Synthesis of 1-alkyl-2-nitroimidazole-5-carboxaldehydes

We report the preparation of 1-methyl- and 1-ethyl-2-nitroimidazole-5-carboxaldehydes (Ia,b). For Ia three different routes of synthesis are described, which appear of general value for preparing 1-alkyl substituted 2-nitroimidazole-5-carboxaldehydes.