Action of nitrous acid on some methylpyrimidines

Abstract

The action of aqueous sodium nitrite in acid solution on simple 2-mercapto-methylpyrimidines gives bipyrimidinyl disulphides. Similar reactions with 2-hydroxy-4-methylpyrimidines result in attack at the methyl groups giving (hydroxyiminomethyl)pyrimidines, whereas 2-amino-4-methylpyrimidines undergo concomitant deamination and methyl attack. Application of this nitrosation procedure to 1,4,5,6-tetramethylpyrimidin-2-one affords 1,4,5-trimethylpyrimidine-2,6-dione; an analogous reaction occurs with the corresponding 2-thione. This represents a novel pyrimidine demethylation reaction.

The bipyrimidinyl disulphides show potential as reagents for the spectroscopic determination of thiol groups and nitrite ion.