3- Amino-5-methyl-2- pyrazine

Pyrazine, tetrahydro-, 3, 177, 178 Pyrazine, 1,2,3,4-tetrahydro-synthesis, 3, 177 Pyrazine, 2,3,5-tri-t-butyl-synthesis, 3, 185 Pyrazine, 2,3,5-trichloro-nucleophilic substitution, 3, 176 Pyrazine, 2-vinyl-polymers, 1, 290-291 Pyrazine-3-carboxylic acid, 2-amino-methyl ester... 

Racemic /ru -2-(l-naphthylsulfonyl)-7- [4-amino-2-quinaxolinyl)amino-methyl]perhydropyrido[l,2-u]pyrazine was resolved into the optically active enantiomers by means of a Chiralpack column (01MIP20). 

Beim kurzen Erhitzcn in waBriger Natronlauge dehydratisiert 3-Amino-2-(amino-benzoyloxi-mino-methyl)-pyrazin in guter Ausbeute zu 3-(3-Amino-2-pyrazinyl)-2-phenyl-l,2,4-oxadi-azol (77% Schmp, 220-2230)211 ... 

Another key intermediate for pteridine synthesis was also seen in 2-amino-3-ethoxycarbonyl-5-phenylpyrazine 1-oxide which reacts with various amines to form the corresponding amides followed by cyclization with triethyl orthoformate giving 3-alkyl-6-phenyl-4(3/7)pteridinone 8-oxides <87JHC1109>. The synthesis of 2,4-diamino-6-methylpteridine 5-oxide (371) was achieved from 5-methyl-pyrazine-2-carboxamide (366) via the 4-oxide (367), a Hofmann degradation (368), bro-mination (369), and cyanation (370) followed by cyclization with guanidine to give (371) (Scheme 60) <93JHC841>. 

N- a-Chloro- a- [bis(trifluoromethyl)amino]methylene -N- a, a-dichloro-a-[bis-(trifluoromethyl)amino]methyl amine (293) gave 2,3,5,6-tetraks[bis(trifluo-romethyl)amino] pyrazine (294) (Ph3P, 120°C, 6 h 6% as a distillate/subli-mate a mechanism was suggested).1321... 

C yanoethyl)carbamoyl-3-formylamino-5-methylpyrazine boiled with N sodium hydroxide for 30 seconds gave 3-amino-2-cyanoethylcarbamoyl-5-methyl-pyrazine (435) 2,3-dichloro-5-formamido-6-formylpyrazine was readily deformyl-ated under acid or alkaline conditions (e.g., 2A( sodium carbonate at 20°) (430) and 2-formamido-3-(iniidazol-2-yl)pyrazine was deformylated by refluxing with 0.1 A hydrochloric acid for 4 hours and its 5,6-dimethyl derivative reacted similarly (455a). 

Musty/mouldy aroma defects in black pepper are caused by a mixture of 2,3-diethyl-5-methyl-pyrazine and 3-isopropyl-2-methoxy-pyrazine. Some samples of white pepper contain up to 2.5 mg/kg of skatole (odor threshold on starch 0.23 pg/kg), which together with 3- and 4-methylphenol can cause a fecal aroma defect. This aroma defect arises during fermentation (degradation of amino acids, e. g., tryptophan 3-methylindole), which is carried out to remove the flesh. On longer storage, this defect becomes more noticeable because intensive aroma substances, which disguise it in fresh white pepper, volatilize. 

Methyl pyrazinamine 2-Amino-3-methyl pyrazine C5H7N3 19838-08-5 109.130 nd (hx/ AcOEt) 174 ... 

Pyrazine, 2-amino-5-methyl-synthesis, 3, 180, 181 Pyrazine, 2-amino-5-phenyl-synthesis, 3, 180, 181... 

H-Pyrido[2,l-i]purine-9-carboxylic acid, 7-oxo-methyl ester, 5, 566 Pyrido[2,3-6]pyrazine, amino-nucleophilic attack, 3, 253 Pyrido[2,3-h]pyrazine, 6-chloro-reactions... 

Amino-3-Methoxy-5-Bromo-Pyrazine 7 grams of 2-amino-3,5-dibromo-pyrazine are boiled for 9 hours in a methanolic solution of sodium methylate (obtained from 0.65 gram of Na and 18.5 ml of methanol). By cooling a crystalline product is obtained, filtered and washed once with methanol and 2 to 3 times with water. The yield is 5.4 grams, melting at 138°C. 

---