6320-42-9

7-Hydroxy-2-methyl-4H-chromen-4-one is used in the synthesis of 2,2-Dimethyl-2H-pyranoflavonol and pyranochromone derivatives.

Step(i): 7-Acetoxy-3-acetyl-2-methylchromone β-Resacetophenone (4.A.6) (10 g，0.066 mole) is heated with fusedsodium acetate (20 g) in acetic anhydride (30 ml) for 5 hr at 170-180°(oil bath) under anhydrous conditions. The reaction mixture is pouredover crushed ice, stirred well and left overnight.The separated product isfiltered and washed with water. It is crystallised from alcohol as light yellowneedles.Yield 10 g (58.5%).M.p.127° (lit. m.p.126-27°).
step (ii) : The above 7-acetoxy-3-acetyl-2-methylchromone (1 g,0.0038 mole) isrefluxed (2 hr) with aqueous sodium carbonate solution (10%,50 ml).Theclear solution is then acidified with hydrochloric acid (1:1).The separatedproduct is filtered and washed with water. It is crystallised from alcohol asthick prismatic crystals. Yield 0.5 g (73.5%).M.p. 249-50°.(lit. m.p.254-55°).