Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

Cristina Cebrián and
Matteo Mauro

Review
Published 18 Jun 2018

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1. Graphical Abstract
2. Figure 1: Molecular structure of neutral platinum(II) complex 1 bearing four monodentate ligands; cy = cycloh...
  
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3. Figure 2: Chemical structure of the dinuclear Pt complexes 2a–b and 3 [20].
  
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4. Figure 3: Molecular structure of platinum(II) complexes bearing isoquinolinylpyrazolates; dip = 2,6-diisoprop...
  
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5. Figure 4: Selected neutral platinum(II) complexes featuring dianionic biazolate and neutral bipyridines [27].
  
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6. Figure 5: Selected neutral platinum(II) complexes from bipyrazolate and carbene-based chelates [34,35].
  
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7. Figure 6: Cyclometalated thiazol-2-ylidene platinum(II) complexes with different acetylacetonate ligands [37].
  
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8. Figure 7: Neutral platinum(II) complexes 13–15 bearing azolate ligands [13].
  
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9. Figure 8: Chemical structure of neutral platinum(II) complexes 16–18 bearing azine-pyrazolato bidentate ligan...
  
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10. Figure 9: Molecular structure of carbene-containing cyclometallated alkynylplatinum(II) complexes 19–21 [41].
  
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11. Figure 10: Chemical structure of platinum(II) complexes 22a–d bearing asymmetric C^N^N tridentate ligands [53].
  
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12. Figure 11: Chemical structure of platinum(II) complexes 23 bearing bis-cyclometalating 2,6-dipyridylbenzene ty...
  
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13. Figure 12: Molecular structure of dendritic carbazole-containing alkynyl-platinum(II) complexes 24a–d [62].
  
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14. Figure 13: Molecular structure of bipolar alkynyl-platinum(II) complexes 25 bearing carbazole and electron-acc...
  
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15. Figure 14: Molecular structures of neutral platinum(II) complexes comprising donor-acceptor alkynyls (26) or e...
  
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16. Figure 15: Chemical structure of the asymmetric Pt(II) derivatives 28 bearing triazole and tetrazole moieties ...
  
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17. Figure 16: Molecular structure of the tetradentate platinum complexes 29–32 bearing N^C^C^N and C^C^C^N ligand...
  
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18. Figure 17: Chemical structure of the tetradentate Pt complexes 33–38 based on N^C^C^N-type of ligands [80-84].
  
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19. Figure 18: Chemical structure of the macrocyclic tetradentate platinum complexes reported by Wang and co-worke...
  
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20. Figure 19: Molecular structure of complex 41–46 [88,89].
  
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21. Figure 20: Molecular structure of asymmetric derivatives 47–49 based on triaryl-type of bridge [90].
  
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22. Figure 21: Chemical structure of the asymmetric tetradentate derivatives 50 and 51 based on spirofluorene link...
  
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23. Figure 22: Molecular structure of the pyridylazolate-based complexes 52–54 reported by Chi and co-workers [97].
  
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24. Figure 23: Chemical structure of the red-to-NIR emitting complexes 55–57 bearing donor–acceptor triphenylamino...
  
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25. Figure 24: Molecular structures of the Pt(IV) derivatives 58 and 59 employed as triplet emitters in solution-p...
  
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Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

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Synthesis of trifluoromethylated 2H-azirines through Togni reagent-mediated trifluoromethylation followed by PhIO-mediated azirination

Jiyun Sun,
Xiaohua Zhen,
Huaibin Ge,
Guangtao Zhang,
Xuechan An and
Yunfei Du

Full Research Paper
Published 15 Jun 2018

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1. Graphical Abstract
2. Figure 1: Representative pharmaceutical agents bearing the CF₃ group.
  
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3. Figure 2: The structures of the Togni reagents 1-(trifluoromethyl)-1,2-benziodoxol-3(1H)-one (1) and trifluor...
  
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4. Scheme 1: Our previous hypervalent iodine-mediated synthesis of 2H-azirine compounds.
  
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5. Scheme 2: Study on the presumed Togni reagent 1-mediated trifluoromethylation followed by PhIO-mediated aziri...
  
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6. Scheme 3: Togni reagent/PhIO-mediated one-pot synthesis of β-trifluoromethyl 2H-azirines. Reaction conditions...
  
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7. Scheme 4: Control study with TEMPO.
  
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8. Scheme 5: Proposed mechanism for the Togni reagent-mediated trifluoromethylation of enamines.
  
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Beilstein J. Org. Chem. 2018, 14, 1452–1458, doi:10.3762/bjoc.14.123

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Two new 2-alkylquinolones, inhibitory to the fish skin ulcer pathogen Tenacibaculum maritimum, produced by a rhizobacterium of the genus Burkholderia sp.

Dandan Li,
Naoya Oku,
Atsumi Hasada,
Masafumi Shimizu and
Yasuhiro Igarashi

Letter
Published 14 Jun 2018

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1. Graphical Abstract
2. Figure 1: Structures of compounds 1–8.
  
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3. Figure 2: Key COSY (bold line) and HMBC (arrow) correlations for 3.
  
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4. Figure 3: Referential ¹³C chemical shifts of an allylic carbon in burkholone [14] and haplacutine F [15].
  
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Beilstein J. Org. Chem. 2018, 14, 1446–1451, doi:10.3762/bjoc.14.122

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Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

Jonas Weidner,
Stefan Barwe,
Kirill Sliozberg,
Stefan Piontek,
Justus Masa,
Ulf-Peter Apfel and
Wolfgang Schuhmann

Full Research Paper
Published 13 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Conventional water electrolyzer (a) and electrolyzer using an alternative anode reaction (b) in alk...
  
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3. Figure 1: XRD patterns of Co₂Si, CoTe, CoAs. Cobalt is indicated by (+) and signals corresponding to the desi...
  
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4. Figure 2: Linear sweep voltammograms of CoP, CoB, CoTe, Co₂Si, CoAs modified and blank Ni RDEs for the OER (a...
  
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5. Figure 3: SEM micrographs of bare (a, b) and CoB-modified (c, d) NF with 1000× or 20000× magnification, respe...
  
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6. Figure 4: a) Reaction pathways of HMF oxidation; b) chromatograms at various times during constant potential ...
  
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7. Figure 5: Concentration vs time curve for HMF, HMFCA, DFF, FFCA and FDCA (a); bar diagram of the faradaic eff...
  
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Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

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Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

Dennis Hiltrop,
Steffen Cychy,
Karina Elumeeva,
Wolfgang Schuhmann and
Martin Muhler

Letter
Published 12 Jun 2018

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1. Graphical Abstract
2. Figure 1: CVs of the electrooxidation of 1 M glycerol over Pd/NCNT and Pd/OCNT in 1 M KOH at 1000 rpm at a sc...
  
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3. Figure 2: CVs of the electrooxidation of 1 M glycerol over Pd/NCNT-NH₃ and Pd/OCNT-He in 1 M NaOH at 1000 rpm...
  
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4. Figure 3: Comparison of IR spectra recorded at 0.77 and 1.17 V vs RHE (further potentials are shown in Supporting Information File 1, Figu...
  
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Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

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Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

Ruipeng Li,
Zhenren Liu,
Liang Chen,
Jing Pan and
Weicheng Zhou

Full Research Paper
Published 11 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Synthesis of dezocine by resolution.
  
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3. Scheme 2: Synthesis of catalysts C1–C17.
  
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4. Scheme 3: The proposed catalytic mechanism of stereoselective alkylation.
  
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Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

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Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

Kimihiro Komeyama,
Shunsuke Sakiyama,
Kento Iwashita,
Itaru Osaka and
Ken Takaki

Full Research Paper
Published 11 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Nucleophilic and π-electrophilic characters of organometallics depending on the central metals.
  
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3. Scheme 2: Ni/Cr or Co/Cr-catalyzed NHK reaction.
  
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4. Scheme 3: Functionalization of alkynes via carbocobaltation.
  
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5. Scheme 4: Cyclization/borylation of alkynyl iodoarenes using the Co/Cr catalyst.
  
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6. Scheme 5: Three-component coupling of aryl iodides, arenes, and aldehydes using Co/Cr catalyst (this work).
  
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7. Scheme 6: Screening of aldehydes in the Co/Cr-catalyzed three-component coupling reaction. All yields are det...
  
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8. Scheme 7: Screening of aryl iodides in the Co/Cr-catalyzed three-component coupling reaction. All yields are ...
  
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9. Scheme 8: Screening of allenes in the Co/Cr-catalyzed three-component coupling reaction. All yields are deter...
  
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10. Scheme 9: Reversed diastereoselectivity using allenyl ethers 5 and 6. ^a4-chlorobenzaldehyde was used instead ...
  
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11. Scheme 10: Stoichiometric reaction of phenylchromium(II or III) reagents (reaction 1) and the three-component ...
  
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12. Scheme 11: The origin of the diastereoselectivity in the present three-component coupling.
  
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13. Scheme 12: Plausible reaction mechanism of the three-component coupling.
  
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Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

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Recent applications of chiral calixarenes in asymmetric catalysis

Mustafa Durmaz,
Erkan Halay and
Selahattin Bozkurt

Review
Published 08 Jun 2018

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1. Graphical Abstract
2. Figure 1: Inherently chiral calix[4]arene-based phase-transfer catalysts.
  
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3. Scheme 1: Asymmetric alkylations of 3 catalyzed by (±)-1 and (±)-2 under phase-transfer conditions.
  
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4. Scheme 2: Synthesis of chiral calix[4]arene-based phase-transfer catalyst 7 and structure of O’Donnell’s N-be...
  
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5. Scheme 3: Asymmetric alkylation of glycine derivative 3 catalyzed by calixarene-based phase-transfer catalyst ...
  
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6. Figure 2: Calix[4]arene-amides used as phase-transfer catalysts.
  
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7. Scheme 4: Phase-transfer alkylation of 3 catalyzed by calixarene-triamide 12.
  
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8. Scheme 5: Synthesis of inherently chiral calix[4]arenes 20a/20b substituted at the lower rim. Reaction condit...
  
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9. Scheme 6: Asymmetric Henry reaction between 21 and 22 catalyzed by 20a/20b.
  
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10. Figure 3: Proposed transition state model of asymmetric Henry reaction.
  
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11. Scheme 7: Synthesis of enantiomerically pure phosphinoferrocenyl-substituted calixarene ligands 27–29.
  
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12. Scheme 8: Asymmetric coupling reaction of aryl boronates and aryl halides in the presence of calixarene mono ...
  
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13. Scheme 9: Asymmetric allylic alkylation in the presence of calix[4]arene ligand (S,S)-29.
  
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14. Figure 4: Structure of inherently chiral oxazoline calix[4]arenes applied in the palladium-catalyzed Tsuji–Tr...
  
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15. Scheme 10: Asymmetric Tsuji–Trost reaction in the presence of calix[4]arene ligands 36–39.
  
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16. Figure 5: BINOL-derived calix[4]arene-diphosphite ligands.
  
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17. Scheme 11: Asymmetric hydrogenation of 41a and 41b catalyzed by in situ-generated catalysts comprised of [Rh(C...
  
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18. Figure 6: Inherently chiral calix[4]arene 43 containing a diarylmethanol structure.
  
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19. Scheme 12: Asymmetric Michael addition reaction of 44 with 45 catalyzed by 43.
  
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20. Figure 7: Calix[4]arene-based chiral primary amine–thiourea catalysts.
  
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21. Scheme 13: Asymmetric Michael addition of 48 with 49 catalyzed by 47a and 47b.
  
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22. Scheme 14: Enantioselective Michael addition of 51 to 52 catalyzed by calix[4]arene thioureas.
  
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23. Scheme 15: Synthesis of calix[4]arene-based tertiary amine–thioureas 54–56.
  
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24. Scheme 16: Asymmetric Michael addition of 34 and 57 to nitroalkenes 49 catalyzed by 54b.
  
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25. Scheme 17: Synthesis of p-tert-butylcalix[4]arene bis-squaramide derivative 64.
  
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26. Scheme 18: Asymmetric Michael addition catalyzed by 64.
  
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27. Scheme 19: Synthesis of chiral p-tert-butylphenol analogue 68.
  
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28. Figure 8: Novel prolinamide organocatalysts based on the calix[4]arene scaffold.
  
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29. Scheme 20: Asymmetric aldol reactions of 72 with 70 and 71 catalyzed by 69b.
  
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30. Scheme 21: Synthesis of p-tert-butylcalix[4]arene-based chiral organocatalysts 75 and 78 derived from L-prolin...
  
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31. Scheme 22: Synthesis of upper rim-functionalized calix[4]arene-based L-proline derivative 83.
  
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32. Scheme 23: Synthesis and proposed structure of Calix-Pro-MN (86).
  
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33. Figure 9: Calix[4]arene-based L-proline catalysts containing ester, amide and acid units.
  
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34. Scheme 24: Synthesis of calix[4]arene-based prolinamide 92.
  
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35. Scheme 25: Calixarene-based catalysts for the aldol reaction of 21 with 70.
  
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36. Scheme 26: Asymmetric aldol reactions of 72 with cyclic ketones catalyzed by calix[4]arene-based chiral organo...
  
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37. Figure 10: A proposed structure for catalyst 92 in H₂O.
  
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38. Scheme 27: Synthetic route for organocatalyst 98.
  
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39. Scheme 28: Asymmetric aldol reactions catalyzed by 99.
  
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40. Figure 11: Proposed catalytic environment for catalyst 99 in the presence of water.
  
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41. Scheme 29: Asymmetric aldol reactions between 94 and 72 catalyzed by 55a.
  
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42. Scheme 30: Enantioselective Biginelli reactions catalyzed by 69f.
  
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43. Scheme 31: Synthesis of calix[4]arene–(salen) complexes.
  
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44. Scheme 32: Enantioselective epoxidation of 108 catalyzed by 107a/107b.
  
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45. Scheme 33: Synthesis of inherently chiral calix[4]arene catalysts 111 and 112.
  
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46. Scheme 34: Enantioselective MPV reduction.
  
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47. Scheme 35: Synthesis of chiral calix[4]arene ligands 116a–c.
  
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48. Scheme 36: Asymmetric MPV reduction with chiral calix[4]arene ligands.
  
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49. Scheme 37: Chiral Al^III–calixarene complexes bearing distally positioned chiral substituents.
  
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50. Scheme 38: Asymmetric MPV reduction in the presence of chiral calix[4]arene diphosphites.
  
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51. Scheme 39: Synthesis of enantiomerically pure inherently chiral calix[4]arene phosphonic acid.
  
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52. Scheme 40: Asymmetric aza-Diels–Alder reactions catalyzed by (cR,pR)-121.
  
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53. Scheme 41: Asymmetric ring opening of epoxides catalyzed by (cR,pR)-121.
  
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Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

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Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions

Anja Gronewold,
Mareike Horn and
Ines Neundorf

Full Research Paper
Published 07 Jun 2018

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1. Graphical Abstract
2. Figure 1: Circular dichroism spectra of the novel peptides solved in 10 mM phosphate buffer (pH 7) (A), or ph...
  
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3. Figure 2: Cytotoxicity profiles of the peptides in MCF-7 and HeLa cells. Cells were incubated for 24 h with d...
  
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4. Figure 3: Cellular uptake in HeLa and MCF-7 cells. Cells were incubated for 30 min with 10 µM of CF-labeled p...
  
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5. Figure 4: Cellular uptake in MCF-7 and HeLa cells was quantified by flow cytometry. Cells were incubated with...
  
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6. Figure 5: Distribution pattern of the peptides in HeLa and MCF-7 cells when incubating 10 µM CF-labeled pepti...
  
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7. Figure 6: Cellular uptake in HeLa and MCF-7 cells when incubating the cells at 4 °C for 30 min with the CF-la...
  
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8. Figure 7: Uptake and delivery of DOX into HeLa and MCF-7 cells. Fluorescence microscopic images after 30 min ...
  
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Beilstein J. Org. Chem. 2018, 14, 1378–1388, doi:10.3762/bjoc.14.116

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A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds

Claudia Lar,
Adrian Woiczechowski-Pop,
Attila Bende,
Ioana Georgeta Grosu,
Natalia Miklášová,
Elena Bogdan,
Niculina Daniela Hădade,
Anamaria Terec and
Ion Grosu

Full Research Paper
Published 06 Jun 2018

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1. Graphical Abstract
2. Figure 1: Cryptands with 1,3,5-triphenylbenzene (1) and 2,4,6-triphenyl-1,3,5-triazine (2) aromatic reference...
  
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3. Scheme 1: Synthesis of cryptand 2.
  
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4. Figure 2: NMR spectra of cryptand 2: top, ¹H NMR; bottom, ¹³C NMR.
  
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5. Figure 3: Chemical shift changes of the reference signal (belonging to the more deshielded protons of the p-p...
  
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6. Figure 4: The equilibrium geometry structure of cryptand 2 having 2,4,6-triphenyl-1,3,5-triazine caps.
  
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7. Figure 5: The equilibrium geometry structures of the cryptand–anthracene (a) and cryptand–pyrene (b) host–gue...
  
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8. Figure 6: The equilibrium geometry structure of the cryptand 2–1,5-dihydroxynaphthalene host–guest complex.
  
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9. Figure 7: The inclusion dynamics of the anthracene in the cavity of the cryptand for different constrained di...
  
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Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115

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Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

Hélène Pellissier

Review
Published 06 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Mannich reaction of N-Boc-isatin imines with ethyl nitroacetate (2) catalyzed by a cinchona alkaloi...
  
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3. Scheme 2: Mannich reaction of N-Boc-isatin imines with 1,3-dicarbonyl compounds catalyzed by a cinchona alkal...
  
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4. Scheme 3: Mannich reaction of N-alkoxycarbonylisatin imines with acetylacetone catalyzed by a cinchona alkalo...
  
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5. Scheme 4: Mannich reaction of isatin-derived benzhydrylketimines with trimethylsiloxyfuran catalyzed by a pho...
  
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6. Scheme 5: Mannich reaction of N-Boc-isatin imines with acetaldehyde catalyzed by a primary amine.
  
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7. Scheme 6: Mannich reaction of N-Cbz-isatin imines with aldehydes catalyzed by L-diphenylprolinol trimethylsil...
  
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8. Scheme 7: Addition of dimedone-derived enaminones to N-Boc-isatin imines catalyzed by a phosphoric acid.
  
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9. Scheme 8: Addition of hydroxyfuran-2-one-derived enaminones to N-Boc-isatin imines catalyzed by a phosphoric ...
  
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10. Scheme 9: Zinc-catalyzed Mannich reaction of N-Boc-isatin imines with silyl ketene imines.
  
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11. Scheme 10: Tin-catalyzed Mannich reaction of N-arylisatin imines with an alkenyl trichloroacetate.
  
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12. Scheme 11: Aza-Morita–Baylis–Hillman reaction of N-Boc-isatin imines with acrolein catalyzed by β-isocupreidin...
  
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13. Scheme 12: Aza-Morita–Baylis–Hillman reaction of N-Boc-isatin imines with acrolein (35) catalyzed by α-isocupr...
  
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14. Scheme 13: Aza-Morita–Baylis–Hillman reaction of N-Boc-isatin imines with maleimides catalyzed by β-isocupreid...
  
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15. Scheme 14: Aza-Morita–Baylis–Hillman reaction of N-Boc-isatin imines with nitroolefins catalyzed by a cinchona...
  
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16. Scheme 15: Friedel–Crafts reactions of N-Boc-isatin imines with 1 and 2-naphthols catalyzed by a cinchona alka...
  
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17. Scheme 16: Friedel–Crafts reactions of N-alkoxycarbonyl-isatin imines with 1 and 2-naphthols catalyzed by a ci...
  
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18. Scheme 17: Friedel–Crafts reaction of N-Boc-isatin imines with 6-hydroxyquinolines catalyzed by a cinchona alk...
  
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19. Scheme 18: Aza-Henry reaction of N-Boc-isatin imines with nitromethane catalyzed by a bifunctional guanidine.
  
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20. Scheme 19: Domino addition/cyclization reaction of N-Boc-isatin imines with 1,4-dithiane-2,5-diol (53) catalyz...
  
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21. Scheme 20: Nickel-catalyzed additions of methanol and cumene hydroperoxide to N-Boc-isatin imines.
  
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22. Scheme 21: Palladium-catalyzed addition of arylboronic acids to N-tert-butylsulfonylisatin imines.
  
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Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

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[3 + 2]-Cycloaddition reaction of sydnones with alkynes

Veronika Hladíková,
Jiří Váňa and
Jiří Hanusek

Review
Published 05 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Thermal reaction of sydnones with symmetrical alkynes.
  
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3. Scheme 2: Reaction of sydnones with strained cycloalkynes.
  
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4. Scheme 3: Reaction of sydnones with didehydrobenzenes.
  
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5. Scheme 4: Formation of isomeric pyrazole dicarboxylates.
  
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6. Scheme 5: Mechanism of thermal cycloaddition between sydnones and alkynes.
  
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7. Scheme 6: Mechanism of photochemical reaction of sydnones with symmetrical alkynes.
  
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8. Scheme 7: HOMO–LUMO diagram for thermal [3 + 2]-cycloaddition of sydnones with alkynes.
  
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9. Scheme 8: Synthetic strategy leading to 1,2-disubstituted pyrazoles.
  
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10. Scheme 9: Unsuccessful reaction with phenylpropiolic acid.
  
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11. Scheme 10: Synthetic strategy leading to 1,4,5-trisubstituted pyrazoles.
  
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12. Scheme 11: Reaction of sydnones carrying in position 4- six-membered 2-N-heterocyclic ring.
  
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13. Scheme 12: Strain-promoted sydnone alkyne cycloaddition (SPSAC).
  
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14. Scheme 13: Synthesis of a key intermediate of niraparib.
  
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15. Scheme 14: Reaction of sydnones with 1,3-/1,4-benzdiyne equivalents.
  
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16. Scheme 15: Reaction of sydnones with heterocyclic strained cycloalkynes.
  
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17. Scheme 16: Mono-copper catalyzed cycloaddition reaction.
  
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18. Scheme 17: Di-copper catalyzed cycloaddition reaction.
  
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Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

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Acyl-group specificity of AHL synthases involved in quorum-sensing in Roseobacter group bacteria

Lisa Ziesche,
Jan Rinkel,
Jeroen S. Dickschat and
Stefan Schulz

Full Research Paper
Published 05 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Biosynthesis of AHLs by ACP-dependent LuxI type enzymes.
  
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3. Figure 1: Total ion chromatograms of the FAME extracts of A) P. inhibens 2.10, B) P. inhibens DSM17395, C) P....
  
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4. Scheme 2: Synthesis of N-pantothenoylcysteamine thioesters (PCEs) for feeding experiments with AHL synthases.
  
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5. Figure 2: Total ion chromatograms of the extracts from competition experiments using recombinant PgaI₂ from P...
  
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Beilstein J. Org. Chem. 2018, 14, 1309–1316, doi:10.3762/bjoc.14.112

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Oligonucleotide analogues with cationic backbone linkages

Melissa Meng and
Christian Ducho

Review
Published 04 Jun 2018

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1. Graphical Abstract
2. Figure 1: Biological action of single-stranded oligonucleotides (ON): antigene and antisense pathways.
  
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3. Figure 2: Selected examples 1–6 of nucleic acid modifications based on additionally attached positively charg...
  
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4. Figure 3: Oligonucleotide analogues with artificial cationic backbone linkages discussed in this review: amin...
  
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5. Scheme 1: Structure of Letsinger's modified deoxyadenosyl dinucleotide 11 and synthesis of cationic oligonucl...
  
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6. Figure 4: Artificial cationic backbone linkages 19 and 20 which are structurally related to aminoalkylated ph...
  
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7. Scheme 2: Bruice's synthesis of guanidinium-linked DNG oligomer 29 in the 5'→3' direction (Troc = 2,2,2-trich...
  
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8. Scheme 3: Bruice's synthesis of purine-containing guanidinium-linked DNG oligomer 36 in the 3'→5' direction (...
  
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9. Scheme 4: Bruice's synthesis of S-methylthiourea-linked DNmt oligomer 43.
  
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10. Figure 5: Structure of the natural product muraymycin A1 (44) and design concept of nucleosyl amino acid (NAA...
  
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11. Scheme 5: Retrosynthetic summary of Ducho's synthesis of partially zwitterionic NAA-modified oligonucleotides ...
  
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12. Scheme 6: Retrosynthetic summary of Ducho's and Grossmann's synthesis of fully cationic NAA-modified oligonuc...
  
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Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

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An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones

Gernot A. Eller,
Gytė Vilkauskaitė,
Algirdas Šačkus,
Vytas Martynaitis,
Ashenafi Damtew Mamuye,
Vittorio Pace and
Wolfgang Holzer

Full Research Paper
Published 04 Jun 2018

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1. Graphical Abstract
2. Scheme 1: Envisaged approach for the synthesis of 5-chloropyrazole-4-carboxylates 2.
  
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3. Scheme 2: Synthesis of bipyrazolone 3a.
  
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4. Figure 1: Signal of the OCH₂ ester protons of reaction product 3a (500 MHz, CDCl₃).
  
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5. Figure 2: ORTEP-plot of the crystal structure of compound 3a drawn with 50% displacement ellipsoids [(4S,4'S)-...
  
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6. Figure 3: Arrangement (4R,4'R)- and (4S,4'S)-3a enantiomers in the crystal unit drawn with 50% displacement e...
  
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7. Scheme 3: Synthesis of compounds 3a–i.
  
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8. Scheme 4: Reaction of different 5-hydroxypyrazoles with thionyl chloride.
  
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9. Scheme 5: Reaction of 1a with sulfuryl chloride.
  
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10. Scheme 6: Possible reaction mechanism for the transformation 1 → 3.
  
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11. Scheme 7: Preparation of bipyrazoles 10.
  
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12. Figure 4: ¹H NMR (italics), ¹³C NMR (normal letters) and ¹⁵N NMR (in bold) chemical shifts of 3a (in CDCl₃).
  
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Beilstein J. Org. Chem. 2018, 14, 1287–1292, doi:10.3762/bjoc.14.110

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Novel unit B cryptophycin analogues as payloads for targeted therapy

Eduard Figueras,
Adina Borbély,
Mohamed Ismail,
Marcel Frese and
Norbert Sewald

Full Research Paper
Published 01 Jun 2018

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1. Graphical Abstract
2. Figure 1: Cryptophycin-1 (1) and -52 (2).
  
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3. Scheme 1: Synthesis of modified unit B (13 and 14). Reagents and conditions: (a) 1) TsCl, DMAP, Et₃N, CH₂Cl₂,...
  
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4. Scheme 2: Synthesis of cryptophycin analogues 22, 23 and 24. Reagents and conditions: (a) 4-DMAP, 2,4,6-trich...
  
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5. Figure 2: Binding mode of 2, showing the interaction to the vinca domain peptide binding pocket (blue). Hydro...
  
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6. Figure 3: Docking of 22 to the vinca domain of β-tubulin. Surface and backbone of β-tubulin are shown in blue...
  
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7. Figure 4: Docking of 24 to β-tubulin. Surface and backbone of β-tubulin are shown in blue, GDP in yellow. H-b...
  
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Beilstein J. Org. Chem. 2018, 14, 1281–1286, doi:10.3762/bjoc.14.109

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Atom-economical group-transfer reactions with hypervalent iodine compounds

Andreas Boelke,
Peter Finkbeiner and
Boris J. Nachtsheim

Review
Published 30 May 2018

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1. Graphical Abstract
2. Scheme 1: Overview of different types of iodane-based group-transfer reactions and their atom economy based o...
  
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3. Scheme 2: (a) Structure of diaryliodonium salts 1. (b) Diarylation of a suitable substrate A with one equival...
  
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4. Scheme 3: Synthesis of biphenyls 3 and 3’ with symmetrical diaryliodonium salts 1.
  
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5. Scheme 4: Synthesis of diaryl thioethers 5.
  
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6. Scheme 5: Synthesis of two distinct S-aryl dithiocarbamates 7 and 7’ from one equivalent of diaryliodonium sa...
  
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7. Scheme 6: Synthesis of substituted isoindolin-1-ones 9 from 2-formylbenzonitrile 8 and the postulated reactio...
  
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8. Scheme 7: Domino C-/N-arylation of indoles 10.
  
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9. Scheme 8: Domino modification of N-heterocycles 12 via in situ-generated directing groups.
  
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10. Scheme 9: Synthesis of triarylamines 17 through a double arylation of anilines.
  
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11. Scheme 10: Selective conversion of novel aryl(imidazolyl)iodonium salts 1b to 1,5-disubstituted imidazoles 18.
  
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12. Scheme 11: Selected examples for the application of cyclic diaryliodonium salts 19.
  
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13. Scheme 12: Tandem oxidation–arylation sequence with (dicarboxyiodo)benzenes 20.
  
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14. Scheme 13: Oxidative α-arylation via the transfer of an intact 2-iodoaryl group.
  
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15. Scheme 14: Tandem ortho-iodination/O-arylation cascade with PIDA derivatives 20b.
  
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16. Scheme 15: Synthesis of meta-N,N-diarylaminophenols 28 and the postulated mechanism.
  
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17. Scheme 16: (Dicarboxyiodo)benzene-mediated metal-catalysed C–H amination and arylation.
  
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18. Scheme 17: Postulated mechanism for the amination–arylation sequence.
  
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19. Scheme 18: Auto-amination and cross-coupling of PIDA derivatives 20c.
  
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20. Scheme 19: Tandem C(sp³)–H olefination/C(sp²)–H arylation.
  
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21. Scheme 20: Atom efficient functionalisations with benziodoxolones 36.
  
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22. Scheme 21: Atom-efficient synthesis of furans 39 from benziodoxolones 36a and their further derivatisations.
  
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23. Scheme 22: Oxyalkynylation of diazo compounds 42.
  
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24. Scheme 23: Enantioselective oxyalkynylation of diazo compounds 42’.
  
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25. Scheme 24: Iron-catalysed oxyazidation of enamides 45.
  
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Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

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A survey of chiral hypervalent iodine reagents in asymmetric synthesis

Soumen Ghosh,
Suman Pradhan and
Indranil Chatterjee

Review
Published 30 May 2018

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1. Graphical Abstract
2. Scheme 1: An overview of different chiral iodine reagents or precursors thereof.
  
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3. Scheme 2: Asymmetric oxidation of sulfides by chiral hypervalent iodine reagents.
  
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4. Scheme 3: Oxidative dearomatization of naphthol derivatives by Kita et al.
  
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5. Scheme 4: [4 + 2] Diels–Alder dimerization reported by Birman et al.
  
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6. Scheme 5: m-CPBA guided catalytic oxidative naphthol dearomatization.
  
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7. Scheme 6: Oxidative dearomatization of phenolic derivatives by Ishihara et al.
  
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8. Scheme 7: Oxidative spirocyclization applying precatalyst 11 developed by Ciufolini et al.
  
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9. Scheme 8: Asymmetric hydroxylative dearomatization.
  
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10. Scheme 9: Enantioselective oxylactonization reported by Fujita et al.
  
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11. Scheme 10: Dioxytosylation of styrene (47) by Wirth et al.
  
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12. Scheme 11: Oxyarylation and aminoarylation of alkenes.
  
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13. Scheme 12: Asymmetric diamination of alkenes.
  
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14. Scheme 13: Stereoselective oxyamination of alkenes reported by Wirth et al.
  
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15. Scheme 14: Enantioselective and regioselective aminofluorination by Nevado et al.
  
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16. Scheme 15: Fluorinated difunctionalization reported by Jacobsen et al.
  
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17. Scheme 16: Aryl rearrangement reported by Wirth et al.
  
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18. Scheme 17: α-Arylation of β-ketoesters.
  
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19. Scheme 18: Asymmetric α-oxytosylation of carbonyls.
  
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20. Scheme 19: Asymmetric α-oxygenation and α-amination of carbonyls reported by Wirth et al.
  
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21. Scheme 20: Asymmetric α-functionalization of ketophenols using chiral quaternary ammonium (hypo)iodite salt re...
  
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22. Scheme 21: Oxidative Intramolecular coupling by Gong et al.
  
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23. Scheme 22: α-Sulfonyl and α-phosphoryl oxylation of ketones reported by Masson et al.
  
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24. Scheme 23: α-Fluorination of β-keto esters.
  
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25. Scheme 24: Alkynylation of β-ketoesters and amides catalyzed by phase-transfer catalyst.
  
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26. Scheme 25: Alkynylation of β-ketoesters and dearomative alkynylation of phenols.
  
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Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

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London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

Andreas H. Heindl,
Raffael C. Wende and
Hermann A. Wegner

Full Research Paper
Published 29 May 2018

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1. Graphical Abstract
2. Scheme 1: Half-lives for the thermal Z→E isomerization of all-meta-alkyl-substituted azobenzenes 1–3 in DMSO ...
  
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3. Scheme 2: Isomerization of N-substituted Z-azobenzenes (a). Rotational equilibrium of (Z)-4 allowing intramol...
  
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4. Figure 1: a) Optimized geometry of open conformer (R,S)-4 c0. b) NCI plot of the most stable conformer of (R,S...
  
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Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

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A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

Anna Czarnecka,
Emilia Kowalska,
Agnieszka Bodzioch,
Joanna Skalik,
Marek Koprowski,
Krzysztof Owsianik and
Piotr Bałczewski

Full Research Paper
Published 29 May 2018

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1. Graphical Abstract
2. Figure 1: Structures of biologically active diarylmethanes and commercially available pharmaceuticals based o...
  
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3. Scheme 1: Various synthetic approaches to diarylmethanols (literature review and this work).
  
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4. Scheme 2: A general strategy for the synthesis of ortho-1,3-dithianylaryl(aryl)methanols 5 and 6, and their r...
  
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5. Scheme 3: Attempts of the OH removal in ortho-1,3-dithianyl- 6b and ortho-1,3-dioxanylaryl(aryl)methanols 9 u...
  
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Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

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Synthesis of pyrazolopyrimidinones using a “one-pot” approach under microwave irradiation

Mark Kelada,
John M. D. Walsh,
Robert W. Devine,
Patrick McArdle and
John C. Stephens

Letter
Published 28 May 2018

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1. Graphical Abstract
2. Figure 1: Bioactive pyrazolo[1,5-a]pyrimidinones.
  
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3. Scheme 1: Synthesis of 5-aminopyrazoles. Reaction conditions: ketonitrile (2.0 mmol, 1.0 equiv), hydrazine (2...
  
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4. Scheme 2: One-pot synthesis of pyrazolo[1,5-a]pyrimidinones. ^aReaction conditions: ketonitrile (0.9 mmol, 1.0...
  
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5. Figure 2: X-ray crystal structure of pyrazolo[1,5-a]pyrimidinone 3m with ellipsoids at 50% probability.
  
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Beilstein J. Org. Chem. 2018, 14, 1222–1228, doi:10.3762/bjoc.14.104

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Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

Yue Pan,
Kunfang Jia,
Yali Chen and
Yiyun Chen

Full Research Paper
Published 28 May 2018

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1. Graphical Abstract
2. Scheme 1: Investigation of alkynylbenziodoxole derivatives for radical alkynylations.
  
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3. Scheme 2: Synthesis and characterization of BI-alkyne derivatives 3a–f.
  
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4. Scheme 3: Reaction of alkynylbenziodoxole derivatives for deboronative alkynylation in photoredox catalysis. ...
  
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5. Scheme 4: Reaction of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis. Reac...
  
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6. Scheme 5: Reaction of alkynylbenziodoxole derivatives for acyl radical alkynylation in photoredox catalysis. ...
  
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7. Scheme 6: Mechanistic investigations of alkynylbenziodoxole for radical acceptor and oxidative quenching reac...
  
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8. Scheme 7: The role of alkynylbenziodoxole derivatives for radical alkynylation in photoredox catalysis.
  
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Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

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Rhodium-catalyzed C–H functionalization of heteroarenes using indoleBX hypervalent iodine reagents

Erwann Grenet,
Ashis Das,
Paola Caramenti and
Jérôme Waser

Letter
Published 25 May 2018

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1. Graphical Abstract
2. Figure 1: Bioactive compounds with pyridinone, quinolone and indole cores.
  
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3. Scheme 1: C–H functionalization of pyridinones and quinoline N-oxides.
  
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4. Scheme 2: Scope and limitations of the Rh-catalyzed C–H activation of [1,2'-bipyridin]-2-one.
  
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5. Scheme 3: Scope of the Rh-catalyzed peri C–H activation of quinoline N-oxides.
  
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6. Scheme 4: Product modifications.
  
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Beilstein J. Org. Chem. 2018, 14, 1208–1214, doi:10.3762/bjoc.14.102

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Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

Elsa Deruer,
Vincent Hamel,
Samuel Blais and
Sylvain Canesi

Letter
Published 24 May 2018

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1. Graphical Abstract
2. Scheme 1: Mechanistic hypothesis.
  
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3. Scheme 2: Extension of the method.
  
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4. Scheme 3: Carbon-based nucleophiles.
  
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5. Scheme 4: THF ring opening.
  
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Beilstein J. Org. Chem. 2018, 14, 1203–1207, doi:10.3762/bjoc.14.101

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Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

Koichi Mitsudo,
Junya Yamamoto,
Tomoya Akagi,
Atsuhiro Yamashita,
Masahiro Haisa,
Kazuki Yoshioka,
Hiroki Mandai,
Koji Ueoka,
Christian Hempel,
Jun-ichi Yoshida and
Seiji Suga

Letter
Published 24 May 2018

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1. Graphical Abstract
2. Scheme 1: Generation and reaction of cationic species generated by “indirect cation pool” methods.
  
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3. Figure 1: (a) ¹H NMR of N-acyliminium ion C1 in CD₂Cl₂ at −80 °C (600 MHz). (b) Preferred conformation of C1.
  
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4. Figure 2: (a) ¹H NMR spectrum of C3 in CD₂Cl₂ at −60 °C (400 MHz). (b) Preferred conformation of C3.
  
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5. Figure 3: (a) ¹H NMR spectrum of C5 in CD₂Cl₂ at −60 °C (400 MHz). (b) Preferred conformation of C5.
  
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6. Figure 4: Summary of the conformations of N-acyliminium ions C1–C6.
  
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7. Figure 5: Stevens’ hypothesis on the tendency of the addition of nucleophiles to N-acyliminium ions. The subs...
  
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8. Figure 6: A plausible mechanism of the observed diastereoselective reaction of the N-acyliminium ions.
  
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9. Figure 7: Comparison of ΔG for the pseudo-equatorial and pseudo-axial conformations of C1–C6 at the B3LYP/6-3...
  
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