Three-Component Reaction of 1,3,4,6-Tetraketones with Acetone and Amines
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Three-Component Reaction of 1,3,4,6-Tetraketones with Acetone and Amines A. R. Galeeva, I. G. Mokrushina, M. V. Dmitrieva, and A. N. Maslivetsa,* a
Perm State University, Perm, 614990 Russia *e-mail: [email protected]
Received March 17, 2020; revised March 22, 2020; accepted March 26, 2020
Abstract—1,6-Diarylhexane-1,3,4,6-tetraones reacted with 2-aminophenol and acetone according to previously unknown pathway leading to the formation of 3-aryl-3-hydroxy-1-{5-[(2-hydroxyphenyl)amino][1,1′-biphenyl]3-yl}prop-2-en-1-ones. Similar three-component reactions with benzylamine or 2-methoxyaniline afforded mainly 2-(4-aroyl-3-hydroxy-5,5-dimethyl-1,5-dihydro-2H-pyrrol-2-ylidene)-1-arylethan-1-ones. Keywords: multicomponent reactions, 1,3,4,6-tetracarbonyl compounds, anilines, acetone, dihydropyrroles
DOI: 10.1134/S1070428020070295 1,3,4,6-Tetracarbonyl compounds are used in the synthesis of heterocycles [1–5]; however, multicomponent reactions with 1,3,4,6-tetracarbonyl compounds have been poorly studied. In particular, polysubstituted pyrroles and dihydropyrroles were obtained by reacting 1,3,4,6-tetracarbonyl compounds with p-toluidine and benzaldehyde or acetone [6–8]. We previously reported the synthesis of meta-substituted anilines by threecomponent reaction of acetone with amines and electron-deficient 1,3-diketones [9]. Herein, we describe the three-component reaction of acetone with 1,6-diarylhexane-1,3,4,6-tetraones and amines. 1,6-Diarylhexane-1,3,4,6-tetraones 1a and 1b reacted with 2-aminophenol in acetone in the presence of 4-Å molecular sieves and a catalytic amount of acetic acid at 55°C (4–10 h) to give 3-aryl-3-hydroxy-1-{5[(2-hydroxyphenyl)amino][1,1′-biphenyl]-3-yl}prop-2en-1-ones 2a and 2b (Scheme 1). The structure of the products was confirmed by X-ray analysis of 2a (Fig. 1). A plausible reaction mechanism involves initial formation of enamine by condensation of acetone with 2-aminophenol, attack of the enamine on C3 of tetraketone 1, and intramolecular cyclization. The reactions of tetraketones 1a–1c with benzylamine and 2-methoxyaniline in acetone under similar conditions followed a different pathway [7, 8], and the products were 2-(4-aroyl-3-hydroxy-5,5-dimethyl-1,5dihydro-2H-pyrrol-2-ylidene)-1-arylethan-1-ony 4a– 4c. Their structure was proved by the X-ray diffraction
data for compound 4a (Fig. 2). Presumably, acetone imine is attacked by the enol fragment of tetraketone 1, followed by intramolecular cyclization. The described reaction of tetraketones with acetone and 2-aminophenol is a novel transformation of 1,3,4,6-tetracarbonyl compounds, which was observed only for 2-aminophenol. In most cases, similar reactions with 2-aminoethanol, benzylamine, cyclohexylamine, 2-methoxyaniline, and aniline led to the formation of complex mixtures of products, where dihydropyrroles 4 predominated, whereas aniline derivatives like 2 were formed in minor amounts (according to the HPLC/MS data). (Z)-3-Hydroxy-1-{5-[(2-hydroxyphenyl)amino][1,1′-biphenyl]-3-yl}-3-phenylprop-2-en-1-one (2a). A roun
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