Dihalogentriphenylphosphorane in der Heterocyclensynthese, 29.1Eine einfache Synthese von Pteridin-4-onen aus 3-Amino-2-pyrazincarbonsäuremethylester und Pyrazino[3,1]oxazin-4-onen

Abstract

Dihalogentriphenylphosphoranes in the Synthesis of Heterocycles, 29.1 A Simple Synthesis of Pteridin-4-ones, from Methyl 3-Amino-2-pyrazinecarboxylate and Pyrazino[3,1]oxazin-4-ones Methyl 3-amino-2-pyrazinecarboxylate(3) affords the synthetically useful 3-aroylaminopyrazin-2-carboxylates 5a-f with aroyl chlorides, which are converted with dibromotriphenylphosphorane into 2-arylpyrazino[2,3-d][3,1]oxazin-4-ones 6a-f. Nucleophilic attack at the carbonyl function of these oxazinones results in ring cleaved amides which can be recyclized with dibromotriphenylphosphorane to afford 2-arylpteridin-4-ones 7a-f.