Studies in the Synthesis of Coumarino- α-pyrones and Furocoumarins

7-Hydroxy-3,4-dimethylroumarin has been condensed with malic acid to yield 3, 4-dimethylcoumerino­7,8-,α -pyrone, also obtained by the Perkin acatylatien of 7-hydroxy-8-formyl-3, 4-dimothylcoumarin. The structure of the formyl derivative hoe been proved by the Dakin oxidation to the known 7,8.dihydroxy-3,4- dimethylcoumarin. The latter and 5-hydroxy-3,4,7-trimetbylcoumarin on a similar condensation with malic acid provide 3,4-dimethy1-8-hpliosyeouinerine-7,6. α-pyrone and 3,4,7-trimethyloournarino-5,6- α-pyrone respectively.

7-Hydroxy-3-brome-4-methylcoumarin has been condensed with malic acid to afford 3-brome-4-methyl­eoumerino-7,8- α-pyrone, which has also been obtained on bromination of 4-methylcoumarino-7,8-α-pyrone. It has been degraded to furo-3'-merhyl-4',5'-5,6-coumarin. This is a new approach to the synthesis of furocoumarins.