Studies in 4-Hydroxycoumarins : Part lll y-Pyrones from 4-Hydroxycoumarins

4-Hydroxy-3-acetylcoumarin. on Claisen condensation with ethyl oxalate gave the \(\beta\)-diketone (Id) which eyclised to 4,5-dioxo-4H,5H-pyrano(3-2-c) benzopyran-2-carboxylic acid (IIb). 4-hydroxy-6- methyI-3-acetylcouma,rin, on similar condensation with ethyl benzoate and ethyl oxalate gave (IIb) and (IIc) respectively. 3 -Propionyl -4-hyd roxy- 6 -methylc oumarm and 3 - propionyl -4 -hydroxy-7 -methoxy - coumarin on Kostanecki-Robinson a,cetylation gave (IId) and (lIe) respectively