Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts

Rodrigo Abonia,
Luisa F. Gutiérrez,
Braulio Insuasty,
Jairo Quiroga,
Kenneth K. Laali,
Chunqing Zhao,
Gabriela L. Borosky,
Samantha M. Horwitz and
Scott D. Bunge

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Published 12 Mar 2019

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1. Graphical Abstract
2. Scheme 1: Representative examples of tris(hetero/aryl)methanes, molecular hybrids and bis(indolyl)methanes wi...
  
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3. Scheme 2: Previous synthetic approaches for the synthesis of triarylmethane analogues in comparison to the pr...
  
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4. Scheme 3: Synthesis of the starting N-alkylindoles 1{4–10}.
  
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5. Scheme 4: General procedure for the synthesis of the starting quinoline-/quinolone aldehydes 6{1–7}.
  
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6. Scheme 5: Chemset of coumarins 7{1–4} for elaboration in the MCR experiments.
  
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7. Scheme 6: Exploratory reaction leading to isolation of products 8{1,1,1} and 9{1,1,1}.
  
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8. Figure 1: Pseudo-three-component synthesis of bisindole triads 8 employing quinoline-/quinolone-CHO 6{1–6}, c...
  
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9. Scheme 7: Chemset of further aldehydes 6{8–10} for elaboration in the MCR experiments.
  
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10. Figure 2: Three-component synthesis of tris(heteroaryl)methane triads 9. ^aThis product was obtained as an ins...
  
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11. Figure 3: Thermal ellipsoid plot (40% probability level) of the tris(heteroaryl)methane triad 9{4,7,1}.
  
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12. Figure 4: DFT-optimized structure of 9{4,7,1} triad.
  
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13. Scheme 8: Synthesis of crowed (Het¹₂Het²/Ar²)C⁺PF₆⁻ salts 10.
  
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14. Figure 5: 1D- and 2D-based NMR assignments for methylium-PF₆ salt 10{4,4,8}.
  
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15. Figure 6: 1D- and 2D-based NMR assignments for methylium-PF₆ salt 10{4,4,11}.
  
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16. Figure 7: Optimized geometry of methylium-PF₆ salts 10{4,4,8}.
  
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17. Figure 8: Optimized geometry of methylium-PF₆ salt 10{4,4,11}.
  
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Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60

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Reaction of allene esters with Selectfluor/TMSX (X = I, Br, Cl) and Selectfluor/NH₄SCN: Competing oxidative/electrophilic dihalogenation and nucleophilic/conjugate addition

A. Srinivas Reddy and
Kenneth K. Laali

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Published 16 Sep 2015

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1. Graphical Abstract
2. Scheme 1: Reaction of benzyl allenoate (1) with TMSBr with and without Selectfluor (E/Z designations, as illu...
  
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3. Scheme 2: Reaction of benzyl allenoate (1) with TMSBr with and without Selectfluor in IL solvents (E/Z design...
  
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4. Scheme 3: Reaction of benzyl allenoate (1) with TMSI and TMSCl, with and without Selectfluor (E/Z designation...
  
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5. Scheme 4: Reaction of benzyl allenoate (1) with NH₄SCN/Selectfluor in different solvents (E/Z designations, a...
  
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6. Figure 1: Allene esters synthesized for this study.
  
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7. Scheme 5: Reaction of ethyl allenoate (2) with TMSX/Selectfluor and NH₄SCN/Selectfluor (E/Z designations, as ...
  
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8. Scheme 6: Reaction of ethyl allenoate 3 with TMSX/Selectfluor and NH₄SCN/Selectfluor (E/Z designations, as il...
  
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9. Scheme 7: Reaction of benzyl allenoate 4 with TMSX (X = Br, and Cl)/Selectfluor and NH₄SCN/Selectfluor (E/Z d...
  
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10. Scheme 8: Reaction of ethyl allenoate 5 with TMSI/Selecfluor in DMF and MeCN as the solvents (E/Z designation...
  
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11. Scheme 9: Reaction of benzyl allenoate 6 with NH₄SCN in presence and absence of Selectfluor.
  
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12. Scheme 10: Influence of allenoate structure.
  
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