[O:1]([C:8]1[CH:15]=[C:12]([CH:13]=O)[C:11]([OH:16])=[CH:10][CH:9]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(=O)([O-])[O-].[K+].[K+].[CH:23]([C:25]([CH3:27])=[O:26])=[CH2:24].O>O1CCOCC1>[C:25]([C:23]1[CH2:24][O:16][C:11]2[CH:10]=[CH:9][C:8]([O:1][C:2]3[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=3)=[CH:15][C:12]=2[CH:13]=1)(=[O:26])[CH3:27]The starting material is prepared as follows: 5-Phenoxysalicylaldehyde (6.17 g, 28.8 mmol) is dissolved in 100 ml of 1,4-dioxane and treated with potassium carbonate (7.96 g, 57.6 mmol) and methyl vinyl ketone (3.03 g, 43.2 mmol) under nitrogen. The mixture is heated at reflux for 3 hours. Water is added and three extractions with dichloromethane are carried out. The organic extracts are combined, dried (MgSO4) and evaporated. Purification by flash chromatography (silica gel, 15% EtOAc/hexane) yields 3-acetyl-6-phenoxy-2H-1-benzopyran as a solid.
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