2-Amino-3-mercapto-5-methoxypyrazine

Methoxy-2-methylthiazolo[4,5-h]pyrazine (2), when refluxed with aqueous methanolic sodium hydroxide, has been shown to give 2-amino-3-mercapto-5-methoxypyrazine (805, 1011). 

Methoxy-2-methylthiazolo[4,5-Z>]pyrazine (3) refluxed with IN sodium hydroxide in methanol gave 2-amino-3-mercapto-5-methoxypyrazine (4) (805, 1011), and 3,2 5,6-bis[(l, 3-diethyl-2,4-dioxo-l, 2,3,4-tetrahydro)- , 4-pyrimidino]-pyrazine refluxed in ethanol with N sodium hydroxide for 2.5 hours gave 2,6-bis(ethylamino)-3,5-bis-A -ethylcarbamoylpyrazine (1169). 

Significant aliphatic sulfur compounds are methional, 3-methyl-but-2-ene-1-thiol, 3-mercapto-3-methylbutan-l-ol (8-124), its ester 3-mercapto-3-methylbutyl formate, methanethiol and dimethyltrisulfide. 3-Mercapto-3-methyl-l-ol also occurs in passion fruit and blackcurrant, and as a putative cat pheromone in cat urine, where it is formed as a degradation product of amino acid L-felinine (see Section 2.2.1.2.2). Of more than 70 known pyrazines, the most important compounds in roasted coffee are isopropylpyrazine, 2-isobutyl-3-methoxypyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 2,6-dimethyl-3-vinylpyrazine and 2-ethyl-6-methyl-3-vinylpyrazine. Pyridine and its alkyl derivatives and bicyclic pyridines have a negative impact on the quality of coffee aroma. Important aromatic... 

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