Benzopyran

About: Benzopyran is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 15235 citations.

Electrochemical Epoxidation and Carbon - Carbon Bond Cleavage for the Preparation of 3-Methyl-4-oxo-2-phenyl-4H-1-benzopyran-8-carboxylic Acid from 3-Methyl-2-phenyl-8-(1-propenyl)-4H-1-benzopyran-4-one.

Abstract: Electrooxidative carbon–carbon bond cleavage is useful for the preparation of 3-methyl-4-oxo-2-phenyl-4H-1-benzopyran-8-carboxylic acid (1b) from 3-methyl-2-phenyl-8-(1-propenyl)-4H-1-benzopyran-4-one (2). Olefin 2 was transformed into 3-methyl-8-(1,2-epoxypropyl)-3-methyl-2-phenyl-4H-1-benzopyran-4-one (3) by the electrochemical bromohydrination in an MeCN–H2O–H2SO4–NaBr–(Pt) system followed by treatment of aqueous sodium hydroxide (94%). The epoxide 3 was electrooxidized in an MeOH–H2SO4–(C) system, affording 8-formyl-3-methyl-2-phenyl-4H-1-benzopyran-4-one (4) in 83% yield. Hydrogen peroxide oxidation of 4 in refluxing 2-butanone gave 1b in 86% yield.

Preparation technology of 7-hydroxyl-8-methyl-6-nitro-2-oxo-2H-benzopyran-3-carboxylic acid

Abstract: The invention provides a preparation technology of 7-hydroxyl-8-methyl-6-nitro-2-oxo-2H-benzopyran-3-carboxylic acid and belongs to the technical field of medicine synthesis. The 7-hydroxyl-8-methyl-6-nitro-2-oxo-2H-benzopyran-3-carboxylic acid serves as a key intermediate of a renal failure resisting drug, namely, nicousamide, 2-hydroxyl-4-methoxy-3-methylbenzaldehyde is taken as an initial material, in step 1, 2-hydroxyl-4-methoxy-3-methylbenzaldehyde is obtained after demethylation, in step 2, 2-hydroxyl-4-methoxy-3-methyl-5-nitrobenzaldehyde is obtained through a nitration reaction, in step 3, 2-hydroxyl-4-methoxy-3-methyl-5-nitrobenzaldehyde is condensed with diethyl malonate and 7-methoxy-8-methyl-6-nitro-2-oxo-2H-benzopyran-3-carboxylic acid is obtained, and in step 4, 7-hydroxyl-8-methyl-6-nitro-2-oxo-2H-benzopyran-3-carboxylic acid is obtained after demethylation.

Zinc-Induced Reduction of Ethyl 2-Cyano-3-(4-oxo-4H-1-benzopyran-3-yl)propenoates — A Medium-Dependent Reaction.

Abstract: Reduction of acrylates 1 1 with Zn in THF containing aqueous NH 4 Cl produces the cyclopentadienones 4, whereas with Zn in acetic acid reduction produces the cyanopropanoates 5.