3- l- furanone

Dodecyloxy-3-(2-chloroethyl)-2-methyl-4//-pyrido[l,2-n]pyrimidin-4-one 317 was obtained by cyclization of 3- l-[(3-dodecyloxy-2-pyridyl)ami-no]ethylidene -4,5-dihydro-2(3//)-furanone (316) in boiling POCI3 (95MIP4). 

Similarly, (A )-( )-3-(2-methoxymethyl-l-pyrrolidinyl)-l-phenylpropene118 121, after lithia-tion and addition of acetone, acidic hydrolysis and oxidation of the intermediate lactol, gives (5)-dihydro-5,5-dimethyl-4-phenyl-2(3/f)-furanone with 98% ee and 54% overall yield. Thus, these sequences constitute asymmetric homoaldol addition. 

CN (35-cij)-3-ethyldihydro-4-[(l-meihyl-l//-imidazol-5-yl)methyl]-2(3/f)-furanone monohydrochloride... 

A key step in the approach to 3(2//)-furanone ring systems via the acid-catalyzed cyclization-dehydration of appropriately substituted a -hydroxy-l,3-diketones involves the acylation of a-hydroxy-ketone dianions 11141... 

Thermolysis of D-fructose in acid solution provides 11 and 2-(2-hydrox-yacetyl)furan (44) as major products. Earlier work had established the presence of 44 in the product mixtures obtained after acid-catalyzed dehydrations of D-glucose and sucrose. Eleven other products were identified in the D-fructose reaction-mixture, including formic acid, acetic acid, 2-furaldehyde, levulinic acid, 2-acetyl-3-hydroxyfuran (isomaltol), and 4-hydroxy-2-(hydroxymethyl)-5-methyl-3(2//)-furanone (59). Acetic acid and formic acid can be formed by an acid-catalyzed decomposition of 2-acetyl-3-hydroxyfuran, whereas levulinic acid is a degradation prod-uct of 11. 2,3-Dihydro-3,5-dihydroxy-6-methyl-4//-pyran-4-one has also been isolated after acid treatment of D-fructose.The pyranone is a dehydration product of the pyranose form of l-deoxy-D-eo f o-2,3-hexodiulose. In aqueous acid seems to be the major reaction product of the pyranone. 

Bulaquine is a mixture of 3 -l-4-6(-methoxy-8-quinolinyl) aminopentyl ethylidenedihydro-2-(3H) furanone and it s tautomers. 

Onion Allium cepa L. Methylpropyl disulphide, dipropyl disulphide, propenylpropyl disulphide, 2-hexyl-5-methyl-3(2H)-furanone... 

Twenty-nine odour-active compounds were detected by using aroma extract dilution analysis (AEDA) [60]. The results of AEDA together with GC-MS analysis showed ethyl 2-methylbutanoate (described as fruity flavour), followed by methyl 2-methylbutanoate and 3-methylbutanoate (fruity, apple-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet, pineapple-like, caramel-like), d-decalactone (sweet, coconut-like), l-( ,Z)-3,5-undecatriene (fresh, pineapple-like), and a unknown compound (fruity, pineapple-like) as the most odour-active compounds. 

Reaction of the 2-acetoxy-3(2//)-furanones (526) with monosubstituted hydrazines gives good yields of the pyridazinium-5-olates (527) together with varying amounts of isomeric products. Alkyl derivatives (527 R = alkyl) have also been prepared by base-catalyzed alkylation (Mel, Me2SO4, PhCH2Cl) of 3-methyl-6-phenyl-5-ethoxycarbonyl-4( 1 //)-pyridazinone. Reduction of the diphenyl compound 527 (R = Ar = Ph) by zinc and hydrochloric acid gives 3-ethoxycarbonyl-5-hydroxy-5-methyl-l,2-diphenyl-2-pyrrolin-4-one (528 R = Ar = Ph) (Scheme 21... 

CYCLOADDITION Alumina chloride. l,2-Bis(trimethylsilyloxy)cyclo-butene. 2,2-Dimcthyl-3(2//)-furanone. Lthylaluminum dichloridc. Kctcnc diethyl acetal.. Methyl cyclobutene-carboxylate. Trimethyl-1,3-dioxolen-one. Zinc chloride. 

Hydration of 2-butyne-l,4-diols (1). Treatment of 1 with acetic anhydride and pyridine (25°) results in acetylation of the less hindered hydroxyl group. When treated with AgC104, the monoacetate (2) is converted into the enol acetate of a dihydro-3(2H (-furanone (3, equation I). The regioisomeric dihydro-3(2H)-furanone is formed by hydration of 1 with Hg(OAc)2-Nafion-H preferentially (equation II).1... 

Maple Svrup. The typical flavor of maple syrup which originates during the heat concentration of maple sap in the presence of air has also been extensively investigated (70-80). Important sugar-based degradation products present in maple syrup include 3-methylcyclopentane-l,2-dione and 2,5-dimethyl-4-hydroxy-3(2H)-furanone. 

Furans are the most abundant products of the Maillard reaction and they account for the caramel-like odor of heated carbohydrates (8). Some sugar degradation compounds, such as maltol, isomaltol, 4-hydroxy-5-methyl-3(2H)-furanone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 2-hydroxy-3-methyl-2-cyclopentene-l-one (cyclotene), have odors usually described predominantly... 

Materials Employed. 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) of high purity was provided by International Flavors and Fragrances (IFF). L-cystine, injectable grade, was purchased from Ajinomoto Company, Tokyo, Japan. Reagent grade methylene chloride was purchased from Aldrich Chemical Company, and was freshly distilled prior to use. Spectral grade glycerol was obtained from a commercial source. 

Three compounds appear to be of particular importance in flavor volatiles identified by Ching (3) from beef diffusate or dried beef. These are 2-hydroxy-3-methyl-2-cyclo-penten-l-one, 4-hydroxy-5-methyl-3(2H)-furanone and 4-mercapto-5-methyl-tetrahydro-3-furanone. 

Hodge et al. (45) discussed mechanisms for formation of methyl furanones and related substances from Amadori compounds. They have been produced by heating D-ribose and D-ribose phosphate with ammonia (46 47). Hicks and Feather (48) demonstrated that the Amadori compound 1-benzylamino-l-deoxy-D-threo-pentulose dehydrates to 4-hy-droxy-5-methyl-3(2H)-furanone and it has also been identified as a degradation product of L-ascorbic acid. This compound is believed to be formed from ribose-5-phosphate, and gained prominence when it was isolated from beef by Tonsbeck et al. (49). It became more apparent as a precursor of meat flavor when Van den Ouweland and Peer (50) reacted it and its thio analog with HaS to produce a number of sulfur compounds, some of which had meaty odors. 

Single-photon emission computed tomography Tricarbonyltris(2-methoxyisobutyl isonitrile)99mTc complex Hexakis(2-ethoxy-isobutylisonitrile)99mTc complex trans[(l,2-Bis(dihydro-2,2,5,5-tetramethyl-3(2H)furanone-4-methylene-imino)ethane) bis(tris(3-methoxy-l-propyl)phosphine)]99mTc complex Hexakis(2-methoxyisobutyl isonitrile)"mTc complex [l,2-Bis bis(2-ethoxyethyl)phosphino ethane]20299mTc complex... 

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