SYNTHESIS OF BENZOFURAN DERIVATIVES ON THE BASIS OF N-ACYL-1,4-BENZOQUINONE MONOIMINES

Abstract

Earlier it was found the structure of the reaction products of 1,4-benzoquinones and N-arylsulfonyl-1,4-benzoquinone monoimines with acetylacetone imines depends on the structure of the reagents and the experimental conditions. The indole derivatives formed in aprotic solvents, the benzofuran derivatives were obtained in acidic medium. Benzofuran derivatives are bioactive compounds and widely used as drugs. The aim of this work is to obtain reaction products of new N-acyl-1,4-benzoquinone monoimines with 4-(4-toluidine)pent-3-en-2-one. Reactions of N-aroyl-, N-benzylideneacetyl-, N-arylaminocarbonyl-1,4-benzoquinone monoimines with 4-(4-toluidine)pent-3-en-2-one were carried out in acetic acid, chloroform and dichloroethane with distillation of the solvent. The new 3-acetyl-5-acylamido-2-methylbenzofurans were obtained in one step at room temperature only in acetic acid. The Nenitescu reaction is multistage and the presence of protons in the reaction medium greatly facilitates a protonation of intermediates formed during reaction. The reaction products were obtained only for quinone imines with a free C=C bond in the quinoid ring. For 2,5-dimethyl-, 6-isopropyl-3-methyl-, 3,5-dimethyl derivatives of 1,4-benzoquinone monoimines, containing alkyl substituents at the carbon atoms of both C=C bonds of the quinoid ring, we obtained mixtures of products which could not be identified. We did not obtain indole derivatives, since the reaction of N-aroyl-, N-benzylideneacetyl-, N-arylaminocarbonyl-1,4-benzoquinone monoimines with 4-(4-toluidine)pent-3-en-2-one in aprotic solvents gave multicomponent mixtures which could not be separated.

Keywords

• 3-ацетил-5-ациламідо-2-метилбензофуран
• 4-(п-толуїдино)пент-3-ен-2-он
• реакція Неніцеску
• N-ацил-1,4-бензохінонмоноіміни