O1C2C(=CC=CC=2)C=CC1=O.C(N(CC)CC)C.[OH:19][C:20]1[CH:29]=[C:28]2[C:23]([C:24]([CH3:31])=[CH:25][C:26](=[O:30])[O:27]2)=[CH:22][CH:21]=1.[C:32](Cl)(=[O:39])[C:33]1[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=1>C1COCC1>[C:32]([O:19][C:20]1[CH:29]=[C:28]2[C:23]([C:24]([CH3:31])=[CH:25][C:26](=[O:30])[O:27]2)=[CH:22][CH:21]=1)(=[O:39])[C:33]1[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=1The route shown in Scheme 1 exemplifies synthesis of the coumarin compounds of the present invention. Triethylamine is added to a solution of 7-hydroxy-4-methyl-chromen-2-one (i) and a benzoyl chloride (ii) in THF at room temperature. The reaction mixture is stirred at room temperature overnight and filtered. The filtrate is concentrated to afford a 7-benzoyloxy-4-methyl-coumarin (iii). A mixture of compound (iii) and finely powdered aluminum chloride is heated at 170° C. for 2 hours to afford an 8-benzoyl-7-hydroxy-4-methyl-chromen-2-one (iv). A mixture of compound (iv), 2-bromoacetophenone (v), and K2CO3 in CH3CN is refluxed overnight. The reaction mixture is filtered and the filtrate is concentrated. The residue is purified by column chromatography to afford a pure 8-benzoyl-4-methyl-9-phenyl-furo[2,3-h]chromen-2-one (vi).
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