Hydroxy-4-methyl-2 5H -furanone

Recently, 118 was applied to the synthesis of (9Z,9 Z)-lycopene [(9Z,9 Z)-31] [42]. The (2Z)-ester 118 was transformed into (2Z)-4,5-didehydrofarnesal (119) by reduction of 118 with DIBAH and oxidation of the intermediate allylic alcohol with Mn02. An inverse Wittig condensation of 119 with the Cio-diphosphonium salt 10 gave an isomeric mixture from which pure (9Z,9 Z)-lycopene [(9Z,9 Z)-31] was isolated after isomerization and crystallization from hexane (see Chapter 3 Part V). 

Thus the synthesis of aliphatic C40- and Cso-carotenoids containing the end groups shown below is selectively treated in the corresponding Sections B - L of this Chapter, in addition to the synthesis of diapocarotenoid (all- )-methylbixin (534). The synthesis of the acyclic end group of aleuriaxanthin (81), which occurs only in this monocyclic carotenoid, is described in Worked Example 5. 

For additional information the reader is referred to the original publications, the references to which can be found in the Key to Carotenoids and the Appendix II of this Volume. The Worked Examples describe in detail the experimental procedures for important reactions. 

Some 50 carotenoids with an unsubstituted / end group have been found in Nature, the most important one being lycopene (31). 

The two strategies Cio + C2o + Cio = C4o and Ci5 + Cio + Ci5 = C4o have also been applied to synthesize fourteen different (E/Z)- somdxs of lycopene (31) by use of stereochemically pure phosphonium salts [5] (see Chapter 3 Part V). 

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The influence of the sensitivity of the assessors on AEDA has been studied [11], with the result that the differences in the FD factors determined by a group of six panellists amount to not more than two dilution steps (e.g. 64 and 256), implying that the key odorants in a given extract will undoubtedly be detected. However, to avoid falsification of the result by anosmia, AEDA of a sample should be independently performed by at least two assessors. As detailed in [6], odour threshold values of odorants can be determined by AEDA using a sensory internal standard, e.g. ( )-2-decenal. However, as shown in Table 16.6 these odour threshold values may vary by several orders of magnitude [8] owing to different properties of the stationary phases. Consequently, such effects will also influence the results of dilution experiments. Indeed, different FD factors were determined for 2-methyl-3-furanthiol on the stationary phases SE-54 and FFAP 2 and 2 , respectively. In contrast, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone showed higher FD factors on FFAP than on SE-54 2 and 2, respectively. Consequently, FD factors should be determined on suitable GC capillaries [8]. However, the best method to overcome the limitations of GC-O and the dilution experiment is a sensory study of aroma models (Sect. 16.6.3). 

Ethyl-3-hydroxy-4-methyl-2(5H)-furanone [2H3]ethyl Blank et al., 1993... 

Blank, I., Schieberle, P., and Grosch, W. 1993. Quantification of the flavour compounds 3-hy-droxy-4,5-dimethyl-2(5H)-furanone and 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone by stable isotope dilution assay. In Progress in Flavour and Precursor Studies (P. Schreier and P. Winterhalter, eds.). Allured Publishing, Wheaton, 111. 

Ethyl 3-Hydroxy 4-Methyl 2(5H)-Furanone View Flavor Chemical... 

Dimethoxy Phenol 3,4-Dimethyl 1,2-Cyclopen tandione 5-Ethyl 3-Hydroxy 4-Methyl 2(5H)-Furanone 3-Ethyl Pyridine Furfuryl Mercaptan Geranyl Isovalerate 2,3 -Heptandione (Z)-3-Hexenyl Butyrate (Z)-3-Hexenyl Formate Hexyl Butyrate Hexyl Hexanoate Isoamyl Isobutyrate Isobutyl Formate Isobutyl Hexanoate Linalool Oxide... 

The lactol 5-hydroxy-4-methyl-2(5H)-furanone (114) can be regarded as the cyclic form of (Zj-3 methyl-4-oxobut-2-enoic acid (115) (Scheme 12) [11]. A 2 1 mixture of (2Z,4 , 6 )-3,7,1 l-trimethyldodeca-2,4,6,10-tetraenoic acid (116) and its corresponding (2Z,4Z,6E)-isomer was obtained by Wittig condensation between geranyltriphenylphosphonium bromide (117) and the lactol 7/4 [41]. The mixture of acids was esterified with ethereal diazomethane, and the resulting methyl esters were separated on silica gel to obtain isomerically pure 118. 

Two molecules of carbon monoxide were successively incorporated into an epoxide in the presence of a cobalt catalyst and a phase transfer agent [29]. When styrene oxide was treated with carbon monoxide (0.1 MPa), excess methyl iodide, NaOH (0.50 M), and catalytic amounts of Co2(CO)8 and hexadecyltrimethylammonium bromide in benzene, 3-hydroxy-4-phenyl-2(5H)-furanone was produced in 65% yield (Scheme 7). A possible reaction mechanism was proposed as shown in Scheme 8 Addition of an in situ... 

Obt. from the Japanese gorgonian Euplexaura flava. 3 4 -Dihydro 3-(6,9J2-Docosatrienyl)-5-hydroxy-5-methyl-2 5H)-furanone. From E. flava. 

Blank, I., Lin, J., Fumeaux, R., Welti, D.H., and Fay, L.B. 1996. Formation of 3-hydroxy-4,5-di-methyl-2(5H)-furanone (sotolone) from 4-hy-droxy-L-isoleucine and 3-amino-4,5-dimethyl-3,4-dihydro-2(5)-furanone. J. Agric. Food Chem. 44 1851-1856. 

Deoxo, 7 -hydroxy [148077-12-7]. 4- 7-Hydroxy-1-noneny[)-3-methyl-2 5H)-furanon . Appenolide C C14H22O3 M 238.326... 

Updated Entry replacing V-70003 5-[12-(3-Furanyl)-2fiJ0-trimethyl-6,10-tridecadienylidene -4-hydroxy-2-methyl 2(5H)-furanone, 9CI [51847-87-1]... 

FIGURE 7.10 Structures of volatile compounds characterized from toasty caramel aroma released in wine from toasted woods during aging. (1) 3,5-dihydroxy-2-methyl-4H-pyran-4-one (2) 3-hydroxy-2-methyl-4H-pyran-4-one (3) 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) (4) 4-hydroxy-2,5-dimethylfuran-3(2H)-one (furaneol) (5) 2,3-dihydro-5-hydroxy-6-methyl-4H-pyran-4-one (dihydromaltol) (6) 2-hydroxy-3-methyl-2-cyclopenten-l-one (or cyclotene) (Cutzach et al., 1997 ) (7) 3-hydroxy-4,5-dymethyl-2(5H)-furanone (Sotolon Camara et al., 2006a,b,c) (8) 2-furanmethanethiol (furfurylthiol Tominaga et al., 2000). 

Figure 5.2.10. Cellulose pyrolysate obtained at 59CP C by Py-GC/MS. The separation was done on a Carbowax type column. 1 CO2, 2 acetaldehyde, 3 acetone, 4 2-butanone, 5 2,3-butandione, 6 toluene, 7 water, 8 cyclopentanone, 9 methylfuran, 10 3-hydroxy-2-butanone, 11 hydroxypropanone, 12 cyclopent-1-en-2-one, 13 2-methylcyclopentenone, 14 acetic acid, 15 acetic acid anhydride, 16 furancarboxaldehyde, 17 methylcyclopentenone, 18 dimethylcyclopentenone, 19 5-methylfurancarboxaldehyde, 20 2,3-dihydro-2-furanone, 21 furan-2-methanol, 22 3-methylfuran-2-one, 23 2(5H)-furanone, 24 hydroxycyclopentenone, 25 3,5-dimethylcyclopentan-1,2-dione, 26 2-hydroxy-3-methyl-2-cyclopenten-1-one, 27 2-hydroxy-3-ethyl-2-cyclopenten-1-one, 28 2,3-dimethyl-2-cyclopenten-1-one, 29 phenol, 30 dimethylphenol, 31 3 thyl-2,4(3H,5H)-furandione, 32 3-butenoic acid, 33 1,4 3,6-dianhydro-a-D-glucopyranose, 34 5-(hydroxymethyl)-furfural.

Figure 5.2.11. Cellulose pyrolysate obtained at 59(P C and separated on a methyl silicone with 5% phenyl silicone type column. 1 acetic anhydride, 2 pentanal, 3 2-hydroxybutanedialdehyde, 4 1,4-dioxadiene, 5 tetrahydro-2-furanmethanol, 6 2-(hydroxymethyl)-furan, 7 3-methyl-2-hexanone, 8 2-methoxy-2,3-dihydrofuran, 9 2(5H)-furanone, 10 1-acetyloxypropan-2-one, 11 hydroxycyclopentenone, 12 5-methylfurfural, 13 2,3-dihydro-5-methylfuran-2-one, 14 1-cyclopentylethanone, 15 2-hydroxy-3-methyl-2-cyclopenten-1-one, 16 3,5-dimethylcyclopentan-1,2-dione, 17 unknown, 18 3-ethyl-2,4(3H,5H)-furandione, 19 6-methyl-1,4-dioxaspiro[2,4]heptan-5-one, 20 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one, 21 1,4 3,6-dianhydro-a-D-glucopyranose, 22 5-(hydroxymethyl)-furfural, 23 4-cyclopenten-1,2,3-triol, 24 5-ethyl-3-hydroxy-4-methyl-tetrahydrofuran-2-one, 25 levoglucosan, 26 1,6-anhydro-p-D-glucofuranose.

DIMETHYL-3-HYDROXY -2(5H)-FURANON 3-HYDROXY-4-METHYL-5-ETHYL 2(5H)-FURANON FURFURYL-MERCAPTANE 2-METHYL FURAN-3-THI0L... 

Hydroxy-4,5-dimethyl-2(5H)-fiiranone (Sotolon), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol) and 2-hydroxy-3-methyl-2-cyclopenten-l-one (Cyclotene) were from Aldrich (Steinheim, Germany). 2-Acetyltetrahydropyridine and 2-acetyl-1-pyrroline were synthesized as previously described (8). 2-Hydroxy-3,4-dimethyl-2-cyclopenten-l-one was a gift from Dr. I. Blank (Nestle, Vers-chez-les-blanc, Switzerland). 

H)-Furanone, 5-ethyl-3-hydroxy-4-methyl- 172a, 174b, 1053, 3266, 3370 ... 

It has been suggested that the presence of aldehydes and methyl-ketones contribute to the rancio odor of barrel aged Port wine (2) and also in white wines (1). Other volatiles, were also studied in ports (5, 4, 5, 6, 7, 8). More recently, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon) has been suggested to be a key odorant in the aroma of aged port (9). This highly odor active molecule has been shown to contribute to the aroma of Jura wines vin jaunes 10, 13, 14, 15), vins doux naturels (14) Tokay wines 11), Botrytised wines (id) and Sherry wines (72). 

Hydroxy-2-methyl-4-pyrone 5-Ethyl-2(5H)-furanone a-TerpinoIene Octanal ... 

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