2- Isobutyl-3-methyl-5,6-dihydropyrazine

Aspergillic acid (H 65, 195), 6-,vet-butyl-l-hydroxy-3-isobutyl-2( l//)-pyrazi-none, a mycotoxic Aspergillus sp metabolite [490-02-8],1024 Astechrome, 3-(l-hydroxy-3-methoxy-5-methyl-6-oxo-l,6-dihydropyrazin-2-yl-methyl)-7-(3-methylbut-2-enyl)indole Fe complex, an Aspergillus sp metabolite [75310-10-0]90... 

OPC-15161, 3-[(5-isobutyl-3-methoxy-4-oxido-6-oxo-l,6-dihydropyrazine-2-yl)methyl]indole (X-ray confirmation), a Thielavia sp fungus metabolite inhibitor of superoxide anion generation [121071-92-9],1166... 

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-... 

A large number of 2-alkyl-3-methoxypyrazines has been isolated from raw vegetables (59, 60, 64, 65, 69, 80, 1099), bell peppers (60,61) and gambanum oil (49). 2-Isobutyl-3-methoxypyrazine is already finding commercial use as a flavoring material (368) and 2-ethoxy-3-methylpyrazine may be used for pineapple flavor (981). The odor characteristics (367, 368, 976, 977) and structure (977) of some alkoxy alkylpyrazines have been examined. 3-Guanidino-6-hydroxymethyl-l-methyl-2-oxo-l,2-dihydropyrazine has been isolated from seeds of Stizolobium hassjoo and on mild alkaline hydrolysis gave 3-hydroxy-6-hydroxymethyl-l -methyl-2-oxo-l, 2-dihydropyrazine (1060). 

Hydroxypyrazine 1 oxide was reduced with hydrogen at atmospheric pressure over Raney nickel to 2-hydroxypyrazine (108) [but failed to react with phosphorus trichloride in chloroform (108)], and 3-hydroxy-2-isobutyl-5-isopropylpyrazine 1,4-dioxide was reduced with hydrogen over nickel to 3-hydroxy-2-isobutyl-5-isopropylpyrazine (740a). 2-(A -Anilino-yV-methylcarbamoyl)-4-methyl-3oxo-3,4-dihydropyrazine 1 oxide with sodium dithionite produced 3-(A -anilino-A -methyl-carbamoyl)- -methyl-2oxo-l, 2-dihydropyrazine (1137). 

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