57093-48-8

Upstream product

• 170234-82-9 1-(4-Benzyloxy-3-methoxy-phenyl)-3-(6-hydroxy-2,4-dimethoxy-3-methoxymethoxy-phenyl)-propane-1,3-dione 
• 170234-89-6 2-(4-Benzyloxy-3-methoxy-phenyl)-5,7-dimethoxy-6-methoxymethoxy-chromen-4-one 
• 170234-71-6 3-Hydroxy-2-(4-hydroxy-3-methoxy-phenyl)-5,7-dimethoxy-6-methoxymethoxy-chromen-4-one 
• 104481-00-7 1-(6-hydroxy-2,4-dimethoxy-3-methoxymethoxyphenyl)-ethanone 
• 6962-57-8 3,6-dihydroxy-2,4-dimethoxyacetophenone 
• 170234-97-6 Acetic acid 2-(4-acetoxy-3-methoxy-phenyl)-6-hydroxy-5,7-dimethoxy-4-oxo-4H-chromen-3-yl ester 

Relevant academic research and scientific papers

Studies of the selective O-alkylation and dealkylation of flavonoids. XVIII. A convenient method for synthesizing 3,5,6,7-tetrahydroxyflavones

In the demethylation of 6-hydroxy-3,4',7-trimethoxy-5-(tosyloxy)flavone with anhydrous aluminum bromide, the 5-tosyloxyl group was eliminated with bromination to give 8-bromo-3,6,7-trihydroxy-4'-methoxyflavone as the main product. When anhydrous aluminum chloride was used in the demethylation of the acetate, the 5-tosyloxyl group was cleaved prior to the demethylation to give 5,6,7-trihydroxy-3,4'-dimethoxyflavone. Demethylation of 6-hydroxy-4',5,7-trimethoxy-3-(tosyloxy)flavone and its acetate with the bromide or chloride afforded the 5,6,7-trihydroxyflavone without the cleavage of the 3-tosyloxyl group, but was not suitable for the general synthesis of the 3,5,6,7-tetrahydroxyflavones because of the difficulty in removing the protecting group. Consequently, it was found that the direct demethylation of 3,6-dihydroxy-5,7-dimethoxyflavones with anhydrous aluminum chloride-sodium iodide in acetonitrile was the most useful general method for synthesizing 3,5,6,7-tetrahydroxyflavones. Additionally, the reported structures of two natural flavones were revised.