Benzofuran-2-carboxylic acid

The base-promoted ring contraction of 3-bromo-2-pyrones to 2-furoic acids cf. Scheme llOd) is a well exemplified reaction 01CB1992,69JCS(C)1950,73JCS(P1)1130> which has also been applied to the obtention of benzofuran-2-carboxylic acids frorn 3-bromocoumarins 08CB830,70KGS(S2)166), Similar base treatment of 3-amino-2-pyrones provides pyrrole-2-carboxylic acids (Scheme IlOe) 75JHC129). 

Bromo-2-pyrones and 3-bromocoumarins give furan- and benzofuran-2-carboxylic acids by ring fission and subsequent closure, e.g. (228) — (229) (116) or (117) — (230). Pyrone rings are opened by aqueous acid in some cases, probably by successive protonation and attack of a water molecule, e.g. dehydroacetic acid (231) gives (233) which immediately forms (232) or (234) with HC1 or H2S04, respectively. 

Similarly, a substituted coumarin is converted into a benzofuran-2-carboxylic acid (291), a reaction which is useful in the determination of structure (73JCS(Pl)278l). 

Diethylamino-benzofuran-2-carboxylic acid ethyl ester... 

Amongst other examples of pharmacologically active seven-membered heterocyclic ring compounds the following are of interest 5-(2-morpholin-4-yl-ethoxy)-benzofuran-2-carboxylic acid (,S)-3-methyl-1 - 3-oxo-1 -[2-(3-pyridin-2-yl-phenyl)-ethenoyl]azepan-4-... 

Benzofuran, 2-phenyl -, nitration, 58, 224 Benzofuran, 4,5,6,7-tetrafluoro-2-fluoromethyl-, 60, 28 Benzofuran-3-carboxylate, 4,5,6,7-tetrafluoro-2-methyl-, 60, 18 Benzofuran-2-carboxylic acid, esters, bromination, 59, 250... 

Bishydrazide 240 is an insecticide used to combat Lepidoptera, presumably moths <1996JPP8231528>. A series of amides of benzofuran-2-carboxylic acid were evaluated for activity against the fearsome sweet potato weevil. The... 

Selected values of the product ee, as reported by different groups, are listed in Table 10.4. The effects of the structure were not clear, but a longer alkyl chain at the P-posihon tended to provide a better ee-value. The addition of BA to the reachon mixture improved the stereoselectivity, but the effect was limited. The hydrogenahon of a family of furan-2-carboxylic acids was also reported [112] the best ee-value of 53% was obtained when benzofuran-2-carboxylic acid was hydrogenated in 2-propanol with the CD-modified Pd/Al2O3 under high-pressure condihons (30 atm). 

Dichloro-2,3-di-hydro-5-(2-thienyl-carnonyl)-benzofuran-2-carboxylic acid... 

In connection with our studies on the dimerisation of aylethanals and arylacetones with boron tribromide, we first turn to the reaction of methoxylated arylpyruvic acids [38], Arylpyruvic acids that were obtained mainly in their Z-enol form, did not dimerise. When the ortho aromatic position is unsubstituted, only an isomerisation occurs that allowed us to isolate some 2-hydroxyarylpropenoic acids in their E-form. In the cases of (2-methoxyphenyl)arylpropenoic acids, cyclisations were also observed leading of mixtures of benzofuran-2-carboxylic acids and 3-hydroxycoumarins that are easily separated, Fig. (12). We observed a competition between cyclisation and isomerisation that have apparently similar kinetic parameters. 

In the methodology of Tanaka and co-workers, o-acylphenols are treated with bromomalonate after condensation, saponification, and decarboxylation the corresponding benzofuran-2-carboxylic acids are obtained (Scheme 62) <5UA872,72JCS(Pl)556,82LA1836, 85JHC1377>. 

Phenylbenzofuran (282) was used to protect polyphenylene ether resins against damage from UV radiation <87USP4665ii2>. As a nucleating agent, benzofuran-2-carboxylic acid (283) was found to improve the properties of an ethylene/4-methyl-l-pentene copolymer <84JAP(K)59197446). 

Hydroxy-3-methyl-7-(l-oxopropyl)benzofuran-2-carboxylic acid methyl ester [35093-16-4]... 

Chloro-6-hydroxy-3 -methyl-7-(l -oxopropyl)benzofuran-2-carboxylic acid, 1998... 

Use as a Base in Condensation Reactions. Pyridine can be used as a base in cyclocondensation reactions. When the reaction of 2-acylphenoxyacetic acids in acetic anhydride is carried out in the presence of pyridine, formation of benzofuran-2-carboxylic acids is preferred. When weaker bases such as sodium acetate or sodium formate are used for the reaction, mixtures of ben-zofurans and benzofuran-2-carboxyhc acids are produced, with... 

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