2- Amino-3-cyano-5-methoxymethylpyrazine 1-oxide

Certain a-chloromethylpyrazine A -oxides have been deoxygenated with phosphorus trichloride. Treatment of 2-amino-5-chloromethyl-3-cyanopyrazine 1-oxide (and 2-amino-3-cyano-5-methoxymethylpyrazine 1-oxide) with phosphorus trichloride at room temperature in tetrahydrofuran resulted in smooth deoxygenation to 2-amino-5-chloromethyl-3-cyanopyrazine (and 2-amino-3-cyano-5-methoxy-methylpyrazine) (529), whereas 2-amino-6-chloromethyl-3-cyanopyrazine 1-oxide was best deoxygenated to 3-amino-5-chloromethyl-2-cyanopyrazine by phosphorus trichloride in refluxing tetrahydrofuran (534). The more vigorous conditions necessary for the last reaction may be a reflection of increased steric hindrance at the fV-oxide grouping (529). Use of solvents like chloroform or dioxane led to slow reactions which were accompanied by the formation of numerous unidentified by-products (534). 

The preparation of extranuclear alkoxypyrazines from extranuclear halogeneo-pyrazines has been described in Section V.6A (654, 672,679,685, 687,688,694, 756, 872, 1027). 2-Amino-3-cyano-5-methoxymethylpyrazine 1-oxide with phosphorus trichloride in tetrahydrofuran afforded 2-amino-3-cyano-5-methoxy-methylpyrazine (529) and 3-(bromoacetamido)-l-ethoxy4-oxopentane (44) with alcoholic ammonia gave 5-hydroxy-3-(2 -ethoxyethyl)-2-methylpyrazine (45) (248). 

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