29043-06-9

Upstream product

• 104481-00-7 1-(6-hydroxy-2,4-dimethoxy-3-methoxymethoxyphenyl)-ethanone 
• 155721-26-9 5-(3,6-dihydroxy-2,4-dimethoxyphenyl)-3-(3,4,5-trimethoxyphenyl)isoxazole 
• 155721-19-0 2-iodo-3,5-dimethoxy-1,4-benzoquinone 
• 530-55-2 2,6-dimethoxy-p-quinone 
• 6962-57-8 3,6-dihydroxy-2,4-dimethoxyacetophenone 
• 170234-80-7 1-(6-Hydroxy-2,4-dimethoxy-3-methoxymethoxy-phenyl)-3-(3,4,5-trimethoxy-phenyl)-propane-1,3-dione 

Downstream Products

• 170234-87-4 5,7-Dimethoxy-6-methoxymethoxy-2-(3,4,5-trimethoxy-phenyl)-chromen-4-one 
• 170234-70-5 3-Hydroxy-5,7-dimethoxy-6-methoxymethoxy-2-(3,4,5-trimethoxy-phenyl)-chromen-4-one 
• 170234-59-0 3,6-Dihydroxy-5,7-dimethoxy-2-(3,4,5-trimethoxy-phenyl)-chromen-4-one 

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.

Synthesis of Flavones via Application of the Nitrile Oxide and the Stille Reactions

Hydroxylated and methoxylated benzaldehyde oximes have been chlorinated, dehydrohalogenated and cycloadded to tributylstannylacetylene to give 3-aryl-5-tributylstannylisoxazoles in good to excellent yields.The palladium-catalyzed coupling reaction, the so-called Stille reaction, of hindered and electron-rich 2-iodophenols and a 2-iodo-1,4-benzoquinone with 3-aryl-5-tributylstannyl-isoxazoles gave 3-aryl-5-(2-hydroxyaryl)isoxazoles in moderate to excellent yields.The coupling reaction was studied under various conditions and with various Pd(II) and Pd(0) complexes.Reduction of the 3,5-diarylisoxazoles with H2/Raney-Ni, hydrolysis and acid-catalyzed cyclisation gave flavones.The synthesis of 2-iodo-3,5-dimethoxy-1,4-benzoquinone is described.