FORFARANDE FOR FRAMSTELLNING AV FUROKUMARINER

Pharmacologically valuable furocoumarins of the general formula (I) wherein R is selected from the group consisting of hydrogen, a hydroxyl group and a lower alkoxy group, are prepared by reacting a substituted coumarin of the general formula (II) wherein R has the aforesaid meaning, or an alkali metal salt thereof, with a haloacetale of the general formula (III) wherein R1 is a lower alkyl group and Hal is selected from the group consisting of chlorine and bromine, in an inert, nonaqueous organic solvent or solvent mixture, to obtain an intermediate product of the general formula (IV) wherein R and R1 have the aforesaid meanings, which is treated with a dilute acid at an elevated temperature, to obtain a compound of the general formula V wherein R has the aforesaid meaning, which is converted into the end product of the general formula I by treating with a dilute alkaline solution.