Dimethyl 2,5-furan dicarboxylate

These compounds (e.g., 75) have also been prepared by using the Hamaguchi-Ibata methodology (97UP3). The synthesis of an annulated di-hydroxyisobenzofuran was achieved by base-catalyzed condensation of dimethyl furan-3,4-dicarboxylate with /V-methylsuccinimide (96S1180). 

Devise a procedure for synthesis of dimethyl furan-3, 4-dicarboxylate starting from furan and dimethyl acetylene dicarboxylate. 

Dimethyl furan-3, 4-dicarboxylate can be synthesised by the following steps ... 

Heating organomercurial 34 resulted in the a-ehmination of phenyl mercury bromide, generating dichlorocarbene, followed by addition of benzaldehyde to form the corresponding carbonyl ylide 35. This ylide can be intercepted with dimethyl-acetylene dicarboxylate (DMAD) to produce dihydrofuran (36), which formed furan 37 through a dehydrochlorination process in 46% yield. 

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. 

Addition of dienophiles preferentially occurs onto the heterocyclic rings of tropones [c]-fused onto furan and pyrrole [cf. 84CHEC(4)67], Furotro-pone 307a and dimethyl acetylene dicarboxylate (DMAD) give a dimerized adduct that undergoes cycloreversion at higher temperature to form monomeric adduct 527 (Scheme 138 91CB2465). The 5,7-bis(carbomethoxy)... 

The first naphtho[a]cyclopropene 68d was also obtained by that route. 3H-indazole was proposed as an intermediate in this reaction 78>. The reaction proceeds equally well from the triplet state of 7. However with acetone light capture from the sensitizer may not have been complete. A trapping of the diradical intermediate 67 to give the known indene 69 by photolysing 7 in dimethyl-acetylene-dicarboxylate (ADC) afforded only a trace of 69. However the yield of 68a was reduced to 40%. Either trapping of 67 was not effective enough or ADC may have acted as quencher. Trapping with furan or cyclopentadiene was also not effective 78a). 

The ylide (42) is formed when carbon dioxide and dimethyl acetylene-dicarboxylate react in the presence of a trialkyl phosphite (Scheme 6). The reaction of (42) with an aromatic aldehyde afforded the furan (43). ... 

The results of the photochemical reactions of dimethyl acetylene-dicarboxylate with furan,222 thiophene,18 and 1 //-pyrrole11 were found to differ widely. Furan yielded either a 1 1 or a 2 1 adduct, and thiophene yielded a sulfur-free reaction product, viz., dimethyl phthalate. These products were formed by (4 + 2)-cycloadditions, which—in the case of thiophene—was followed by extrusion of sulfur from the initial Diels-Alder adduct. 1//-pyrrole, however, reacted in a different way because a l//-azepine (195) was isolated. This product was most probably generated by (2 + 2)-cycloaddition of the acetylene to the... 

Tetrahydrofurandimethanol. THF glycol 2,5-bis(hydroxymethyl)tetrahydrofuran. C,l I tiOy mol wt 132.16. C 54.53%. H 9.15%, O 36.32% Prepd from diallyl by oxidation with perbenzoic acid in chloroform, boiling with di) sulfuric acid and hydrolyzing the reaction product with KOH soln Boeseken, Bee. Trav. Chim. 45, 838 (1926) by Raney nickel reduction of 5 -hydroxymethylfurfural or of dimethyl furan-2.5-dicarboxylate Cope, Baxter, J. Am. Chem. Soc. 77, 393 (1955). The usual form obtained is the cis form, described here. 

A number of copolyesters have also been described in the literature, combining such mixtures as the dimethyl ester of 2 and dimethyl terephthal-ate with ethylene glycol or 1,4-butanediol. The process of melt-transester-ification was employed in the reported synthesis of copolyesters from dimethyl 2,5-furan dicarboxylate, dimethyl terephthalate, ethylene glycol, and glycerol. Similarly, melt-polycondensation has produced thermally-stable... 

Mesoionic dithiolone deriv. heated with dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate in methylene chloride cycloadduct (Y 82%) refluxed in xylene 2,5-diphenylthiophene (Y 92%) and dimethyl furan-3,4-dicarbox-ylate (Y 91%). F. e., also synthesis of 6-membered heterocyclics, s. H. Matsu-kubo and H. Kato, Chem. Commun. 1975, 840 Soc. Perkin I 1976, 2565. 

The room temperature cycloaddition of olefins to furans at 15 000 atm has been reported. Prior to this work, only reactive dienophiles (maleic anhydride, dimethyl-acetylene dicarboxylate) gave good yields of adducts, but this study has shown that weaker dienophiles can be employed (Scheme 38). ... 

Jurczak has shown that cycloaddition reactions involving furan could also be catalyzed by transfer RNA under high pressure [13]. Flence, kinetin 9 reacts with maleic anhydride and dimethyl acetylene dicarboxylate (DMAD) at lOkbar showing that tRNA is a true Diels-Alderase (Scheme 2). These products are not formed at high pressure without tRNA. It seems that a conformation of tRNA induced at high pressure meets structural requirements of a transition state of Diels-Alder reaction. It provides complementarity of size and shape of both substrates and is a driving force in molecular recognition. 

Benzo[Z)]thiophene reacts with dimethyl l,2,4,5-tetrazine-3,6-dicarboxylate in a cyclo-addition-fragmentation reaction to yield (143), whereas benzo[A]furan and N- methylindole yield products (144) arising from ring opening and recyclization (76AP679). 

Furan-2,3-dicarboxylic acid, dimethyl ester UV, 4, 588 (53G340)... 

Furan-3,4-dicarboxylic acid, dimethyl ester microwave, 4, 6 7IBCJ928)... 

The ultraviolet absorption spectra of compounds II from D-glucose and XI from D-fructose show an absorption band at 250 m/j, in accordance with their furan character.9 The product of periodate oxidation (V) and the dimethyl ester of the derived dicarboxylic acid (III) absorb at 285 and 262 m/i, respectively. The anhydrides of the condensates, XXXIV, do not exhibit selective absorption in the ultraviolet region, but the product of their oxidation (XXXVI) with periodic acid shows8 a band at about 270 m/i. 

Monomers 1 and 2 were also used as comonomers with dimethyl dialkanoates and monomers containing furan rings, for the synthesis of copolyesters by bulk polycondensations, in the presence of titanium isopropoxide or tetra-butyl-1,3-dichloro-distannoxane. In general, the biodegradability of the copolyesters of 1 decreased with increasing difuran dicarboxylate content, and copolymers... 

DMAD, dimethyl 2-methyl-5-phenylfuran-3,4-dicarboxylate (410) is formed. It has t n suggested that the reaction proceeds through the betaine (407), which is transformed into the ylide (408) and so into the furan (410) (Scheme 64). By carrying out the reaction in benzene it was possible to isolate the ylide (408) and thereby substantiate the suggested mechanism. 

Sulfur tetrafluoride fluorination of the methyl group has been reported.253 Thus, the reaction with 2,5-dimethylfuran-3,4-dicarboxylic acid gives, besides the expected acid fluoride 16 and 2,5-dimethyl-3,4-bis(trifluoromethyl)furan (17a), higher fluorinated compounds, 2-(difluoro-methyl)-5-methyl-3,4-bis(trifluoromethyl)furan (17b) and 2-methyl-3,4,5-tris(trifluoromethyl)-furan (17c). Low yields are due to considerable tar formation. 

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