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Organocatalytic synthesis of chiral benzopyrans

Govender, T ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. DOI: 10.1016/j.tetasy.2006.06.028
  3. Publisher: 2006
  4. Abstract:
  5. Benzopyrans, or chromenes, are widespread in nature and are considered to be a privileged scaffold in medicinal chemistry. Herein, we report the first organocatalyzed asymmetric synthesis of chiral benzopyrans. The benzopyran unit is constructed through a domino reaction involving an oxa-Michael attack of salicylic aldehyde derivatives onto α,β-unsaturated aldehydes, activated through iminium-ion formation with the organocatalyst, followed by an intramolecular aldol reaction and subsequent elimination of water. This overall reaction sequence provides benzopyrans with aromatic C-2 substituents in up to 60% yield and 60% enantioselectivity, while C-2 aliphatic analogues can be obtained in 90% enantiomeric excess, but with only 20% yield. The role of additives, as well as the possible racemization of the benzopyran, was also investigated. © 2006 Elsevier Ltd. All rights reserved
  6. Keywords:
  7. Aldehyde derivative ; Benzopyran derivative ; Aldol reaction ; Asymmetric synthesis ; Catalyst ; Chemical reaction ; Chemical structure ; Chirality ; Elimination reaction ; Enantiomer ; Enantioselectivity ; Molecular interaction ; Photochemistry ; Priority journal ; Racemization ; Reaction analysis ; Structure analysis
  8. Source: Tetrahedron Asymmetry ; Volume 17, Issue 12 , 2006 , Pages 1763-1767 ; 09574166 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0957416606004241