Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate
- Mysore Bhyrappa Harisha,
- Pandi Dhanalakshmi,
- Rajendran Suresh,
- Raju Ranjith Kumar and
- Shanmugam Muthusubramanian
Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178
Graphical Abstract
Figure 1: Examples of biologically active oxazole and aminothiazole scaffolds.
Scheme 1: Strategies for the synthesis of 2,4,5-trisubstituted oxazole from azirine. a) I2, PPh3; b) NaH, 1H-...
Scheme 2: Scope of the α-azidochalcones. The reactions were carried out at reflux temperature, using 1 (1 mmo...
Scheme 3: Large-scale synthesis of 3i.
Figure 2: Large-scale synthesis of 3i. a) At the start of the reaction, b) after the reaction.
Scheme 4: Acetyl derivative of 3d.
Figure 3: ORTEP diagram of compound 5.
Scheme 5: Synthesis of S-methyl/benzylated products 6 and 7.
Scheme 6: Control experiments.
Scheme 7: Plausible mechanism proposed for the formation of 2,4,5-trisubstituted oxazoles 3.
Scheme 8: Reaction of vinyl azide 1 and 3 with ferric nitrate. Reactions were carried out at reflux temperatu...
Figure 4: X-ray crystal structure of 4h.
Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst
- Jannis Ludwig,
- Julian Helberg,
- Hendrik Zipse and
- Rainer Herges
Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179
Graphical Abstract
Figure 1: Basicity and nucleophilicity switching of the 4-(N,N-dimethylamino)pyridine “record player” molecul...
Scheme 1: Synthesis of 4-N,N-dimethylamino record player molecule 1 by Suzuki reaction between Ni-porphyrin p...
Figure 2: Composition of the different states of porphyrin 1 (1 mM) in the PSS at 530 nm and 435 nm, determin...
Figure 3: a) UV–vis cuvette with a solution of porphyrin 1 (13.1 µM in THF) and the corresponding UV–vis spec...
Scheme 2: General scheme of the nitroaldol (Henry) reaction that was used to investigate photoswitchable cata...
Scheme 3: DMAP (2), azopyridine trans-4, record player trans- and cis-1 and Ni-porphyrin 8 were used in kinet...
Figure 4: Conversion of 4-nitrobenzaldehyde (6) in the Henry reaction with nitroethane (5) as a function of t...
GlypNirO: An automated workflow for quantitative N- and O-linked glycoproteomic data analysis
- Toan K. Phung,
- Cassandra L. Pegg and
- Benjamin L. Schulz
Beilstein J. Org. Chem. 2020, 16, 2127–2135, doi:10.3762/bjoc.16.180
Graphical Abstract
Figure 1: Evaluation of GlypNirO site-specific N-glycosylation profiling. Site-specific relative glycoform ab...
Figure 2: N-Glycoproteome profiling with GlypNirO. Volcano plots of site-specific N-glycoform relative abunda...
Figure 3: Site-specific N-glycopeptide profiling with GlypNirO. Site-specific relative glycoform abundance in...
Figure 4: O-Glycoproteome profiling with GlypNirO. Volcano plots of site-specific O-glycoform relative abunda...
Figure 5: Peptide-specific O-glycosylation profiling with GlypNirO. Peptide-specific relative glycoform abund...
Synthesis of 6,13-difluoropentacene
- Matthias W. Tripp and
- Ulrich Koert
Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181
Graphical Abstract
Figure 1: Structures of pentacene and fluorinated pentacenes.
Scheme 1: Retrosynthetic analysis of F2PEN 5.
Scheme 2: Synthesis of F2PEN 5.
Scheme 3: Decomposition of diol 13 in solution.
Figure 2: UV–vis spectrum of F2PEN 5 in CH2Cl2.
Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups
- Benjamin Jeffries,
- Zhong Wang,
- Robert I. Troup,
- Anaïs Goupille,
- Jean-Yves Le Questel,
- Charlene Fallan,
- James S. Scott,
- Elisabetta Chiarparin,
- Jérôme Graton and
- Bruno Linclau
Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182
Graphical Abstract
Figure 1: Examples of lipophilicity modulation for geminal dimethyl to cyclopropyl and oxetane modifications ...
Figure 2: Lipophilicity modulation examples involving fluorinated cyclopropane derivatives (measured experime...
Figure 3: Lipophilicity changes upon fluorination of isopropyl, cyclopropane and oxetane rings (Series A, C: ...
Figure 4: Lipophilicity modulations discussed in this contribution.
Figure 5: Distribution of the experimental lipophilicity values of series D, E and F (* denotes an estimated ...
Figure 6: Comparison of lipophilicities between the linear alkyl, isopropyl, cyclopropyl, and 3-oxetanyl subs...
Figure 7: Comparison of lipophilicities between isopropyl and cyclopropyl substituents grouped by exchange of...
Figure 8: Carbon extensions.
Figure 9: Experimental and theoretical (in blue) values (calculated at the MN15/aug-cc-pVTZ//MN15/cc-pVTZ lev...
Figure 10: Correlation of the DFT-calculated lipophilicities with the experimental values. A) fluorinated seri...
Figure 11: Experimental (in black) and theoretical (in blue) values (calculated at the MN15/aug-cc-pVTZ//MN15/...
Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis
- Shahboz Yakubov and
- Joshua P. Barham
Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183
Graphical Abstract
Figure 1: Fluorine-containing drugs.
Figure 2: Fluorinated agrochemicals.
Scheme 1: Selectivity of fluorination reactions.
Scheme 2: Different mechanisms of photocatalytic activation. Sub = substrate.
Figure 3: Jablonski diagram showing visible-light-induced energy transfer pathways: a) absorption, b) IC, c) ...
Figure 4: Schematic illustration of TTET.
Figure 5: Organic triplet PSCats.
Figure 6: Additional organic triplet PSCats.
Figure 7: A) Further organic triplet PSCats and B) transition metal triplet PSCats.
Figure 8: Different fluorination reagents grouped by generation.
Scheme 3: Synthesis of Selectfluor®.
Scheme 4: General mechanism of PS TTET C(sp3)–H fluorination.
Scheme 5: Selective benzylic mono- and difluorination using 9-fluorenone and xanthone PSCats, respectively.
Scheme 6: Chen’s photosensitized monofluorination: reaction scope.
Scheme 7: Chen’s photosensitized benzylic difluorination reaction scope.
Scheme 8: Photosensitized monofluorination of ethylbenzene on a gram scale.
Scheme 9: Substrate scope of Tan’s AQN-photosensitized C(sp3)–H fluorination.
Scheme 10: AQN-photosensitized C–H fluorination reaction on a gram scale.
Scheme 11: Reaction mechanism of the AQN-assisted fluorination.
Figure 9: 3D structures of the singlet ground and triplet excited states of Selectfluor®.
Scheme 12: Associated transitions for the activation of acetophenone by violet light.
Scheme 13: Ethylbenzene C–H fluorination with various PSCats and conditions.
Scheme 14: Effect of different PSCats on the C(sp3)–H fluorination of cyclohexane (39).
Scheme 15: Reaction scope of Chen’s acetophenone-photosensitized C(sp3)–H fluorination reaction.
Figure 10: a) Site-selectivity of Chen’s acetophenone-photosensitized C–H fluorination reaction [201]. b) Site-sele...
Scheme 16: Formation of the AQN–Selectfluor® exciplex Int1.
Scheme 17: Generation of the C3 2° pentane radical and the Selectfluor® N-radical cation from the exciplex.
Scheme 18: Hydrogen atom abstraction by the Selectfluor® N-radical cation from pentane to give the C3 2° penta...
Scheme 19: Fluorine atom transfer from Selectfluor® to the C3 2° pentane radical to yield 3-fluoropentane and ...
Scheme 20: Barrierless fluorine atom transfer from Int1 to the C3 2° pentane radical to yield 3-fluoropentane,...
Scheme 21: Ketone-directed C(sp3)–H fluorination.
Scheme 22: Ketone-directed fluorination through a 5- and a 6-membered transition state, respectively.
Scheme 23: Effect of different PSCats on the photosensitized C(sp3)–H fluorination of 47.
Scheme 24: Substrate scope of benzil-photoassisted C(sp3)–H fluorinations.
Scheme 25: A) Benzil-photoassisted enone-directed C(sp3)–H fluorination. B) Classification of the reaction mod...
Scheme 26: A) Xanthone-photoassisted ketal-directed C(sp3)–H fluorination. B) Substrate scope. C) C–H fluorina...
Scheme 27: Rationale for the selective HAT at the C2 C–H bond of galactose acetonide.
Scheme 28: Photosensitized C(sp3)–H benzylic fluorination of a peptide using different PSCats.
Scheme 29: Peptide scope of 5-benzosuberenone-photoassisted C(sp3)–H fluorinations.
Scheme 30: Continuous flow PS TTET monofluorination of 72.
Scheme 31: Photosensitized C–H fluorination of N-butylphthalimide as a PSX.
Scheme 32: Substrate scope and limitations of the PSX C(sp3)–H monofluorination.
Scheme 33: Substrate crossover monofluorination experiment.
Scheme 34: PS TTET mechanism proposed by Hamashima and co-workers.
Scheme 35: Photosensitized TFM of 78 to afford α-trifluoromethylated ketone 80.
Scheme 36: Substrate scope for photosensitized styrene TFM to give α-trifluoromethylated ketones.
Scheme 37: Control reactions for photosensitized TFM of styrenes.
Scheme 38: Reaction mechanism for photosensitized TFM of styrenes to afford α-trifluoromethylated ketones.
Scheme 39: Reaction conditions for TFMs to yield the cis- and the trans-product, respectively.
Scheme 40: Substrate scope of trifluoromethylated (E)-styrenes.
Scheme 41: Strategies toward trifluoromethylated (Z)-styrenes.
Scheme 42: Substrate scope of trifluoromethylated (Z)-styrenes.
Scheme 43: Reaction mechanism for photosensitized TFM of styrenes to afford E- or Z-products.
Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols
- Tatsuya Kumon,
- Miroku Shimada,
- Jianyan Wu,
- Shigeyuki Yamada and
- Tsutomu Konno
Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184
Graphical Abstract
Figure 1: Indenol skeleton.
Scheme 1: Synthesis of 2,3-disubstituted indene derivatives.
Scheme 2: Cobalt-catalyzed [2 + 3] cycloaddition reaction of the fluorinated alkynes 1 with various 2-formylp...
Scheme 3: Synthesis of the fluoroalkylated indenone 6 and the indanone 7 from the indenol 3aA. The yields wer...
Scheme 4: Stereochemical assignment of 5aA and 7 based on NMR techniques. The cross-peaks were observed throu...
Scheme 5: Proposed reaction mechanism.
Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator
- Poulami Jana,
- Filip Šupljika,
- Carsten Schmuck and
- Ivo Piantanida
Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185
Graphical Abstract
Scheme 1: DNA-targeting roles of the structural components incorporated in the design of the novel small mole...
Scheme 2: Synthesis of compound 4. Conditions: a) mono-N-Boc-ethylenediamine, DMF, 90 °C; b) i) trifluoroacet...
Figure 1: UV–vis titrations of compound 4 (c = 1.0 × 10−6 M), with ct-DNA at pH 7.0 (a) and at pH 5 (b). Inse...
Figure 2: a) CD titration of ct-DNA (c = 3.0 × 10−5 M) with compound 4 at pH 7.0 (Na cacodylate buffer, I = 0...
Figure 3: CD titration of poly(rA)–poly(rU) (c = 3.0 × 10−5 M) with compound 4 at a) pH 7.0 (Na cacodylate bu...
Figure 4: CD titration of ds-DNAs (c = 3.0 × 10−5 M) with 4 for ratio r[4]/ [DNA] = 0.4. Done at pH 5.0 (Na c...
Figure 5: ITC experiments of poly(dAdT)–poly(dAdT) (c = 5.0 × 10−5 M) titrated with compound 4. Dots represen...
Figure 6: AFM image of a) ct-DNA showing a fibre-like structure with a length of several micrometres; b) upon...
Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186
Graphical Abstract
Figure 1: Representation of corannulene (1) and sumanene (2), the subunits of fullerene (C60).
Scheme 1: Mehta’s unsuccessful effort for the synthesis of sumanene scaffold 2.
Scheme 2: First synthesis of sumanene 2 by Sakurai et al. from norbornadiene 10.
Scheme 3: Synthesis of trimethylsumanene 28 from easily accessible norbornadiene (10).
Scheme 4: Generation of anions 29–31 and the preparation of tris(trimethylsilyl)sumanene 32.
Scheme 5: Synthesis of tri- and hexa-substituted sumanene derivatives.
Scheme 6: Synthesis of bowl-shaped π-extended sumanene derivatives 37a–f.
Scheme 7: Synthesis of monooxasumanene 38, trioxosumanene 40 along with imination of them.
Scheme 8: Synthesis of trimethylsumanenetrione 46 and exo-functionalized products 45a,b.
Scheme 9: Synthesis of bisumanenylidene 47 and sumanene dimer 48 from 2.
Scheme 10: The mono-substitution of 2 to generate diverse mono-sumanene derivatives 49a–d.
Scheme 11: Synthesis of sumanene building block 53 useful for further extension.
Scheme 12: Synthesis of hexafluorosumanene derivative 55 by Sakurai and co-workers.
Scheme 13: Preparation of sumanene-based carbene 60 and its reaction with cyclohexane.
Scheme 14: Barton–Kellogg reaction for the synthesis of sterically hindered alkenes.
Scheme 15: Synthesis of hydroxysumanene 68 by employing Baeyer–Villiger oxidation.
Scheme 16: Synthesis of sumanene derivatives having functionality at an internal carbon.
Scheme 17: Mechanism for nucleophilic substitution reaction at the internal carbon.
Scheme 18: Synthesis of diverse monosubstituted sumanene derivatives.
Scheme 19: Synthesis of di- and trisubstituted sumanene derivatives from sumanene (2).
Scheme 20: Preparation of monochlorosumanene 88 and hydrogenation of sumanene (2).
Scheme 21: The dimer 90 and bissumanenyl 92 achieved from halosumannes.
Scheme 22: Pyrenylsumanene 93 involving the Suzuki-coupling as a key transformation.
Scheme 23: Synthesis of various hexaarylsumanene derivatives using the Suzuki-coupling reaction.
Scheme 24: Synthesis of hexasubstituted sumanene derivatives 96 and 97.
Scheme 25: Synthesis of thioalkylsumanenes via an aromatic nucleophilic substitution reaction.
Scheme 26: Synthesis of tris(ethoxycarbonylethenyl)sumanene derivative 108.
Scheme 27: Synthesis of ferrocenyl-based sumanene derivatives.
Scheme 28: Synthesis of sumanenylferrocene architectures 118 and 119 via Negishi coupling.
Scheme 29: Diosmylation and the synthesis of phenylboronate ester 121 of sumanene.
Scheme 30: Synthesis of the iron-complex of sumanene.
Scheme 31: Synthesis of tri- and mononuclear sumanenyl zirconocene complexes.
Scheme 32: Synthesis of [CpRu(η6-sumanene)]PF6.
Scheme 33: Preparation of sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (...
Scheme 34: Synthesis of sumanenylhafnocene complexes 129 and 130.
Scheme 35: Synthesis of 134 and 135 along with PdII coordination complex 136.
Scheme 36: Synthesis of alkali metals sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) containing di- and tr...
Scheme 37: The encapsulation of a Cs+ ion between two sumanenyl anions.
Scheme 38: Synthesis of monothiasumanene 140 and dithiasumanene 141 from 139.
Scheme 39: Synthesis of trithiasumanene 151 by Otsubo and his co-workers.
Scheme 40: Synthesis of trithiasumanene derivatives 155 and 156.
Scheme 41: Synthetic route towards hexathiolated trithiasumanenes 158.
Scheme 42: Synthesis of triselenasumanene 160 by Shao and teammates.
Scheme 43: Synthesis of tritellurasumanene derivatives from triphenylene skeletons.
Scheme 44: Synthesis of pyrazine-fused sumanene architectures through condensation reaction.
Scheme 45: Treatment of the trichalcogenasumanenes with diverse oxidative reagents.
Scheme 46: Ring-opening reaction with H2O2 and oxone of heterasumanenes 178 and 179.
Scheme 47: Synthesis of polycyclic compounds from sumanene derivatives.
Scheme 48: Synthesis of diimide-based heterocycles reported by Shao’s and co-workers.
Scheme 49: Synthesis of pristine trichalcogenasumanenes, 151, 205, and 206.
Scheme 50: Synthesis of trichalcogenasumanenes via hexaiodotriphenylene precursor 208.
Scheme 51: Synthesis of trisilasumanenes 214 and 215.
Scheme 52: Synthesis of trisilasumanene derivatives 218 and 219.
Scheme 53: Synthesis of novel trigermasumanene derivative 223.
Scheme 54: An attempt towards the synthesis of tristannasumanene derivative 228.
Scheme 55: Synthesis of triphosphasumanene trisulfide 232 from commercially available 229.
Scheme 56: The doping of sumanene derivatives with chalcogens (S, Se, Te) and phosphorus.
Scheme 57: Synthesis of heterasumanene containing three different heteroatoms.
Scheme 58: Synthesis of trichalcogenasumanene derivatives 240 and 179.
Scheme 59: Preparation of trichalcogenasumanenes 245 and 248.
Scheme 60: Design and synthesis of trichalcogenasumanene derivatives 252 and 178.
Scheme 61: Synthesis of spirosumanenes 264–269 and non-spiroheterasumanenes 258–263.
Scheme 62: Synthesis of sumanene-type hetero polycyclic compounds.
Scheme 63: Synthesis of triazasumanenes 288 and its sulfone congener 287.
Scheme 64: Synthesis of C3-symmetric chiral triaryltriazasumanenes via cross-coupling reaction.
Scheme 65: Synthesis of mononaphthosumanene 293 using Suzuki coupling as a key step.
Scheme 66: Synthesis of di- and trinaphthosumanene derivatives 302–304.
Scheme 67: Synthesis of hemifullerene skeletons by Hirao’s group.
Scheme 68: Design and construction of C70 fragment from a C60 sumanene fragment.
Tools for generating and analyzing glycan microarray data
- Akul Y. Mehta,
- Jamie Heimburg-Molinaro and
- Richard D. Cummings
Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187
Graphical Abstract
Figure 1: Overview of a typical glycan microarray workflow, beginning with the obtention of glycans to analys...
Figure 2: A decision tree to determine which type of surface to use depending on glycoconjugate and linker ty...
Figure 3: Screenshot of microarray databases: (A) Screenshot of an example of CFG glycan array data; (B) scre...
Figure 4: A demonstration of glycan array data visualization with GLAD. The dataset used is from Byrd-Leotis ...
The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY
- Patrizia Andreozzi,
- Lorenza Tamberi,
- Elisamaria Tasca,
- Gina Elena Giacomazzo,
- Marta Martinez,
- Mirko Severi,
- Marco Marradi,
- Stefano Cicchi,
- Sergio Moya,
- Giacomo Biagiotti and
- Barbara Richichi
Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188
Graphical Abstract
Figure 1: Structure of PBA-BODIPY (1) and schematic representation of dextran (Dex) and PBA-BODIPY conjugated...
Scheme 1: Schematic representation of dextran/PBA-BODIPY bioconjugations in: A. conventional solution-based c...
Figure 2: A) Amount of recovered PBA-BODIPY (1, i.e., nonreacted 1) in the mixtures DMSO/EtOH and in the seri...
Figure 3: A) UV–vis absorption and B) fluorescence emission spectra (λexc = 380 nm) of the BODIPY-dextran con...
Figure 4: A) Hydrodynamic diameter of (nm) conjugate Dex-1b (at 1 mg/mL in H2O, black curve) and PBS (red cur...
Figure 5: Fluorescence emission spectra of pyrene (4.4 × 10−8 M) in water and in a water solution in the pres...
Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties
- Anka Utama Putra,
- Deniz Çakmaz,
- Nurgül Seferoğlu,
- Alberto Barsella and
- Zeynel Seferoğlu
Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189
Graphical Abstract
Scheme 1: Synthetic pathways of dyes 3–7 and Schiff base analogs 8–12.
Figure 1: The optimized geometry of dyes 3 and 8.
Figure 2: Absorption spectra of dyes 3 (a, left) and 8 (b, right). Inset: Color of dyes 3 and 8 in the given ...
Figure 3: Emission spectra of dyes 3 (a, left) and 8 (b, right). Inset: Color of dyes 3 and 8 in the indicate...
Figure 4: Red shift phenomena with changing substituents in absorption (a, left) and emission (b, right) spec...
Figure 5: Absorption (a, left) and emission (b, right) change of dye 12 upon addition of 15 equiv of TBAOH an...
Figure 6: Photographs of dye 12 (left, ambient light), without, after the addition of 15 equiv of TBAOH (midd...
Figure 7: Absorption (a, left) and emission (b, right) change of 8 in Britton–Robinson buffer solutions at di...
Figure 8: Photographs of dye 8 in Britton–Robinson buffer solutions at different pH values.
Figure 9: Sigmoid function obtained from dye 8 UV–vis absorption spectra during pH investigation.
Figure 10: TGA curves of all synthetized dyes.
Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores
- Asitanga Ghosh
Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190
Graphical Abstract
Figure 1: Model mixed enones.
Scheme 1: Quantitative photoisomerization of 1 to 2 in all types of solvents.
Scheme 2: Accepted mechanistic pathway for the photochemical transformations of 1.
Scheme 3: Photochemical reactions of 3a–g. Irradiation using a Hanovia medium pressure 450 W lamp with a pyre...
Figure 2: Enones used for this work.
Scheme 4: Synthesis of 7a,b.
Scheme 5: Photochemical reaction of 7a,b; a) solvent and conditions are given in Table 2.
Figure 3: Time-dependent absorption spectra of 10a,b in acetonitrile at rt.
Scheme 6: Conversion of ketene 10a to its methyl esters 11a,b.
Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones
- Viktor M. Tkachuk,
- Oleh O. Lukianov,
- Mykhailo V. Vovk,
- Isabelle Gillaizeau and
- Volodymyr A. Sukach
Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191
Graphical Abstract
Figure 1: Summary of the previous and present studies.
Scheme 1: Chan–Evans–Lam reaction of 4-trifluoromethylpyrimidin-2(1H)-one 1а with (het)aryl boronic acid 2b–w...
Scheme 2: Chan–Evans–Lam reaction of 4-trifluoromethylpyrimidin-2(1H)-one (1а) with (het)aryl- and alkenylbor...
Scheme 3: Chan–Evans–Lam reaction of pyrimidin-2(1H)-ones 1b–h with phenylboronic acid (2a).
Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots
- Elizabeth A. Margolis,
- Rebecca J. Keyes,
- Stephen D. Lockey IV and
- Edward E. Fenlon
Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192
Graphical Abstract
Figure 1: Structures of electron-rich bis-macrocyclic host 1, and electron-poor guests bis(ammonium) 2, and b...
Figure 2: (a) Hunter’s 77 backbone-atom trefoil knot–metal complex [9]. (b) The world’s smallest knot: Leigh’s 7...
Figure 3: Schematic representation of the second-generation TLC approach to a 73 backbone atom trefoil knot.
Scheme 1: Two routes to azidobromide 6.
Scheme 2: Initial route to core diester 13. aLigand = tris(2-benzimidazolylmethyl)amine.
Scheme 3: Better yielding route to core diester 13. aLigand = tris(2-benzimidazolylmethyl)amine.
Scheme 4: Saponification of 13 and bis-macrocyclization to form host 1.
Scheme 5: Synthesis of 23 backbone-atom bis(ammonium) guest 2.
Scheme 6: Synthesis of 25 backbone-atom bis(pyridinium) guest 3.
Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol
- Ekaterina E. Stepanova,
- Maksim V. Dmitriev and
- Andrey N. Maslivets
Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193
Graphical Abstract
Figure 1: Enaminones fused to heterocyclic moieties.
Scheme 1: Reported structure A of assayed compound [9] and its correct structure B.
Scheme 2: Known synthetic approaches to BTAs III.
Scheme 3: General synthetic approaches to enaminones I and II.
Scheme 4: Reported reactions of acylpyruvic acids or their esters IV with o-aminothiophenol (1a) [27,28].
Scheme 5: Plausible mechanism of the reaction of acylpyruvic acid 2a with o-aminothiophenol (1a) in the prese...
Scheme 6: The substrate scope of the optimized approach to BTAs 3a–n. Procedure: to a cooled to 0–5 °C stirri...
Scheme 7: The substrate scope of the optimized approach to compounds 4a–n. Procedure: to a stirring solution ...
Scheme 8: Plausible scheme of the formation of diketone 6.
Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A
- Zhishu Zeng,
- Jun Xie,
- Guangyan Luo,
- Zhu Tao and
- Qianjun Zhang
Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194
Graphical Abstract
Figure 1: The molecular structure of OA (A) and Q[8] (B).
Figure 2: 1H NMR titration of OA with Q[8] were performed in D2O containing 10% DMSO by volume, OA (500 μmol·L...
Figure 3: (A) The UV–vis absorption spectra recorded for OA in the presence of Q[8] (c(Q[8]), labeled a–k: 0,...
Figure 4: IR spectra recorded for (a) Q[8], (b) OA, (c) a physical mixture of Q[8] and OA, and (d) the OA@Q[8...
Figure 5: The possible interaction mode for OA@Q[8].
Figure 6: The phase-solubility graph obtained for OA in a Q[8] aqueous solution at λ = 275 nm.
Figure 7: The clearance rate curve of ABTS+• upon increasing the concentration of OA and the OA@Q[8] inclusio...
Figure 8: The release curves of OA and OA@Q[8].
Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis
- David Van Craen,
- Jenny Begall,
- Johannes Großkurth,
- Leonard Himmel,
- Oliver Linnenberg,
- Elisabeth Isaak and
- Markus Albrecht
Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195
Graphical Abstract
Scheme 1: Formation of hierarchically assembled lithium-bridged titanium(IV) helicates as well as the ligands...
Scheme 2: Previously reported on/off switch for “remote-controlled” [23-31] stereoselectivity of a Diels–Alder react...
Scheme 3: Elucidating the pathway of the stereoinduction of the Diels–Alder reaction. Ten equivalents of chir...
Scheme 4: Synthesis of the ligands with secondary amine-containing substituents.
A proposed sustainability index for synthesis plans based on input provenance and output fate: application to academic and industrial synthesis plans for vanillin as a case study
- John Andraos
Beilstein J. Org. Chem. 2020, 16, 2346–2362, doi:10.3762/bjoc.16.196
Graphical Abstract
Figure 1: Radial diamond diagrams illustrating the sustainability index (SI) computed based on FVI, FVO, FVP,...
Recent developments in enantioselective photocatalysis
- Callum Prentice,
- James Morrisson,
- Andrew D. Smith and
- Eli Zysman-Colman
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
Graphical Abstract
Scheme 1: Amine/photoredox-catalysed α-alkylation of aldehydes with alkyl bromides bearing electron-withdrawi...
Scheme 2: Amine/HAT/photoredox-catalysed α-functionalisation of aldehydes using alkenes.
Scheme 3: Amine/cobalt/photoredox-catalysed α-functionalisation of ketones and THIQs.
Scheme 4: Amine/photoredox-catalysed α-functionalisation of aldehydes or ketones with imines. (a) Using keton...
Scheme 5: Bifunctional amine/photoredox-catalysed enantioselective α-functionalisation of aldehydes.
Scheme 6: Bifunctional amine/photoredox-catalysed α-functionalisation of aldehydes using amine catalysts via ...
Scheme 7: Amine/photoredox-catalysed RCA of iminium ion intermediates. (a) Synthesis of quaternary stereocent...
Scheme 8: Bifunctional amine/photoredox-catalysed RCA of enones in a radical chain reaction initiated by an i...
Scheme 9: Bifunctional amine/photoredox-catalysed RCA reactions of iminium ions with different radical precur...
Scheme 10: Bifunctional amine/photoredox-catalysed radical cascade reactions between enones and alkenes with a...
Scheme 11: Amine/photocatalysed photocycloadditions of iminium ion intermediates. (a) External photocatalyst u...
Scheme 12: Amine/photoredox-catalysed addition of acrolein (94) to iminium ions.
Scheme 13: Dual NHC/photoredox-catalysed acylation of THIQs.
Scheme 14: NHC/photocatalysed spirocyclisation via photoisomerisation of an extended Breslow intermediate.
Scheme 15: CPA/photoredox-catalysed aza-pinacol cyclisation.
Scheme 16: CPA/photoredox-catalysed Minisci-type reaction between azaarenes and α-amino radicals.
Scheme 17: CPA/photoredox-catalysed radical additions to azaarenes. (a) α-Amino radical or ketyl radical addit...
Scheme 18: CPA/photoredox-catalysed reduction of azaarene-derived substrates. (a) Reduction of ketones. (b) Ex...
Scheme 19: CPA/photoredox-catalysed radical coupling reactions of α-amino radicals with α-carbonyl radicals. (...
Scheme 20: CPA/photoredox-catalysed Povarov reaction.
Scheme 21: CPA/photoredox-catalysed reactions with imines. (a) Decarboxylative imine generation followed by Po...
Scheme 22: Bifunctional CPA/photocatalysed [2 + 2] photocycloadditions.
Scheme 23: PTC/photocatalysed oxygenation of 1-indanone-derived β-keto esters.
Scheme 24: PTC/photoredox-catalysed perfluoroalkylation of 1-indanone-derived β-keto esters via a radical chai...
Scheme 25: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 26: Bifunctional hydrogen bonding/photocatalysed intramolecular RCA cyclisation of a quinolone.
Scheme 27: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 28: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloaddition reactions. (a) First use of...
Scheme 29: Bifunctional hydrogen bonding/photocatalysed deracemisation of allenes.
Scheme 30: Bifunctional hydrogen bonding/photocatalysed deracemisation reactions. (a) Deracemisation of sulfox...
Scheme 31: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloaddition of coumarins....
Scheme 32: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloadditions of quinolones. (a) Intramo...
Scheme 33: Hydrogen bonding/photocatalysed formal arylation of benzofuranones.
Scheme 34: Hydrogen bonding/photoredox-catalysed dehalogenative protonation of α,α-chlorofluoro ketones.
Scheme 35: Hydrogen bonding/photoredox-catalysed reductions. (a) Reduction of 1,2-diketones. (b) Reduction of ...
Scheme 36: Hydrogen bonding/HAT/photocatalysed deracemisation of cyclic ureas.
Scheme 37: Hydrogen bonding/HAT/photoredox-catalysed synthesis of cyclic sulfonamides.
Scheme 38: Hydrogen bonding/photoredox-catalysed reaction between imines and indoles.
Scheme 39: Chiral cation/photoredox-catalysed radical coupling of two α-amino radicals.
Scheme 40: Chiral phosphate/photoredox-catalysed hydroetherfication of alkenols.
Scheme 41: Chiral phosphate/photoredox-catalysed synthesis of pyrroloindolines.
Scheme 42: Chiral anion/photoredox-catalysed radical cation Diels–Alder reaction.
Scheme 43: Lewis acid/photoredox-catalysed cycloadditions of carbonyls. (a) Formal [2 + 2] cycloaddition of en...
Scheme 44: Lewis acid/photoredox-catalysed RCA reaction using a scandium Lewis acid between α-amino radicals a...
Scheme 45: Lewis acid/photoredox-catalysed RCA reaction using a copper Lewis acid between α-amino radicals and...
Scheme 46: Lewis acid/photoredox-catalysed synthesis of 1,2-amino alcohols from aldehydes and nitrones using a...
Scheme 47: Lewis acid/photocatalysed [2 + 2] photocycloadditions of enones and alkenes.
Scheme 48: Meggers’s chiral-at-metal catalysts.
Scheme 49: Lewis acid/photoredox-catalysed α-functionalisation of ketones with alkyl bromides bearing electron...
Scheme 50: Bifunctional Lewis acid/photoredox-catalysed radical coupling reaction using α-chloroketones and α-...
Scheme 51: Lewis acid/photocatalysed RCA of enones. (a) Using aldehydes as acyl radical precursors. (b) Other ...
Scheme 52: Bifunctional Lewis acid/photocatalysis for a photocycloaddition of enones.
Scheme 53: Lewis acid/photoredox-catalysed RCA reactions of enones using DHPs as radical precursors.
Scheme 54: Lewis acid/photoredox-catalysed functionalisation of β-ketoesters. (a) Hydroxylation reaction catal...
Scheme 55: Bifunctional copper-photocatalysed alkylation of imines.
Scheme 56: Copper/photocatalysed alkylation of imines. (a) Bifunctional copper catalysis using α-silyl amines....
Scheme 57: Bifunctional Lewis acid/photocatalysed intramolecular [2 + 2] photocycloaddition.
Scheme 58: Bifunctional Lewis acid/photocatalysed [2 + 2] photocycloadditions (a) Intramolecular cycloaddition...
Scheme 59: Bifunctional Lewis acid/photocatalysed rearrangement of 2,4-dieneones.
Scheme 60: Lewis acid/photocatalysed [2 + 2] cycloadditions of cinnamate esters and styrenes.
Scheme 61: Nickel/photoredox-catalysed arylation of α-amino acids using aryl bromides.
Scheme 62: Nickel/photoredox catalysis. (a) Desymmetrisation of cyclic meso-anhydrides using benzyl trifluorob...
Scheme 63: Nickel/photoredox catalysis for the acyl-carbamoylation of alkenes with aldehydes using TBADT as a ...
Scheme 64: Bifunctional copper/photoredox-catalysed C–N coupling between α-chloro amides and carbazoles or ind...
Scheme 65: Bifunctional copper/photoredox-catalysed difunctionalisation of alkenes with alkynes and alkyl or a...
Scheme 66: Copper/photoredox-catalysed decarboxylative cyanation of benzyl phthalimide esters.
Scheme 67: Copper/photoredox-catalysed cyanation reactions using TMSCN. (a) Propargylic cyanation (b) Ring ope...
Scheme 68: Palladium/photoredox-catalysed allylic alkylation reactions. (a) Using alkyl DHPs as radical precur...
Scheme 69: Manganese/photoredox-catalysed epoxidation of terminal alkenes.
Scheme 70: Chromium/photoredox-catalysed allylation of aldehydes.
Scheme 71: Enzyme/photoredox-catalysed dehalogenation of halolactones.
Scheme 72: Enzyme/photoredox-catalysed dehalogenative cyclisation.
Scheme 73: Enzyme/photoredox-catalysed reduction of cyclic imines.
Scheme 74: Enzyme/photocatalysed enantioselective reduction of electron-deficient alkenes as mixtures of (E)/(Z...
Scheme 75: Enzyme/photoredox catalysis. (a) Deacetoxylation of cyclic ketones. (b) Reduction of heteroaromatic...
Scheme 76: Enzyme/photoredox-catalysed synthesis of indole-3-ones from 2-arylindoles.
Scheme 77: Enzyme/HAT/photoredox catalysis for the DKR of primary amines.
Scheme 78: Bifunctional enzyme/photoredox-catalysed benzylic C–H hydroxylation of trifluoromethylated arenes.
