A domino type one-flask synthesis of 1 -substituted-5 -aminoimidazole-4-carboxamides and ring transformation to pyrazine under microwave through suitable aminoimidazoliumcarboxamide

摘要

Reductive heterocyclisation of oximinocyanoacetamide 1 in the presence of ethyl orthoformate and appropriate amine affords l-substituted-5-aminoimidazole-4-carboxamides 2.4-Amino-5-carboxamido-3-diphenyImethy 1-1 -phenacylimidazolium bromide 4c,generated in situ from 2i,furnishes a ring expanded pyrazine derivative,3-( 1 -amino-1 -diphenylmethylamino)methyleno-2-oxo-6-phenylpyrazine 5 with methanolic alkali under microwave in excellent yield.