Methyl 5- furan-2-carboxylate

N-Methyl formyl 2.6 difluoro benzamide lufenuron 2 Methyl furan carboxylic acid fenfuram... 

Using these assumptions and conventions, Imoto and co-workers have correlated a number of series of reactions of thiophenes and furans. The reactions studied are the acid-base equilibria pK values) and the acid catalyzed methylations (thiophenes only) of thiophene-and furan-carboxylic acids and the alkaline hydrolyses of their ethyl esters the side-chain bromination of the a-acetylthiophenes, and the a-mercuration of thiophenes and the polarographic half-wave potentials of the methyl esters of thiophene- and furan-carboxylic acids and of nitrothiophenes. The pK values were determined and the ester hydrolyses studied for all three substitution orientations in the thiophene series. For the 4-R-2-Y and 5-R-2-Y series, the p-values do not appear significantly different and the data could probably be combined into a single series unfortunately, however, no limits of accuracy are reported for the p-values, and some of the raw data are not readily available so recalculation is not easily possible. For the 5-R-3-Y series the p-values deviate considerably from the other values however, whereas they are higher for the pK values, they are lower for the ester hydrolyses, and it is possible that the differences are neither systematic nor significant. 

Methyl 2-furoate was dimethoxylated using methanol in sulfuric acid to give methyl-2,5-dihydro-2,5dimethoxy-2-furan carboxylate [70]. The reaction mechanism at the electrodes is not completely known. However, the anodic reaction is said to be the oxidation of methanol. A two-electron process is assumed and hydrogen production is observed at the cathode. 

Chlorination of furan at -40 °C with 1.6 mol of chlorine affords 2-chloro- (64%), 2,5-dichloro- (29%) and 2,3,5-trichloro-furan (7%). By use of more chlorine the addition product 2,2,3,4,5,5-hexachloro-2,5-dihydrofuran and tetrachlorofuran are obtained. The chlorination of methyl furan-2-carboxylate obeys second order kinetics, when the 5-chloro compound is the only product. 

Butylpotassium and butylcesium deprotonate furan at the 2-position (75BSF1302), but butyllithium is the reagent of choice. When furan is treated with butyllithium the reactions in Scheme 114 occur (77JCS(P1)887>. The conditions, however, may be controlled to yield predominantly the mono- or the di-lithio derivative. By carbonation and esterification of the reaction mixture obtained by treatment of furan with butyllithium and TMEDA (1 1 1) in ether at 25 °C for 30 min, a 98% yield of methyl furan-2-carboxylate is obtained. Similarly, a butyllithium TMEDA furan ratio of 2.5 2.5 1 in boiling hexane for 30 min results in 91% of dimethyl furan-2,5-dicarboxylate and 9% of the monoester. Competition experiments indicate that furan reacts with butyllithium faster than thiophene under non-ionizing conditions but that the order is reversed in ether or in the presence of TMEDA. 

The copper(l)-catalyzed asymmetric cyclopropanation of methyl furan-2-carboxylate with ethyl diazoacetate was achieved by the use of the bisoxazoline ligand 12 to provide the o o-isomer of 2-oxa[3.0.1 ]bicyclohexene 13, as shown in Scheme 5 <2003CEJ260>. The product was transformed into 1,2,3-trisubstituted cyclopropane by ozonolysis... 

RHODIUM(II) ACETATE-CATALYZED REACTION OF ACETYLENES WITH a-DIAZOCARBONYLS ETHYL 2-METHYL-5-PHENYL-3-FURAN-CARBOXYLATE... 

The rhodium- or copper-catalyzed cyclopropanation of furan and its derivatives with diazo-acetic esters,300-302 or ethyl 2-diazopropanoate300 usually leads to a mixture of the 2-oxa-bicyclo[3.1.0]hex-3-ene-e co-6-carboxylate, ring-opened (4Z)-6-oxohexa-2,4-dienoates, and ring-substituted furans. Only with electron-deficient furans methyl furan-2-carboxylates, 2-[( )-2-methoxycarbonylvinyl]furan300 and with benzofuran,301,303 was the cyclopropane product obtained exclusively. Examples 37-40 are representative.300... 

Huw M. L. Davies, William R. Cantrell, Jr., Karen R. Romines, and Jonathan S. Baum 93 SYNTHESIS OF FURANS VIA RHODIUM(II) ACETATE-CATALYZED REACTION OF ACETYLENES WITH a-DIAZOCARBONYLS ETHYL 2-METHYL-5-PHENYL-3-FURAN-CARBOXYLATE... 

Vilsmeier formylation of furans is a good route to formylfurans, though the ready availability of furfural as a starting material, and methods involving lithiated furans (section 15.4.1) are important. Formylation of substituted furans follows the rule that the strong tendency for a-substitution overrides other factors, thus both 2-methylfuran and methyl furan-3-carboxylate give the 5-aldehyde 3-methylfuran gives mainly the 2-aldehyde. ... 

An aq. soln. of KOH added in one portion at room temp, to a suspension of 2,5-dihydro-2-oxo-N-phenyl-4-[(N-phenyl-N-methyl)amino]-3-furancarboxamide in ethanol, and heated under reflux for 2 h 4,5-dihydro-4-oxo-2-phenylamino-3-furan-carboxylic acid. Y 77%. Reverse reaction s. Synth. Meth. 42, 348. F.e.s. R.A. Mack et al., Helv. Chim. Acta 71, 783-7 (1988). 

C13H1303] 3 4 0 5 C00CH2C6H5 Phot, of DTBP in the presence of corresp. 2,5-dihydro-2-methyl-furan-2-carboxylate tert-Butylbenzene 2.003(1) 2H(2,4) 1.34 H(3) 0.20 97Binl... 

The observed 100% regiochemistry of the addition of 2-methylfuran and methyl furan-2-carboxylate to all thiophene 1,1-dioxides was explained in terms of the frontier orbital theory using the calculated orbital coefficients (Scheme 93) [116]. 

Using these assumptions and conventions, Imoto and co-workers have correlated a number of series of reactions of thiophenes and furans. The reactions studied are the acid-base equilibria values) and the acid catalyzed methylations (thiophenes only) of thiophene-and furan-carboxylic acids and the alkaline hydrolyses of their ethyl esters the side-chain bromination of the a-acetylthiophenes, and the a-mercuration of thiophenes and the polarographic half-wave potentials of the methyl esters of thiophene- and furan-carboxylic acids and of nitrothiophenes. The values were determined and the... 

Gopichand et al. (407) isolated two new acyclic sesquiterpene hydrocarbons (483) and (484) from the gorgonian Plexaurella grisea as well as (-h)-a-santalene (485), which is well-known from terrestrial source. Bowden et al. (408) described new sesquiterpene furans from Sinularia capillosa and S.firma, all of which were structurally related. The furanoquinol (486) was the predominant isolate and was accompanied by the related furanoquinone (487) which may be an artifact. In addition they found the methylfurans (488-492), the furan methyl esters (493-496), and the furan carboxylic acids (497-500). A related methylfuran (501) has been obtained from the Mediterranean alcyona-cean, Alcyonum palmatum (409). 

Methyl-5-aminothia2ole-4-carboxylic acid is diazotized with isoamyl nitrite in the presence of furan in 1.2-dichloroethane to give a mixture of products 163 (53%), 164 (33%). 165 (11%), and 166 (3%) (Scheme 104) (334). This reactivity experiment was carried out to examine the possibility of the occurrence of 4,5-dehydrothiazole (hetaryne). Hetaryne intermediates seem not to be involved as an intermediate in the reaction. The formation of 163 through 166 can be rationalized in terms of the intermediacy of 166a. 

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... 

H NMR, 4, 561 <65MI31002> Benzo[b]furan-2-carboxylic acid, methyl ester UV, 4, 589 Benzo[b]furan-3-carboxylic acid, 6-chloro-4,5,7-trifluoro-2-methyl-, ethyl ester C NMR, 4, 568 <72JCS(P2)1733> Benzo[b]furan-3-carboxylic acid, 6-cyano-4,5,7-trifluoro-2-methyl-, ethyl ester C NMR, 4, 568 <72JCS(P2)1733>, 569 <72JCS(P2)1733>... 

F NMR, 4, 569 <72JCS(P2)1733> Benzo[b]furan-3-carboxylic acid, 2-methyl-, methyl ester... 

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