5-Bromo-2,3-diphenylpyrazine

Bromo-5,6-dimethyl-2(177)-pyrazinone 5-Bromo-3,6-dimethyl-2(l 77)-pyrazinone 5-Bromo-2-dimethylsulfimidopyrazine 2-Bromo-5,6-diphenyl-3-propylpyrazine 2-Bromo-3,5-diphenylpyrazine... 

Bromination of 5-s-butyl-3-hydroxy-2-isobutylpyrazine (deoxyaspergillic acid) in aqueous solution or acetic acid gave 2-bromo-3-s-butyl-5-hydroxy-6-isobutylpyrazine (bromodeoxyaspergjllic acid) (87) bromination of 2-s-buty-3-hydroxy-5-isobutyl-pyrazine in acetic acid gave 2-bromo-6-s-butyl-5-hydroxy-3-isobutylpyrazine (93) and 3-hydroxy-2,5-diphenylpyrazine behaved similarly (282). This procedure with bromine in acetic acid was unsatisfactory when applied to simpler hydroxypyrazines (817), and bromination of 3,6(and 5,6)-disubstituted-2-hydroxypyrazines and 2-... 

Refluxing phosphoms tribromide converted 2-bromo-3-hydroxy-5,6-diphenyl-pyrazine and 2-bromo-5-hydroxy-3,6-diphenylpyrazine to the dibromopyrazines 2,3-dichloro-5,6-dimethylpyrazine and 2,5-dichloro-3-phenylpyrazine to the dibromopyrazines (817) 5-chloro-2,3-diphenylpyrazine (and its 6-ethyl derivative) to 5-bromo-2,3-diphenylpyrazine (and its 6-ethyl derivative) (866) and 2-hydroxy-... 

Hydroxy-3-nitro-5,6-diphenylpyrazine with acetyl bromide, iodine bromide, or dry hydrogen bromide in dry dioxane gave 2-bromo-3-hydroxy-5,6-diphenyl-... 

Bromo-3-hydroxy-5,6-dimethylpyrazine and 2-bromo-5-hydroxy-3,6-diphenyl-pyrazine with phosphoryl chloride afforded 2,3-dichloro-5,6-dimethylpyrazine and 2,5-dichloro-3,6-diphenylpyrazine, respectively (817) and the bromo substituent in 2-amino-3-bromo-5,6-dimethylpyrazine and its p-aminobenzenesulfonyl derivative have been replaced by chlorine on treatment with aqueous hydrochloric acid in ethanol (812). 

Bromopyrazine and anhydrous ammonia in ethanol gave 2-aminopyrazine (939), and 5-bromo-23-diphenylpyrazine with ethanolamine at 125° gave 5-(2 -hydroxyethyl)amino-2,3-diphenylpyrazine (834). 

Section II.7 describes some ring closures of the C-C-N-C-C, N-C-C-N-C-C, and N-C-C-N-C-C-N systems to give hydroxypyrazines (248, 365a, 477, 479, 480-483) more information can be found in reference 1054. Newbold and Spring (89) described the reaction of 2-bromo-A -(r-methyl-2 -oxopropyl)propionamide with ethanolic ammonia to give 2-hydroxy-3,5,6-trimethylpyrazine and Masaki et al. (551) have described the reaction of A -leucyl-6>-benzyIhydroxylamine (2) with phenacyl bromide in methanol saturated with ammonia to give 3-hydroxy-2-isobutyl-5-phenylpyrazine and 2,5-diphenylpyrazine. 

---