2-Acetyl-5-methylfuran

Alkylthieno[2,3-4furans 414 and 4-alkylfuro[3,4-, ]furans 416 were obtained as unexpected side products from the reaction of 2-acetyl-5-bromothiophene and 2-acetyl-5-methylfuran with stabilized and nonstabilized ylides, along with the corresponding phosphoranes 415, pyrans 417, and dimeric products 418, respectively (Scheme 45) <2000T7573>. 

Ethanone, l-(5-methyl-2-furanyl)-, l-(5-methyl-2-furyl)ethan-l-one, 5-methyl-2-furyl methyl ketone, 2-acetyl-5-methylfuran [1193-79-9] FEMA 3609... 

Sphydrofuran and its furan derivative, secosyrins 1 and 2 and syributins 1 and 2 were synthesized from one precursor (starting from 3-tri-n-butylstannylfuran or 3-bromofuran) <97JOC6359>. Both (+)- and (-)-enantiomers of frontalin, the aggregation pheromone of the Dendroctonus pine beetles, have been synthesized from 2-acetyl-5-methylfuran <97S509>. 

Acetyl-2-(l,4-anhydro-D- T bino-tetrahydroxybutyl)-5-methylfuran (XLIII)8... 

A solution of 2.5 g. of 4-acetyl-2-(D-oroWno-tetrahydroxybutyl)-5-methylfuran in 50 ml. of 10% aqueous acetic acid is boiled for three hours and then evaporated under diminished pressure. The resulting crystals are recrystallized from acetone plus petroleum ether (b. p., 40-60°), yield, 2.2 g. m. p., 102°. 

The dialdehyde 2-(4-acetyl-5-methylfuryl-2)-diglycolaldehyde has been obtained from 4-acetyl-2-(l, 4-anhydro-D-ara ino-tetrahydroxybutyl)-5-methylfuran by a similar method. It also crystallizes with one molecule of water of crystallization.1... 

Thiamin (vitamin B-l, 177) when photolysed, gives preparations having a characteristic odour. Photolysis of an aqueous solution with a high-pressure mercury lamp is reported to give the pyrimidine (178) [ 113]. Other work used irradiation at 254 nm and concentrated on the approximately 0.1% yield of ether-soluble odoriferous products. As many as nine compounds have been identified (179), (180), (181), 2-methyl-3-formyl-4,5-dihydrofuran, 3-acetyl-4,5-dihydrofuran, 4-oxopentyl formate, 3-formyl-5-hydroxypentan-2-one, 3-mercapto-2-methyl-4,5-dihydrofuran and bis(4,5-dihydro-2-methylfuran-3-yl)disulphide [114, 115]. 

Alkenylidene cyclopropanes react readily with 246 to yield 1,4-diazo-bicyclo[3,3,0]oxtanes, whereas methylidene cyclopropane reacts only very slowly with 246 to yield a 2 + 2 cycloadduct (73AJ1553). Compound 246 also reacts with 5-methylfuran-2(3//)-one in an acyl-ene reaction to yield 7-acetyl-6,7-dihydro-2-phenyl-2.ff-pyrazolo[I,2-a]-l,2,4,-triazol-l,3, 5-trione [80JCS(P1)843]. 

Treatment of methyl vinyl ketone with sodium benzyloxide (1 esq.) followed by bromine (1 eq.) gave the expected alkoxy bromo ketone. Reaction of the latter with DBU in benzene at room temperature gave a 70% yield of 5-acetyl-3-benzyloxymethyl-2-methylfuran. 

Bromochromone reacts readily at room temperature with acetylacetone in chloroform in the presence of two equivalents of DBU. The product, isolated in 83% yield in the usual manner after quenching of the reaction mixture with 5% HC1, is 3-acetyl-5-(2-hydroxybenzoyl)-2-methylfuran. A variety of (3-diketones and P-keto esters react similarly to give moderate to excellent yields of highly functionalised trisubstituted furans. 

Partial rate factors for trifluoroacetylation at the 5-position of 2-substi-tuted furans in 1,2-dichloroethane at 75°C [Table 6.7, [72JCS(P2)71]] correlate approximately with u+ values, with p = -10. The effects of para substituents on the rate of acetylation and trifluoroacetylation of 2-aryl-5-methylfurans have been studied. In the latter reaction, the relative rates of substitution at the 3-position (to give 6.10) were H, 1.0 Cl, 0.43 Me, 5.3 and OMe, 35.4, which correlated with the Yukawa-Tsuno equation, p = -2.6, r = 0.74. For acetylation, the corresponding relative rates for... 

A large group of the furans and their derivatives have specialty and industrial uses. QO Chemicals, Inc., formerly the Chemicals Division of the Quaker Oats Company, has been the world s largest producer of furfural and its derivatives for many years. In addition to furfural, their commercial products include furfuryl alcohol, tetrahydrofuryl alcohol, tetrahydrofuran, furoic acid and its alkyl furoates, furfural amines, levulinic acid, methylfuran, acetyl furan, meth-yltetrahydrofuran, and various polyetherpolyols and resins. 

The compound was prepared by Reichstein (1930b) by acetylation of 2-methylfuran (1.2) with acetyl chloride. 

The addition of aldehydes (e.g., acetaldehyde, benzaldehyde or 3-formylfuran) to fy -furan or // -2-methylfuran complexes of the type TpRe(CO)( BuNC)( -furan) gives three dihydrofuran products (Scheme 46). The product 47 comes from anti-addition of the Lewis acid modified aldehyde to C3 of the // -furan followed by formation of a 1,3-propene dipole. Rotation around the former C3-C4 of furan positions the aldehydic oxygen for nucleophilic attack on the positive end of the dipole and hence the new furan with the acetyl group syn to the metal. This pathway... 

C8H8N2O2, 2-Amino-3-acetyl-4-cyano-5-methylfuran, 44B, 279 CsHaOs, Dimethyl 3,4-furandicarboxylate, 37B, 163... 

Onitsuka, S., Nishino, H., and Kurosawa, K., Photooxygenation of 3-acetyl-5-aryl-2-methylfurans via endoperoxide intermediate and the following reactions. Tetrahedron, 57, 6003, 2001... 

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