Studies in 3-Hydroxy Coumarins: Part II. Synthesis of 3-Hydroxy Pyrano (2, 3-h) Benzopyran and 3-Hydroxy Pyrano (3, 2-g) Benzopyran Derivatives

7-Hydroxy-8-formyl-4-methylcoumarin when condensed with aeetylglycine in presence of sodium acetate and acetic anhydride, gave 3-acetamido-8-methyl-2-6-dioxo-2H,6H-pyrano(2,3-h)benzopyran, which when refluxed with 70% sulphuric acid gave 3-amino derivative. This when treated with sodium nitrite and concentrated sulphuric acid afforded 3-hydroxy-8-methyl-2-6-dioxo-2H,6H-pyrano(2,3-h) benzopyran (Ic). 3-Hydroxy-2,6-dioxo-2H,6H-pyra,no(2,3-h) benzopyran (Id) and 4-rnethyl-7,10-dihydroxy­2,8-dioxo-2H,8H-pyrano(3,2-g) benzopyran (IIc) were similarly synthesised, from 7-hydroxy-8-formyl­coumarin and 7,8 -dihydroxy- 6 -formyl- 4 -methylcoumarin respectively.