Organocatalytic synthesis of chiral benzopyrans
2006 (English)In: Tetrahedron: Asymmetry, no 17, 1763-1767 p.Article in journal (Refereed) Published
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 a,B-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% 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.
Place, publisher, year, edition, pages
2006. no 17, 1763-1767 p.
IdentifiersURN: urn:nbn:se:uu:diva-81325DOI: doi:10.1016/j.tetasy.2006.06.028OAI: oai:DiVA.org:uu-81325DiVA: diva2:109240