A Facile Synthesis of 2-Substituted 2,3-Dihydro-4(1H)-azuleno[1,2-d]pyrimidinones

Abstract

A facile, efficient and novel approach to access 2-substituted 2,3-dihydro-4(1H)-azuleno [2,1-d]pyrimidinones was developed by condensation of methyl 2-amino-3-carbamoylazulene-1-carboxylate with ketones or ary1 aldehydes in the 2,2,2-trifluoroethanol catalyzed by p-toluenesulfonic acid.2][3][4] In a previous paper, we reported that 1-acetyl-2-(bromomethyl)azulene reacted with anilines or thio-acetamide to give 2-aryl-3-methylazuleno[1,2-c]pyrroles 5 or azuleno[1,2-c]thiophenes 6 respectively.Of them, pyrimidine-fused azulenes were prepared by using different types of stating materials as followings. 2-Amino-1-formylazulene reacted with guanidine to convert to 2-aminoazuleno[2,1-d]pyrimidine. 7When the reaction of 2-acetylimino-2H-cyclohepta[b]furan derivatives with active methylene compounds to afford the azuleno[2,1-d]pyrimidine derivatives. 8Quite recently, we have reported the synthesis of