Pyrazine 1-oxide, 2,5-dialkyl

Pyrazine, 1,4-dialkyl-1,4-dihydro-isomerization, 3, 178 Pyrazine, dichloro-synthesis, 3, 187 Pyrazine, 2,3-dichloro-oxidation, 3, 169... 

Comparative A -oxide activation was likewise observed when other amines such as hexylamine, aniline, benzylamine, piperidine, and dimethylamine were used. It was also noted, in every example studied, that amination of the chloropyrazine A -oxide or alkylchloropyrazine 7V-oxide at elevated temperatures in a sealed vessel gave mixtures containing greater or lesser amounts of deoxygenated halogeno-pyrazine or aminopyrazine (921). Similar enhanced activation by theTV-oxide group was observed when 3-chloro-2,5-dimethylpyrazine and its 1-oxide in reaction with various amines were compared, although dialkyl substitution further retarded overall aminolysis (793,921). 

V,Af-Dialkyl-3-phenylpyrido[3,4-h]pyrazin-2-amine 4-oxides 1 are reduced by sodium di-thionite to give the corresponding pyrido[3,4-/r]pyrazines 2.125... 

The oxidation of some ketones with ammoniacal ferricyanide provides a valuable route to a-amino-aa-dialkyl ketones (Scheme 112), isolated as their hydrochlorides to preclude dehydrative dimerization to dihydro-pyrazines. 

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