2.4- Dimethyl-3-furan carboxylic acid

Furan carboxylic acids usually decarboxylate readily, and this method is often used in the laboratory for the preparation of furans. Furan itself can be obtained in good yield from 2-furoic acid in quinoline, with a copper catalyst, while industrial methods employ the catalytic decarbonylation of furfural. Copper powder, copper oxide or copper bronze, or heavy metal oxides,22 are the best catalysts, in combination with quinoline as solvent and weak base.23-28 Dann et al,2fl decarboxylated 2,5-dimethyl-3-furoic acid in 50% yield using barium hydroxide. 3-Furoic acid, which is difficult to obtain in large quantities, is best prepared by controlled decarboxylation of the easily prepared furan tetracarboxylic acid. 

Benzo[b]furan-2-carboxylic acid, 3,6-dimethoxy-, methyl ester UV, 4, 589 <71AJC1883> Benzo[b]furan-2-carboxylic acid, 5,6-dimethyl-, methyl ester... 

Furan-2-carboxylic acid, 3,4,5-triphenyl-dimethyl ester, 4, 691 Furan-3-carboxylic acid, 2,3-dihydro-esters... 

Dimethyl acetylenedicarboxylate gave first a similar adduct (2) which then added further molecules of furan yielding (3) and subsequently (4). Between 1931 and 1940 the reactions of acetylenedi-carboxylic acid and its dimethyl ester with a number of nitrogen containing heterocyclic compounds were examined, and structures were proposed for the products. Apart from an unpublished investigation of the products from pyridine and dimethyl acetylenedicar-... 

Carboxy-4-methyl-5-pentyl-2-furanpropanoic acid (273), isolated from blood and urine, is a hitherto unknown class of metabolic compound. The structure of (273) has recently been confirmed by synthesis (80CB699). 2,4,5-Trialkyl substituted furan-3-carboxylic acids have been synthesized from acyloin and /3-ketoesters by treatment with zinc chloride. By analogy with this synthetic route, the reaction of acetoin with 3-oxoadipic acid dimethyl ester was found to yield the 2,3-dimethylfuran (274). The dimethyl ester (275) was prepared by condensation of 3-chloro-2-octanone with 3-oxoadipic acid dimethyl ester and was shown to be identical with the dimethyl ester of the natural product. 

In a disclosure regarding the use of alicyclic carboxylic acid oxycarbonylmethyl esters and their use as odorants and perfumes, a composition was described in which two furan compounds were components <2005W02005108534>. 4,5-Dimethyl-3-hydroxy-2(577)-furanone 80 and 3a,6,6,9a-tetramethyldodecahydronaphtho[2,l- ]-furan 18 were present in <2% in the described perfume. In another fragrance-related application, compound 18 was a component of a perfume composition which was added to a shampoo formulation designed to enhance permeation as well as provide desired fragrant effects <2002JPP2002241238>. The fused tricyclic furan 18 was incorporated as 20% of the perfume mixture of which that was a component of the shampoo in 0.7%. 

Wannamaker W, et al. (S)-l-((S)-2- (l-(4-amino-3-chloro-phe-nyl)-methanoyl)-amino -3,3-dimethyl-butanoy l)-pyrrolidine-2-carboxylic acid ((2R,3S)-2-ethoxy-5-oxo-tetrahydro-furan-3-yl)-amide (VX—765), an orally available selective interleukin (IL)-converting enzyme/caspase-1 inhibitor, exhibits potent antiinflammatory activities by inhibiting the release of IL-lbeta and IL-18. J. Pharmacol. Exp. Ther. 2007 321 509-516. 

Difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoic acid 4,ll-bis[(2-Aminoethyl)amino]anthra[2,3-b]furan-5,10-diones 4(l-Anilino-podophyllotoxin derivatives 5-Aza-2 -deoxycytidine 5-Bromotetrandrine 5-Cyclohexylindolyl-2 -deoxyribose (non-natural nucleoside) 5 -Fluorosulfonylbenzoyl 5 -adenosine 5-Fluorouracil 5,5-Diphenylbarbituric acid 6-[(2S,4R,6E)-4-Methyl-2-(methylamino)-3-oxo-6-octenoic acid] cyclosporine D (PSC833) 6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid 6-Mercaptopurine 6-Prenylchrysin 6-Thioguanine 6,7-Dimethoxy-... 

Methyl isobutyl ketone Several phthalate esters Tetra-hydro-2,5-dimethyl-cis-furan Several esters of carboxylic acids (Ci2 Ci8)... 

Important components of hard cheeses (Gouda type) include some carboxylic acid esters (ethyl butanoate, ethyl hexanoate), as well as carboxylic acids (acetic, butyric, isobutyric, valeric, isovaleric, 2-methylbutyric and caproic acids). Cheeses manufactured using bacteria of the genus Propionibacterium (such as Emmental and Gruyere) contain propionic acid and other lower fatty acids, methyl thioacetate, some oxocarboxylic acids, various alcohols, esters (such as ethyl butanoate), lactones (such as 8-decalactone), amines and other basic compounds (also skatole in addition to aliphatic amines), alkylpyrazines (e.g. 2-sec-butyl-3-methoxypyrazine), 4-hydroxy-2,5-dimethyl-2H-furan-3-one (furaneol), 2-ethyl-4-hydroxy-5-methyl-2H-furan-3-one (homofuraneol) and a range of other compounds. 

More recently, Tada and co-workers reported the total synthesis of patulin (348) in 1994 (Scheme 7.1) (507). Starting with the condensation of acetonedicarboxylic acid dimethyl ester (353) and chloroacetaldehyde to form an appropriately 2,3-disubstituted furan 354, this was further reduced and selectively oxidized at the aromatic carbinol to deliver 3-furaldehyde 355. Dean-Stark condensation of this species in the presence of methanol gave the methyloxy furanopyran 356. Oxidative ring-opening to a carboxylate intermediate and subsequent methylation with diazomethane provided ester 357, which was lactonized and finally demethylated to deliver the natural product 348 in 7% yield over a total of eight consecutive steps. 

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