Novel syntheses of dihydroxanthyletin and dihydroseselin derivatives

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‐2 H ,8 H‐ 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‐2 H ,8 H ‐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.