In a one‐step alkylation, ring‐closure 7‐hydroxycoumarins are condensed in acid media with allyl and homoallyl halides or alcohols to linear 6,7‐dihydro‐2H,8H‐benzo[1,2–6:5,4‐b']dipyran‐2‐ones. If both carbon‐6 and carbon‐8 are unsubstituted in the original coumarin, cyclization to angular isomers 9,10‐dihydro‐2H,8H‐benzo[1,2–6:3,4‐b']dipyran‐2‐ones competes. These compounds are higher ring homologs of psoralens and angelicins commonly employed in phototherapy of skin disorders.
All Science Journal Classification (ASJC) codes
- Organic Chemistry