Studies in the Synthesis of Coumarino-α-pyrones and Furocoumarins. Part XII : Synthesis of 4-Hydroxy-2-oxo-2H-furo (2.3-f) Benzopyran Derivatives

7-Hydroxy-8-acetylcoumarin on bromination and hydrolysis gave 6-hydroxy-7-acetylbenzofuran, which on heating with sodium and ethyl carbonate afforded 4-hydroxy-2-oxo-2H-furo (2,3-f) benzopyran (IlIa). 4-Hydroxy-7 -methyl-2oxo-2H-furo (2,3-f) benzopyran, 4-hydroxy-3, 7 -dimethyl-2-oxo-2H-furo (2,3-f) benzopyran, 6-oarbomethoxy-4-hydroxy-3,7-dlmethyl-2-oxo-2H-furo (2,3-f) benzopyran and 4-hydroxy-5,9-dimethyl-2-oxo-2H-furo (2,3-h) benzopyran were synthesised by a similar procedure from 6-hydroxy-7 -acetyl-3-methyl benzofuran, 7 -hydroxy-8-propionyl-4-methylcoumarin and 3-chloro-5-hydroxy-6- acetyl-4, 7 -dimethylcoumarin respectively.

Furo-4-hydroxycoumarin derivatives, on treatment with formalin, gave the corresponding methylene bis derivatives (IVa), (IVb) and (VIII).