption spectra of complexes 2 and 3 measured in dichloromethane at room temperature.
Figure 3: Emission spectra of complexes 2 and 3 measured at room temperature and 77 K, 2 wt % in a PMMA matri...
Figure 4: Cyclic voltammograms of complexes 2 and 3, analyte concentration 10−4 M. Measured in DMF (0.1 M TBA...
Figure 5: Thin films of Pt(MPIM)(acac) left, Pt(MPIM)(mes) (2) middle, and Pt(MPIM)(dur) (3) right, 2 wt % in...
Figure 6: Photoluminescence spectra of 2 and 3 compared to the emission profile of Pt(MPIM)(acac), 2 wt % in ...
Figure 7: Localization of spin density on the complexes Pt(MPIM)(acac) left, Pt(MPIM)(mes) (2) middle, and Pt...
An air-stable bisboron complex: a practical bidentate Lewis acid catalyst
- Longcheng Hong,
- Sebastian Ahles,
- Andreas H. Heindl,
- Gastelle Tiétcha,
- Andrey Petrov,
- Zhenpin Lu,
- Christian Logemann and
- Hermann A. Wegner
Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48
- experimental procedures, copies of 1H and 13C NMR spectra, UV–vis spectra as well as the X-ray crystallography. Supporting Information File 32: CIF of bisborane complex B. Acknowledgements Funding by the BMEL (Federal Ministry of Food and Agriculture) within the project FOREST (22403116) and by the CMBlu AG
Graphical Abstract
Scheme 1: Bidentate bisborane Lewis acids.
Scheme 2: Complexation reaction of 5,10-dimethyl-5,10-dihydroboranthrene (A) with Lewis bases analyzed by NMR...
Figure 1: Time-dependent 1H NMR spectra of the air-exposed complex B.
Scheme 3: Synthetic procedures of bisboranes A and B.
Figure 2: ORTEP drawing (50% probability) of complex B.
Figure 3: UV–vis spectrum of complex B was measured in CHCl3 and compared with pyridazine and bisborane A (co...
Enzyme-free genetic copying of DNA and RNA sequences
- Marilyne Sosson and
- Clemens Richert
Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47
- aminoimidazolides as monomers [52]; b) one of the structural arrangements found in a recent crystallography study that used oligophosphates as model compounds [53]. Proposed steps of enzyme-free primer extension with in situ activation, using the "general condensation buffer" containing EDC and 1-ethylimidazole as
Graphical Abstract
Figure 1: Enzyme-free template-directed extension of an RNA primer by one nucleotide. B = nucleobase, LG = le...
Figure 2: Oligomerization of the 2-methylimidazolide of guanosine-5'-monophosphate on a poly(C) template.
Figure 3: Structures of backbone linkages produced in enzyme-free primer extension reactions: the phosphorami...
Figure 4: System used for studying the template effect with all 64 possible triplets at the extension site (B...
Figure 5: Interactions attracting the incoming nucleotide to the extension site. Besides base pairing via hyd...
Figure 6: Three possible fates of activated nucleotides in aqueous buffer that result from hydrolysis, primer...
Figure 7: Steps and equilibria considered in our quantitative model of chemical primer extension [34]. The model ...
Figure 8: Binding equilibrium between mononucleotides and hairpins representing primer–template duplexes, as ...
Figure 9: Template-directed primer extension on an RNA template performed with OAt-GMP at 1.8 mM (orange), 3....
Figure 10: Copying of four nucleotides on an immobilized RNA duplex, as reported by Deck et al. [32].
Figure 11: Extension cycle of aminoterminal primer with N-protected nucleotides on solid support, as described...
Figure 12: Formation of a highly reactive methylimidazolium bisphosphate from methylimidazolides of nucleotide...
Figure 13: 31P NMR spectrum (161.9 MHz) of crude MeIm-GMP in D2O. The resonance of the imidazolium bisphosphat...
Figure 14: Imidazolium bisphosphate as intermediate in the primer extension reaction, as described by Szostak ...
Figure 15: Proposed steps of enzyme-free primer extension with in situ activation, using the "general condensa...
5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines
- Ranjana Aggarwal and
- Suresh Kumar
Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15
- ] starting from 7-diethylaminocoumarin-3-aldehyde (26) and 5-aminopyrazole derivatives 16 (Scheme 4). The structure of the synthesized compounds was confirmed by X-ray crystallography, 1H and 13C NMR and HRMS studies. The relationships between the structures and chemical properties of these compounds were
Graphical Abstract
Figure 1: Selected examples of drugs with fused pyrazole rings.
Figure 2: Typical structures of some fused pyrazoloazines from 5-aminopyrazoles.
Scheme 1: Regiospecific synthesis of 4 and 6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridines.
Scheme 2: Synthesis of pyrazolo[3,4-b]pyridine-6-carboxylates.
Scheme 3: Synthesis of 1,4,6-triaryl-1H-pyrazolo[3,4-b]pyridines with ionic liquid .
Scheme 4: Synthesis of coumarin-based isomeric tetracyclic pyrazolo[3,4-b]pyridines.
Scheme 5: Synthesis of 6-substituted pyrazolo[3,4-b]pyridines under Heck conditions.
Scheme 6: Microwave-assisted palladium-catalyzed synthesis of pyrazolo[3,4-b]pyridines.
Scheme 7: Acid-catalyzed synthesis of pyrazolo[3,4-b]pyridines via enaminones.
Scheme 8: Synthesis of pyrazolo[3,4-b]pyridines via aza-Diels–Alder reaction.
Scheme 9: Synthesis of macrocyclane fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 10: Three-component synthesis of 4,7-dihydro-1H-pyrazolo[3,4-b]pyridine derivatives.
Scheme 11: Ultrasonicated synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2,6'(1'H)-diones.
Scheme 12: Synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine] derivatives under conventional heating co...
Scheme 13: Nanoparticle-catalyzed synthesis of pyrazolo[3,4-b]pyridine-spiroindolinones.
Scheme 14: Microwave-assisted multicomponent synthesis of spiropyrazolo[3,4-b]pyridines.
Scheme 15: Unexpected synthesis of naphthoic acid-substituted pyrazolo[3,4-b]pyridines.
Scheme 16: Multicomponent synthesis of variously substituted pyrazolo[3,4-b]pyridine derivatives.
Scheme 17: Three-component synthesis of 4,7-dihydropyrazolo[3,4-b]pyridines and pyrazolo[3,4-b]pyridines.
Scheme 18: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanediones.
Scheme 19: Ultrasound-mediated three-component synthesis of pyrazolo[3,4-b]pyridines.
Scheme 20: Multicomponent synthesis of 4-aryl-3-methyl-1-phenyl-4,6,8,9-tetrahydropyrazolo [3,4-b]thiopyrano[4...
Scheme 21: Synthesis of 2,3-dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones.
Scheme 22: FeCl3-catalyzed synthesis of o-hydroxyphenylpyrazolo[3,4-b]pyridine derivatives.
Scheme 23: Ionic liquid-mediated synthesis of pyrazolo[3,4-b]pyridines.
Scheme 24: Microwave-assisted synthesis of pyrazolo[3,4-b]pyridines.
Scheme 25: Multicomponent synthesis of pyrazolo[3,4-b]pyridine-5-carbonitriles.
Scheme 26: Unusual domino synthesis of 4,7-dihydropyrazolo[3,4-b]pyridine-5-nitriles.
Scheme 27: Synthesis of 4,5,6,7-tetrahydro-4H-pyrazolo[3,4-b]pyridines under conventional heating and ultrasou...
Scheme 28: L-Proline-catalyzed synthesis of of pyrazolo[3,4-b]pyridine.
Scheme 29: Microwave-assisted synthesis of 5-aminoarylpyrazolo[3,4-b]pyridines.
Scheme 30: Microwave-assisted multi-component synthesis of pyrazolo[3,4-e]indolizines.
Scheme 31: Synthesis of fluoropropynyl and fluoroalkyl substituted pyrazolo[1,5-a]pyrimidine.
Scheme 32: Acid-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine derivatives.
Scheme 33: Chemoselective and regiospecific synthesis of 2-(3-methylpyrazol-1’-yl)-5-methylpyrazolo[1,5-a]pyri...
Scheme 34: Regioselective synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 35: Microwave-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidine carboxylates.
Scheme 36: Microwave and ultrasound-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 37: Base-catalyzed unprecedented synthesis of pyrazolo[1,5-a]pyrimidines via C–C bond cleavage.
Scheme 38: Synthesis of aminobenzothiazole/piperazine linked pyrazolo[1,5-a]pyrimidines.
Scheme 39: Synthesis of aminoalkylpyrazolo[1,5-a]pyrimidine-7-amines.
Scheme 40: Synthesis of pyrazolo[1,5-a]pyrimidines from condensation of 5-aminopyrazole 126 and ethyl acetoace...
Scheme 41: Synthesis of 7-aminopyrazolo[1,5-a]pyrimidines.
Scheme 42: Unexpected synthesis of 7-aminopyrazolo[1,5-a]pyrimidines under solvent free and solvent-mediated c...
Scheme 43: Synthesis of N-(4-aminophenyl)-7-aryloxypyrazolo[1,5-a]pyrimidin-5-amines.
Scheme 44: Base-catalyzed synthesis of 5,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 45: Synthesis of 6,7-dihydropyrazolo[1,5-a]pyrimidines in PEG-400.
Scheme 46: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides.
Scheme 47: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine derivatives under conventional heating and micro...
Scheme 48: Synthesis of N-aroylpyrazolo[1,5-a]pyrimidine-5-amines.
Scheme 49: Regioselective synthesis of ethyl pyrazolo[1,5-a]pyrimidine-7-carboxylate.
Scheme 50: Sodium methoxide-catalyzed synthesis of 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 51: Synthesis of various pyrazolo[3,4-d]pyrimidine derivatives.
Scheme 52: Synthesis of hydrazinopyrazolo[3,4-d]pyrimidine derivatives.
Scheme 53: Synthesis of N-arylidinepyrazolo[3,4-d]pyrimidin-5-amines.
Scheme 54: Synthesis of pyrazolo[3,4-d]pyrimidinyl-4-amines.
Scheme 55: Iodine-catalyzed synthesis of pyrazolo[3,4-d]pyrimidinones.
Scheme 56: Synthesis of ethyl 6-amino-2H-pyrazolo[3,4-d]pyrimidine-4-carboxylate.
Scheme 57: Synthesis of 4-substituted-(3,6-dihydropyran-4-yl)-1H-pyrazolo[3,4-d]pyrimidines.
Scheme 58: Synthesis of 1-(2,4-dichlorophenyl)pyrazolo[3,4-d]pyrimidin-4-yl carboxamides.
Scheme 59: Synthesis of 5-(1,3,4-thidiazol-2-yl)pyrazolo[3,4-d]pyrimidine.
Scheme 60: One pot POCl3-catalyzed synthesis of 1-arylpyrazolo[3,4-d]pyrimidin-4-ones.
Scheme 61: Synthesis of 4-amino-N1,C3-dialkylpyrazolo[3,4-d]pyrimidines under Suzuki conditions.
Scheme 62: Microwave-assisted synthesis of pyrazolo[3,4-b]pyrazines.
Scheme 63: Synthesis and derivatization of pyrazolo[3,4-b]pyrazine-5-carbonitriles.
Scheme 64: Synthesis of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones.
Scheme 65: Synthesis of 2,3-dihydropyrazolo[1,5-a][1,3,5]triazin-4(1H)-one.
Scheme 66: Synthesis of pyrazolo[1,5-a][1,3,5]triazine-8-carboxylic acid ethyl ester.
Scheme 67: Microwave-assisted synthesis of 4,7-dihetarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 68: Alternative synthetic route to 4,7-diheteroarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 69: Synthesis of 4-aryl-2-ethylthio-7-methylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 70: Microwave-assisted synthesis of 4-aminopyrazolo[1,5-a][1,3,5]triazine.
Scheme 71: Synthesis of pyrazolo[3,4-d][1,2,3]triazines from pyrazol-5-yl diazonium salts.
Scheme 72: Synthesis of 2,5-dihydropyrazolo[3,4-e][1,2,4]triazines.
Scheme 73: Synthesis of pyrazolo[5,1-c][1,2,4]triazines via diazopyrazolylenaminones.
Scheme 74: Synthesis of pyrazolo[5,1-c][1,2,4]triazines in presence of sodium acetate.
Scheme 75: Synthesis of various 7-diazopyrazolo[5,1-c][1,2,4]triazine derivatives.
Scheme 76: One pot synthesis of pyrazolo[5,1-c][1,2,4]triazines.
Scheme 77: Synthesis of 4-amino-3,7,8-trinitropyrazolo-[5,1-c][1,2,4]triazines.
Scheme 78: Synthesis of tricyclic pyrazolo[5,1-c][1,2,4]triazines by azocoupling reaction.
Progress in copper-catalyzed trifluoromethylation
- Guan-bao Li,
- Chao Zhang,
- Chun Song and
- Yu-dao Ma
Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11
- was characterized by X-ray crystallography. Aryl iodides, which contained nitrile, ketone, aldehyde, ester, methyl, phenyl groups, etc., were successfully reacted with this trifluoromethylation reagent to give the corresponding products in moderate to high yields. Also, a broad spectrum of heteroaryl
Graphical Abstract
Figure 1: Selected examples of pharmaceutical and agrochemical compounds containing the trifluoromethyl group....
Scheme 1: Introduction of a diamine into copper-catalyzed trifluoromethylation of aryl iodides.
Scheme 2: Addition of a Lewis acid into copper-catalyzed trifluoromethylation of aryl iodides and the propose...
Scheme 3: Trifluoromethylation of heteroaromatic compounds using S-(trifluoromethyl)diphenylsulfonium salts a...
Scheme 4: The preparation of a new trifluoromethylation reagent and its application in trifluoromethylation o...
Scheme 5: Trifluoromethylation of aryl iodides using CF3CO2Na as a trifluoromethyl source.
Scheme 6: Trifluoromethylation of aryl iodides using MTFA as a trifluoromethyl source.
Scheme 7: Trifluoromethylation of aryl iodides using CF3CO2K as a trifluoromethyl source.
Scheme 8: Trifluoromethylation of aryl iodides and heteroaryl bromides using [Cu(phen)(O2CCF3)] as a trifluor...
Scheme 9: Trifluoromethylation of aryl iodides with DFPB and the proposed mechanism.
Scheme 10: Trifluoromethylation of aryl iodides using TCDA as a trifluoromethyl source. Reaction conditions: [...
Scheme 11: The mechanism of trifluoromethylation using Cu(II)(O2CCF2SO2F)2 as a trifluoromethyl source.
Scheme 12: Trifluoromethylation of benzyl bromide reported by Shibata’s group.
Scheme 13: Trifluoromethylation of allylic halides and propargylic halides reported by the group of Nishibayas...
Scheme 14: Trifluoromethylation of propargylic halides reported by the group of Nishibayashi.
Scheme 15: Trifluoromethylation of alkyl halides reported by Nishibayashi’s group.
Scheme 16: Trifluoromethylation of pinacol esters reported by the group of Gooßen.
Scheme 17: Trifluoromethylation of primary and secondary alkylboronic acids reported by the group of Fu.
Scheme 18: Trifluoromethylation of boronic acid derivatives reported by the group of Liu.
Scheme 19: Trifluoromethylation of organotrifluoroborates reported by the group of Huang.
Scheme 20: Trifluoromethylation of aryl- and vinylboronic acids reported by the group of Shibata.
Scheme 21: Trifluoromethylation of arylboronic acids via the merger of photoredox and Cu catalysis.
Scheme 22: Trifluoromethylation of arylboronic acids reported by Sanford’s group. Isolated yield. aYields dete...
Scheme 23: Trifluoromethylation of arylboronic acids and vinylboronic acids reported by the group of Beller. Y...
Scheme 24: Copper-mediated Sandmeyer type trifluoromethylation using Umemoto’s reagent as a trifluoromethylati...
Scheme 25: Copper-mediated Sandmeyer type trifluoromethylation using TMSCF3 as a trifluoromethylation reagent ...
Scheme 26: One-pot Sandmeyer trifluoromethylation reported by the group of Gooßen.
Scheme 27: Copper-catalyzed trifluoromethylation of arenediazonium salts in aqueous media.
Scheme 28: Copper-mediated Sandmeyer trifluoromethylation using Langlois’ reagent as a trifluoromethyl source ...
Scheme 29: Trifluoromethylation of terminal alkenes reported by the group of Liu.
Scheme 30: Trifluoromethylation of terminal alkenes reported by the group of Wang.
Scheme 31: Trifluoromethylation of tetrahydroisoquinoline derivatives reported by Li and the proposed mechanis...
Scheme 32: Trifluoromethylation of phenol derivatives reported by the group of Hamashima.
Scheme 33: Trifluoromethylation of hydrazones reported by the group of Baudoin and the proposed mechanism.
Scheme 34: Trifluoromethylation of benzamides reported by the group of Tan.
Scheme 35: Trifluoromethylation of heteroarenes and electron-deficient arenes reported by the group of Qing an...
Scheme 36: Trifluoromethylation of N-aryl acrylamides using CF3SO2Na as a trifluoromethyl source.
Scheme 37: Trifluoromethylation of aryl(heteroaryl)enol acetates using CF3SO2Na as the source of CF3 and the p...
Scheme 38: Trifluoromethylation of imidazoheterocycles using CF3SO2Na as a trifluoromethyl source and the prop...
Scheme 39: Copper-mediated trifluoromethylation of terminal alkynes using TMSCF3 as a trifluoromethyl source a...
Scheme 40: Improved copper-mediated trifluoromethylation of terminal alkynes reported by the group of Qing.
Scheme 41: Copper-catalyzed trifluoromethylation of terminal alkynes reported by the group of Qing.
Scheme 42: Copper-catalyzed trifluoromethylation of terminal alkynes using Togni’s reagent and the proposed me...
Scheme 43: Copper-catalyzed trifluoromethylation of terminal alkynes using Umemoto’s reagent reported by the g...
Scheme 44: Copper-catalyzed trifluoromethylation of 3-arylprop-1-ynes reported by Xiao and Lin and the propose...
Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications
- Mattias Bood,
- Sangamesh Sarangamath,
- Moa S. Wranne,
- Morten Grøtli and
- L. Marcus Wilhelmsson
Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7
- led to the development of a large number of techniques for such investigations. Among the most significant ones are NMR [1] and X-ray crystallography [2]. Both techniques offer a high structure resolution and NMR can also provide information on dynamics. However, there are occasions where NMR and X
- -ray crystallography suffer from drawbacks: the sample amount requirement and biomolecular size restriction for NMR and the difficulties in obtaining crystals and the obvious lack of solution dynamics for X-ray crystallography. An important method for biomolecular structure and dynamics investigations
- Å, respectively [25]. This is in contrast to previously reported values showing slight increases in helical twist and rise measured, for example, by sedimentation [77], gel electrophoresis [78][79], X-ray crystallography [74] and magnetic tweezers [75]. In our investigation we modeled the general
Graphical Abstract
Figure 1: a) Angles and unit vectors used to define the relative orientations of the donor and acceptor trans...
Figure 2: Notable recent examples of fluorescent base analogues. For cnA and dnA the attachment point to the ...
Scheme 1: Synthesis of the tricyclic cytosine aromatic core [39]. (a) Ethylene glycol, K2CO3, 120 °C, 1 h, 40%; (...
Scheme 2: Synthesis of protected tC and tCO deoxyribose phosphonates [41]. (a) Ac2O, pyridine, rt; (b) 2-mesityle...
Scheme 3: Synthesis of protected tCnitro deoxyribose phosphoramidite [14]. a) aq NaOH, 24 h, reflux; b) EtOH, HCl...
Scheme 4: Improved synthesis of tC and tC derivatives, where R = H, 7-MeO or 8-MeO [47]. a) H2NNH2 followed by H2O...
Scheme 5: Improved synthesis of tCO derivatives [47]. a) Ac2O, pyridine, 16 h, rt, 85%; b) PPh3, CCl4, DCM, 5 h, ...
Scheme 6: Synthesis of protected tCO ribose phosphoramidite [50]. a) MesSO2Cl, DIPEA, MeCN, 4 h, rt; b) 2-aminoph...
Scheme 7: Synthesis of protected deoxyribose qA [51]. a) N-(tert-Butoxycarbonyl)-2-(trimethylstannyl)aniline, (Ph3...
Scheme 8: Synthesis of protected deoxyribose qA for DNA SPS [53]. a) AcCl, MeOH, rt, 40 min; b) p-toluoyl chlorid...
Scheme 9: Synthesis of qA derivatives. a) EtI, Cs2CO3, DMF, 4 h, rt, 90%; b) HBPin, Pd(PPh3)4, Et3N, 1,4-diox...
Scheme 10: Synthesis of quadracyclic adenine base–base FRET pair. a) HCHO, NaOH, MeCN, H2O, 50 °C, 1 h; b) TBD...
Figure 3: Absorption and emission of tC (dashed line) and tCO (solid line) in dsDNA. The absorption below 300...
Figure 4: Spectral overlap between the emission of qAN1 (cyan) and the absorption of qAnitro (black) in dsDNA...
Figure 5: Example of typical FRET efficiency as a function of number of base pairs separating the donor and a...
Figure 6: FRET efficiency as a function of number of base pairs separating the donor (qAN1) and acceptor (qAn...
Stereochemical outcomes of C–F activation reactions of benzyl fluoride
- Neil S. Keddie,
- Pier Alexandre Champagne,
- Justine Desroches,
- Jean-François Paquin and
- David O'Hagan
Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6
- stereochemistry of 12 was confirmed by X-ray crystallography of the 4-bromophenyl ester derivative 13. Alcohol 12 was activated as the tosyl ester at −20 °C, and then immediately displaced by LiAlD4 [17], inverting the stereocenter to afford the (S)-diarylmethane 10 isotopomer in 18% ee. 2H{1H} NMR in a PBLG
Graphical Abstract
Figure 1: C–F activation of benzylic fluorides to generate benzylamine or diarylmethane products.
Figure 2: 7-[2H1]-(R)-Benzyl fluoride ((R)-1).
Scheme 1: Synthesis of enantioenriched 7-[2H1]-(R)-benzyl fluoride ((R)-1) from benzaldehyde (2).
Figure 3: Partial 2H{1H} NMR (107.5 MHz) with PBLG in CHCl3 (13% w/w). (A) racemic sample of 6 (from Table 1, entry ...
Scheme 2: Synthesis of enantioenriched (S)-diarylmethane 10 from diaryl ketone 11 and confirmation of configu...
Figure 4: Possible reactive intermediates for C–F activation of benzyl fluoride 1 with strong hydrogen bond d...
