2-Methyl-6,7-dihydro-577-cyclopentapyrazine

Manley et al. (1974) suggested that cyclopentapyrazines may result from the condensation of 2-hydroxy-3-methylcyclopent-2-en-l-one (D.68) with glyoxal or pyruvaldehyde and amino acids, and a mechanism of formation has also been suggested from a study on popcorn flavor by Walradt et al. (1970). Vitzthum and Werkhoff (1975) reported 17 new alkylated five-and six-membered bicyclic pyrazines in roasted coffee the mass spectra of these new constituents and particularly the fragmentation pathways of 2-methyl-(O.50) and of 6,7-dihydro-5-methyl-5//-cyclopentapyrazine (0.51) are discussed in detail. 

Cyclopentapyrazine, 6,7-dihydro-2-methyl-, 6,7-dihydro-2-methyl-5H-cyclopentapyrazine [23747-46-8]... 

Cyclopentapyrazine, 2-ethyl-6,7-dihydro-3-methyl-, 2-ethyl-6,7-dihydro-3-methyl-5H-cyclopentapyrazine [41330-35-2]... 

V ch3 5-methyl-6,7-dihydro[5//]cyclopentapyrazine [23747-48-0] nutty, roast odor... 

Dihydro-5/f-cyclopentapyrazine 2-Methyl-6,7-dihydro-5 -cyclo-pentapyrazine ... 

Others. For example, the odour of 2,5-dimethylpyrazine resembles roasted hazelnuts, and 2,6-dimethylpyrazine and trimethylpyrazine have a chocolate-like odour. Important components of coffee aroma include a number of pyrazines, such as 2,3-diethyl-3-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,6-dimethyl-3-vinylpyrazine and 2-ethyl-6-methyl-3-vinylpyrazine. The flavour-active components of popcorn and white bread are acetylpyrazine, 2-ethyl-3-methylpyrazine, 3-ethyl-2,5-dimethylpyrazine and 5-methyl-6,7-dihydro-5H-cyclopenta[fo] pyrazine. Cyclopentapyrazines, specihcaUy 6,7-dihydro-5H-cyclopenta[fo]pyrazines, are formed in reactions of cyclopen-tenolones with aminoketones and ammonia. 

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