Pteridines. 47. Preparation and Chemistry of 2-Amino-6-carbalkoxy-3-cyano-5-substituted Pyrazine 1-Oxides: Synthesis of Pterin-6-carboxaldehyde

Article abstract of DOI:10.1021/jo01300a045

A new procedure for the synthesis of 2-amino-3-cyano-5-substituted pyrazines 9, useful intermediates for the synthesis of pteridines, is described.Oximation of β-keto esters 2 followed by reaction with aminomalononitrile provides 2-amino-6-carbalkoxy-3-cyano-5-substituted pyrazine 1-oxides 5.Protection of the amino group as its ((dimethylamino)methylene)amino derivative 9 followed by S_N2 decarbalkoxylation provides pyrazines 10 which on removal of the protecting group and deoxygenation give pyrazines 8.This method is designed to be of use in cases where the β-keto ester cannot be converted directly to the corresponding α-keto aldoxime 3.The procedure is applied to the synthesis of 2-amino-3-cyano-5-(dimethoxymethyl)pyrazine (8a), an intermediate in the synthesis of pterin-6-carboxaldehyde (1).