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

Full Research Paper
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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