Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

Riccardo Innocenti,
Elena Lenci,
Gloria Menchi and
Andrea Trabocchi

Full Research Paper
Published 12 Feb 2020

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1. Graphical Abstract
2. Figure 1: Chemical structure of representative approved drugs containing a spirocyclic moiety.
  
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3. Scheme 1: Synthetic strategies for accessing pyrrolocyclopentenone derivatives, including the novel couple/pa...
  
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4. Scheme 2: Couple/pair approach using combined KA² and Pauson–Khand multicomponent reactions.
  
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5. Scheme 3: Follow-up chemistry on compound 5 taking advantage of the enone chemistry. Reaction conditions. (i)...
  
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6. Figure 2: Top: Selected NOE contacts from NOESY 1D spectra of compound 36; bottom: low energy conformer of 36...
  
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7. Figure 3: PCA plot resulting from the correlation between PC1 vs PC2, showing the positioning in the chemical...
  
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8. Figure 4: PMI plot showing the skeletal diversity of compounds 3–39 (blue diamonds) with respect to the refer...
  
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Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

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Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

Vuyisa Mzozoyana,
Fanie R. van Heerden and
Craig Grimmer

Full Research Paper
Published 10 Feb 2020

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1. Graphical Abstract
2. Scheme 1: Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin (6).
  
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3. Figure 1: ¹H NMR spectra for the “aromatic” region of coumarin 6; comparison of ¹H spectrum and ¹H-{¹⁹F} spec...
  
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4. Figure 2: ¹³C NMR spectra for coumarin 5 and 6; showing the splitting of the signal corresponding to C5.
  
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5. Figure 3: ¹⁹F,¹H-HOESY NMR spectrum for coumarin 6 illustrating two through-space interactions.
  
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6. Figure 4: Superposition of single-crystal X-ray structure (red) and DFT-optimized structure (green); RMSD 0.3...
  
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7. Figure 5: DFT-optimized structure for coumarin (6).
  
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8. Figure 6: Plots of relative energy (black trace, no units), interatomic distance F–H5 (red trace, Å), interat...
  
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9. Figure 7: Short contacts within the single-crystal X-ray structure of coumarin 6.
  
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Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

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Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

Akihiro Yuasa,
Kazunori Nagao and
Hirohisa Ohmiya

Letter
Published 07 Feb 2020

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1. Graphical Abstract
2. Scheme 1: Our strategy.
  
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3. Scheme 2: Allylic cross-coupling using aldehydes as α-alkoxyalkyl anions.
  
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4. Scheme 3: Substrate scope and reaction conditions. a) reactions were carried out with 1 (0.4 mmol), 2 (0.2 mm...
  
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5. Scheme 4: Stoichiometric reaction.
  
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6. Scheme 5: Possible pathway.
  
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Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

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The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

Itamar L. Gonçalves,
Rafaela R. da Rosa,
Vera L. Eifler-Lima and
Aloir A. Merlo

Full Research Paper
Published 06 Feb 2020

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1. Graphical Abstract
2. Scheme 1: Amines 3, 4, 8, 9, 12 and 13 installed on 5-membered isoxazoline and isoxazole rings.
  
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3. Scheme 2: Synthesis of acylisoxazolinylthioureas 17a–c and acylisoxazolylthioureas 18a–c. (i) SOCl₂, reflux, ...
  
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4. Scheme 3: Synthesis of amides. Part A: (i) SOCl₂, reflux; (ii) KOCN, acetone, reflux; (iii) amines 3, 4, 8 an...
  
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5. Figure 1: Optical textures observed on POM for thioureas 17a (a), 17b (b), 18a (c), 18b (d) and 18c (e,f). Al...
  
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6. Figure 2: Optical textures observed on POM of amide 19. (a) Fan-shaped focal conic texture of the SmA mesopha...
  
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7. Figure 3: DSC curves for the thiourea 17a (A), amide 19 (B) and 20 (C) upon the first heating and cooling cur...
  
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8. Figure 4: TGA analysis for thiourea 18c; and amides 20 and 22.
  
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Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

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Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

Jucleiton J. R. Freitas,
Queila P. S. B. Freitas,
Silvia R. C. P. Andrade,
Juliano C. R. Freitas,
Roberta A. Oliveira and
Paulo H. Menezes

Full Research Paper
Published 04 Feb 2020

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1. Graphical Abstract
2. Scheme 1: Scope of the propargylation reaction. Reactions were performed with the appropriate aldehyde (1 mmo...
  
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3. Scheme 2: Synthesis of potassium allenyltrifluoroborate (4).
  
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4. Scheme 3: Propargylation of aldehydes using potassium allenyltrifluoroborate (4).
  
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Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

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The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

Narasimhamurthy Rajeev,
Toreshettahally R. Swaroop,
Ahmad I. Alrawashdeh,
Shofiur Rahman,
Abdullah Alodhayb,
Seegehalli M. Anil,
Kuppalli R. Kiran,
Chandra,
Paris E. Georghiou,
Kanchugarakoppal S. Rangappa and
Maralinganadoddi P. Sadashiva

Full Research Paper
Published 03 Feb 2020

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1. Graphical Abstract
2. Scheme 1: Synthesis of carbamothioates from xanthate esters and benzyl isocyanides.
  
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3. Figure 1: Substrate scope for the synthesis of carbamothioates. Reaction conditions for methods A and B: sodi...
  
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4. Figure 2: ORTEP diagram of O-benzyl (4-fluorobenzyl)carbamothioate (4c).
  
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5. Figure 3: Rotamers of thionocarbamates 4 (top) and computer-minimized structures of 4c (bottom).
  
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6. Scheme 2: Proposed general reaction mechanism for the formation of carbamothioates (e.g., 4a) from xanthate e...
  
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7. Figure 4: Optimized geometries of the reactants, transition states, intermediates, and products of the propos...
  
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8. Figure 5: Relative energies of the reactants, transition states (TS1–TS3), and intermediates (Int1–Int3) of t...
  
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Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

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Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

Afef Mabrouki,
Malek Fouzai,
Armand Soldera,
Abdelkader Kriaa and
Ahmed Hedhli

Full Research Paper
Published 31 Jan 2020

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1. Graphical Abstract
2. Scheme 1: Synthesis of oxadiazole derivatives 2 and 4.
  
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3. Scheme 2: Tautomeric equilibrium of compound 3.
  
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4. Figure 1: DSC thermograms of fluorinated compounds 2b, 4a and 4b recorded at 5 °C/mn at heating (down traces)...
  
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5. Figure 2: Optical texture (×10) of liquid crystal phase for fluorinated compounds, (a): SmA phase observed in...
  
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6. Figure 3: Typical diffractogram observed for compound 2b at 398 K.
  
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7. Figure 4: Typical diffractogram observed for compound 4a at 411 K.
  
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8. Figure 5: Conformer of lowest energy of compounds: 4c, conformation A, (a) front view, (a’) top view, (a”) si...
  
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9. Figure 6: Vector of dipole moment of compounds 4c, 4b and 2b.
  
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10. Figure 7: Plot of molecular dipole moments. Orange, fluorocarbon compounds; blue, hydrocarbon compounds; gree...
  
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Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

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Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

Abhijit Paul,
Debnath Chatterjee,
Srirupa Banerjee and
Somnath Yadav

Full Research Paper
Published 29 Jan 2020

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1. Graphical Abstract
2. Figure 1: Biologically and medicinally important 3-alkenylindoles.
  
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3. Scheme 1: a) Previous and b) present work related to the synthesis of 3-alkenylindoles.
  
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4. Scheme 2: Substrate scope for the C–H alkenylation of the indoles 1. Reaction conditions: 1 (1 mmol), 2 (2 mm...
  
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5. Scheme 3: a) Three-phase test to determine a homogeneous or heterogeneous catalytic mechanism of action for t...
  
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6. Scheme 4: Probable catalytic mechanism for the transformation of 1a by the RuNC.
  
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Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

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Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

Thomas J. Cogswell,
Craig S. Donald and
Rodolfo Marquez

Full Research Paper
Published 28 Jan 2020

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1. Graphical Abstract
2. Figure 1: Aza-goniothalamin 1, (R)-(+)-goniothalamin 2 and acylated aza-goniothalamin analogue 3 [14-18].
  
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3. Scheme 1: One pot synthesis of benzyl carbamate 4 reported by Veenstra and co-workers [19].
  
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4. Scheme 2: Formation of diene 5 in 66% through a one pot, three component coupling.
  
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5. Scheme 3: Optimized conditions for the synthesis of diene 5.
  
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6. Scheme 4: Ring-closing metathesis reaction of diene 5 to yield dihydropyridone 7 [20-23].
  
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7. Figure 2: Extension of the two-pot methodology to include a variety of different aldehyde starting materials.
  
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8. Scheme 5: Total synthesis of aza-goniothalamin 1.
  
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Beilstein J. Org. Chem. 2020, 16, 135–139, doi:10.3762/bjoc.16.15

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Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

Alexander Sailer,
Franziska Ermer,
Yvonne Kraus,
Rebekkah Bingham,
Ferdinand H. Lutter,
Julia Ahlfeld and
Oliver Thorn-Seshold

Full Research Paper
Published 27 Jan 2020

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1. Graphical Abstract
2. Figure 1: a) The potent tubulin inhibitor colchicine as a lead scaffold led to the development of the HOTub g...
  
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3. Figure 2: Chemical structures of HITubs. Key variations with respect to HITub-4 are highlighted in dashed box...
  
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4. Figure 3: Photocharacterisation of HITub-4. a) Photochemical and thermal isomerisation. b) UV–vis spectra aft...
  
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5. Figure 4: a) Resazurin reduction assay for HITub-4 and nocodazole in HeLa cells (n = 3), demonstrating the di...
  
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6. Figure 5: Confocal microscopy images of immunofluorescently labelled MT networks after treatment with HITubs ...
  
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7. Figure 6: Cell cycle analysis of HITub-4-treated cells. a) and b) (Z)-HITub-4 caused significant G2/M arrest ...
  
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Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

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