Furan-2 -one

Furano( 1,4)naphthalenophane conformation, 4, 538 Furanonaphthalenophanes molecular structure, 4, 5 Furan-2-one, tetrahydro-reactions, 4, 656... 

C7H14O 111-71-7) see Undecylenic acid [3a/ -(3aa,4a,SP,6aa)]-4-[2-(2-heptyl-l,3-dioxolan-2-yl)ethyl]hexahydro-5-hydroxy-2//-cyclopenta[6]furan-2-one... 

Dihydro-2,5-dimethoxyfuran 824 reacts neat at 24°C with TCS 14 via the intermediate 825, the 2-trimethylsilyloxyfuran 826 (which can also be readily prepared from 5H-furan-2-one), and 827-829 to give the crystalline trimer 830 in 20% yield [21]. In the presence of aldehydes such as thiophen-2-aldehyde 831a or benzaldehyde 831b, however, 824 reacts via 832 to give the condensation products 833 a and 833 b, which are obtained in 30 and 62% yield, respectively [22, 23] (Scheme 6.11). Because it is postulated 2-trimethylsilyloxyfuran 826 is a intermedi-... 

Arylidine-furan-2-ones 439 undergo [4+2] cycloaddition with maleic anhydride 440 to give the tricyclic adducts 441 (Equation 119) <1997CHE910>. 

US patent 6,677,373, Polymorphic B form of 3-(cyclopropylmethoxy)-4-[4-(methylsulfonyl)phenyl]-5,5-dimethyl-5H-furan-2-one [96]. This invention concerns Form B of the title compound, crystallizing in the hexagonal R-3 space group, and which was characterized by its unit cell parameters. For this form, a = 18.183 A, b = 18.183 A, c = 26.950 A, a = jS = 90°, and y = 120°. The unit-cell volume was found to be 7716.5 A3, and there were 18 molecules per unit cell. 

Previous studies on various aliphatic and aromatic alkynes have evidenced that this type of furan-2-ones could also be produced in the presence of the rhodium carbonyl cluster [Rh4(CO)i2] [39-41]. Labeling experiments using D2O allowed the authors to assign the origin of the hydrogen atoms (Scheme 6). Noteworthy, dicobalt octacarbonyl follows a different catalytic... 

Nair and coworkers have described the [8 + 2] cycloaddition reactions of 2H-cyclohep-ta[fr]furan-2-ones such as 521 in several reports311. The reactions of 521 with alkenes yield azulene derivatives upon extrusion of carbon dioxide. Table 30 summarizes the results of the reactions between 521 and some 6,6-disubstituted fulvenes 522 (equation 151)311b. In the case of 6,6-dialkyl fulvenes 522a-c, the [8 + 2] cycloadducts 523 were the major adducts obtained, the Diels-Alder adducts 524 only being formed in trace amounts. 

The [8 + 2] cycloaddition reactions between substituted cyclohcpta h]furan-2-ones and enamines have been described by Kuroda and coworkers312. The cycloaddition reactions proceeded with concomitant elimination of carbon dioxide and amine. Thus, the reaction between 527 and enamine 528 afforded [8 + 2] cycloadduct 529 with good yield (equation 153)312c. 

Me2S04 or Et,S04 (17.3 mmol) is added with vigorous stirring to the TBA-tetronate (16.5 mmol) prepared by the addition of aqueous TBA-OH (0.5 M, 3.5 ml) to the appropriate tetronic acid (16.5 mmol) and evaporation to dryness under reduced pressure, in CH2C12 (70 ml). The mixture is stirred until the reaction is complete and the solvent is then evaporated. H,0 (50 ml) is added to the residue and the aqueous solution is continuously extracted with Et20 for ca. 3 h. The ethereal extract is washed with aqueous NaHCO, dried (MgS04), and evaporated to give the 4-alkoxy-5H-furan-2-one (R = H,... 

Nitrofuranes are converted into 3- (or 5-) -hydroxyimino-(3H)-furan-2-ones and 2-nitrop3UTol into 3-hydroxyimino-(3H)-pjuTol-2-one upon irradiation in acetone solution i ). Again, the results are rationalized best by assuming a nitrite intermediate. No experiments to delineate the multiphcity of the excited state responsible for this isomerization have been reported. 

Substituted-3/f-furan-2-ones, in the presence of a base catalyst, participate in a Michael reaction with electron-deficient a,/1-unsaturated ketones to afford furo[2,3-3]-4//-pyrans. The reaction sequence involves a heterocycliza-tion reaction followed by dehydration (Equation 29) <2003RJC655>. 

FIGURE 6.14 Infrared spectrum due primarily to 3-H-furan-2-one formed in the photolysis of butenedial after subtraction of bands due to CO, C02, HCHO, and HCOOH (adapted from Bierbach et al., 1994). 

Bierbach, A., I. Barnes, K. H. Becker, and E. Wiesen, Atmospheric Chemistry of Unsaturated Carbonyls Butenedial, 4-Oxo-2-pentenal, 3-Hexene-2,5-dione, Maleic Anhydride, 3//-Furan-2-one, and 5-Methyl-3/f-furan-2-one, Environ. Sci. Technol., 28, 715-729 (1994). 

Dihydro-5 -hydroxyamentoflavone 3.4- Dihydro-8-hydroxy-3,5-dimethyl-lH-2-benzopyran-l-one (-)-2,5-Dihydro-5-hydroxy-4-(4 -hydroxyphenyl]-furan- 2-one Methylmellein Hydroxybutenolide... 

Ring cleavage and decarbonylation has also been observed in benzo[h]-furan-2-one.170 Careful examination of the 3-phenyl derivative has shown that decarbonylation arises by excitation of the keto tautomer (210) and yields the o-quinone methide (211)171 this is readily trapped as the ether... 

Acenaphthylene, indene, and styrene undergo periselective 4 + 2-cycloaddition with 3-ethoxycarbonyl-2//-cyclohepta[Z>]furan-2-one in high yield.152... 

The 8 + 2-cycloaddition of 2//-cy c I o h cpta[h ] furan -2 - one (155) with acyclic 1,3-dienes provides a facile route to bicyclo[5.3.0] ring systems (156) (Scheme 61).291 2H-Benzo[Z>]thiete in the o-quinoid form undergoes 8 + 2-cycloaddition with 1,3-dithiolane-2-thione, l,3-dithiole-2-thiones, and adamantanethione to produce 4//-1,3-benzoditliianes.292... 

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