Pyrazine, 2-isobutyl-3-methoxy

Several sensory modalities can be involved in complex interactions involving at least three cues rats learnt better to associate the bitter taste of quinine in water with a context such as a black or white box if a pyrazine was also present (the specific compound used was 2-methoxy-3-isobutyl pyrazine) (Kaye etal, 1989). It is said the odor potentiates learning the connection between taste cue and context. ... 

Galbanum Ferula galbaniflua Boiss., F. rubricaulis Boiss. 2-Methoxy-3-isobutyl pyrazine, 5-sec-butyl-3-methyl-2-butenethioate, 1,3,5-undecatriene as minor components, and monoterpene hydrocarbons (75), sesquiterpene hydrocarbons (10), lactones umbeUic acid, umbeUiferone... 

Chilli or paprika is used for flavour, not heat, in some cuisines. Flavour is a complex sensation determined in the mouth. One of the most potent volatiles known to humans is found in chilli, the pyrazine 2-methoxy-3-isobutyl-pyrazine, the green bell pepper smell. Reports indicate that humans can detect this odour at two parts per trillion. Luning et al. (1994) reported the presence of more than 80 odour compounds in C. annuum. C.frutescenscv. Tabasco contained 125 compounds whose relative abundance changed with the season of harvest. The composition of aroma compounds of Tabasco differed significantly from that of the green... 

There are many reports of Pseudomonas cultures producing musty, earthy, and potato-like odors ( l-6). The work of Morgan et al. (T) established 2-methoxy-3-isopropyl pyrazine to be partially responsible for these odors. Subsequently, 2-methyoxy-3-isopropyl pyrazine was found in bell peppers (8), a similar compound 2-methoxy-3-secbutyl pyrazine was identified in galbanum oil (9), and several 2-methoxy-3-alkyl pyrazines were identified in various raw botanicals (10). The odor threshold exhibited by 2-methoxy-3-isobutyl pyrazine (1 part in 10 indicates flavor significance for these compounds even at the exceptionally low concentrations in which they occur in foods and other natural products Producing these compounds from microbial fermentations could be an economical source of flavor for the food industry. 

Closely related compounds, even enantiomers, may not show similar binding affinities. OBP1 specifically bound 2- H-3 -isobutyl-3-methoxypyrazine, whereas OBP2 did not a derivative compound (2-isobutyl-3-methoxy-pyrazine) was unable to displace ligands from OBP-2 (Lobel et al., 1998). 

Methoxypyrazines 3-isobutyl-2-methoxy-pyrazine, 3-isopropyl-2-methoxypyrazine Strong X No ... 

Pyrazine, 3-isobutyl-2-methoxy-occurrence, 3, 192-193 Pyrazine, 3-isopropyl-2-methoxy-occurrence, 3, 193... 

Isobutyl-3-methoxy pyrazine (3-Isobutyl-2-methoxy pyrazine) i-c4H9 och3... 

Isobutyl-2-methoxy-3-methyl -pyrazine OCHj CH3 i-C4H9 ... 

Geosmin, 2-isopropyl, 3-methyox pyrazine, 2-isobutyl-3-methoxy-pyrazine, 2-methyl isobomeol, 2,3, 6 trichloroanisole ... 

Methyl 6-benzyloxy-5-isobutyl-3-methoxy-2-pyrazinecarboxylate 4-oxide (121, R = C02Me) gave 2-benzyloxy-6-hydroxymethyl-3-isobutyl-5-methoxy-pyrazine 4-oxide (121, R = CH2OH) [LiAl(OBu03H, THF, 0 7°C, 18 h ... 

Isobutyl-3-methoxy-5-[3-(tetrahydropyran-2-yloxy)propyl]pyrazine (132) gave 2-(3-hydroxypropyl)-5-isobutyl-6-methoxypyrazine (133) (TsOH, MeOH, 20°C, ultrasonication, 2 h > 95%) 295 analogues likewise.298... 

Hydroxypropyl)-5-isobutyl-6-methoxypyrazine (157, R = Hu ) gave 2-isobutyl-3-methoxy-5-(3-phthalimidopropyl)pyrazine (158, R = Hu ) (phthal-imide, Et02CN=NC02Et, Ph3P, A, 20°C, 12 h 93%), and thence 2-(3-amino-propyl)-5-isobutyl-6-methoxypyrazine (159, R = Hu ) (H2NNH2.H20, EtOH, reflux, 4 h 83%) 295 2-(3-aminopropyl)-5-isopropyl-6-methoxypyrazine (159, R = Pfl)298 and other homologues295,298 were made similarly. 

Dibenzyloxy-3-isobutyl-6-(tetrahydropyran-2-yloxymethyl)pyrazine 4-oxide (171) gave 2-benzyloxy-3-isobutyl-5-methoxy-6-(tetrahydropyran-2-yloxym-ethyl)pyrazine 4-oxide (172) (NaH, Bu4NBr, MeOH, Mc2NCHO, 20°C, N2, 40 min 91% the selective transalkoxylation of the 5-benzyloxy group may be due to activation by the adjacent /V-oxidc entity).848... 

Isobutyl-6-isopropyl-2(17/)-pyrazinone 6-Isobutyl-3-isopropyl-2(17/)-pyrazinone 2-Isobutyl-3-methoxy-5,6-dimethylpyrazine 2-Isobutyl-3-methoxy-5-(2-methy]prop-1 -enyl)pyrazine... 

Although most of the alkylpyrazines are formed through thermal Interactions of components in food, methoxy-substltuted pyrazlnes are mainly derived from biosynthetic pathways. 2-Isobutyl-3-methoxy-pyrazine Isolated from bell pepper by Buttery at al. (14) is one of the most significant flavor compounds discovered. This characteristic bell pepper aroma compound has an extremely low odor threshold of 0.002 ppb in water (15). 

Demethylation of 5-(2 -hydroxy-2 -methylpropyl)-2-isobutyl-3-methoxypyrazine occurred on refluxing with 10% hydrochloric acid to give 3-hydroxy-5-(2 -hydroxy-2 -methylpropyl)-2-isobutylpyrazine but 2-isobutyl-3-methoxy-5-(2 -methylprop-l -enyl)pyrazine and 3-hydroxy-24sobutyl-5-(2 -methylprop-l -enyl)pyrazine were also produced (113b). 

Methoxypyrazines (31) have been prepared by diazomethane methylation of 2-hydroxy-3-isobutylpyrazine (60, 311, 367), 2-hydroxy-3-isopropylpyrazine (59, 367), 2-hydroxy-3-propyl(ethyl or hexyl)pyrazine (367), 3-hydroxy-2-isobutyl-5(and 6)methylpyrazine and 2-hydroxy-3-isobutyl-5,6-dimethylpyrazine (368), 2,3-dihydroxypyrazine (832), 2-hydroxy-5-methoxy- and 2,5-dihydroxy-3,6-diphenyl-pyrazine (832), 2-hydroxy-6-methoxy(and benzyloxy)pyrazine (832), 2,6-dihydroxy-3,5-diphenylpyrazine (873), 2,3,5-trifluoro-6-hydroxypyrazine (851), 2-chloro-6-hydroxy-3,5-diphenylpyrazine (873), 2-chloro-6-hydroxy-5-methyl-3-phenylpyrazine (873), 2-chloro-6-hydroxy-3-methyl-5-phenylpyrazine (873), 5,6-dichloro-1 -cyclohexyl-34iydroxy-2-oxo-l, 2-dihydropyrazine (853), 2-chloro-5-hydroxy-3-methoxy-6-methoxycarbonylpyrazine (881), 2-(4 -amino-3, 5 -dibromo-phenylsulfonamido)-3Tiydroxy-6-methoxypyrazine (881), 2-amino-3-hydroxy-... 

Boron tribromide in dry chloroform was used to convert 3-isobutyl-6-isopropyl-1-methoxy-2-oxo-l, 2-dihydropyrazine to 2-hydroxy-3-isobutyl-6-isopropylpyrazine 1-oxide, and 6-isobutyl-3-isopropyl-l-methoxy-2-oxo-l, 2-dihydropyrazine behaved similarly (740a). Ohta (843) reports the preparation of 2-hydroxy-3,6-diisobutyl-pyrazine 1-oxide from 3,6-diisobutyl-l-methoxy-2-oxo-l, 2-dihydropyrazine (as intermediate) and hydrogen iodide. 

Investigation of Mutant Strains. Murray (14) suggested that the amino acids valine, leucine and isoleucine were precursors of 2-methoxy-3-isopropyl, 3-isobutyl and 3-secbutyl pyrazines, respectively. The effects of mutations in the branched chain amino acid pathways on the synthesis of these compounds was investigated. 

Aminopropyl)-5-isobutyl-6-methoxypyrazine (164) gave 2-isobutyl-3-methoxy-5-[3-(3-nitroguanidino)propyl]pyrazine (165) [MeSC(=NH)NHNO2, EtOH, 40°C, 5 min, then 20°C, 24 h 85%]. 

Pyrazine, 2-methoxy-3-(2-methylpropyl)-, 2-isobutyl-3-methoxypyrazine, 2-methoxy-3-(2-methylpropyl) pyrazine, 3-isobutyl-2-methoxypyrazine [24683-00-9] FEMA 3132... 

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