Synthesis of aryl 2‐(2‐imidazolyl)ethyl ketones

Aryl 2‐[(2‐imidazolyl)ethyl or 3‐(2‐imidazolyl)propyl]ketones were ketalized by glycerol or 3‐mercapto‐1,2‐propanediol in boiling benzene in the presence of 4‐toluenesulfonic acid to provide the title compounds. The aryl substituents are 4‐chloro‐, 4‐bromo‐, 4‐fluoro‐, or 2,4‐dichlorophenyl. While aryl (2‐imidazolyl)methyl ketones condensed with glycerol to form cis‐ and trans‐{2‐aryl‐2‐[(2‐imidazolyl)methyl]‐4‐(hydroxymethyl)}‐1,3‐dioxolanes, related condensations with 3‐mercapto‐1,2‐propanediol, under similar, or even more stringent reaction conditions, produced no 1,3‐oxathiolane analogs, with the starting ketones being recovered. Separation and structure determination of these racemic cis and trans isomeric products are described. The structure of these stereoisomers was established by means of 1H and 13C nmr correlation and nOe experiments. Selective methylation of the N‐unsubstituted 2‐imidazolyl alcohols with one equivalent sodium hydride and methyl iodide provided the corresponding N‐methyl alcohols in excellent yields. With excess benzoyl chloride, N‐unsubstituted 2‐imidazolyl alcohols were initially converted to O, N‐dibenzoates from which the N‐benzoyl group was easily cleaved by ammonium hydroxide in ethanol to provide benzoate esters.

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Synthesis of 1‐halophenyl 4‐(2‐imidazolyl)‐1‐butanones and 5‐(2‐imidazolyl)‐1‐pentanones and their ketalization with glycerol

Huang¹,

Bauer²

1997

Journal of Heterocyclic Chem

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An alternate synthesis of 1‐(2,4‐dichlorophenyl)‐4‐(2‐imidazolyl)‐1‐butanones 5d is presented after 1‐[(dimethylamino)methyl‐ and 1‐methyl]‐2‐lithioimidazole failed to be substituted satisfactorily by 2‐(2,4‐dichlorophenyl)‐2‐(3‐iodopropyl)‐1,3‐dioxolane (3b). The Pinner addition of ethanol to 2‐(2,4‐dichlorophenyl)‐2‐(3‐cyanopropyl)‐1,3‐dioxolane yielded the corresponding imidate which was reacted with 1‐amino‐2,2‐dimethoxyethane to form an amidine. Hot dilute hydrochloric acid converted this ami‐dine to the 2‐imidazolyl ketone 5b. Syntheses of homologous 1‐(4‐chloro‐ and 2,4‐dichlorophenyl)‐4‐(2‐imidazolyl)‐1‐pentanones 20 are described. Ketalizations of 5 and 20 with glycerol formed imidazolyl 1,3‐dioxolanyl alcohols. Selective N‐ and O‐alkylations of some of these imidazolyl alcohols are described.

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Synthesis of aryl 2‐(2‐imidazolyl)ethyl ketones

Cited by 7 publications

References 12 publications

ChemInform Abstract: Synthesis of Aryl 2‐(2‐Imidazolyl)ethyl Ketones.

ChemInform Abstract: Synthesis of Aryl 2‐(2‐Imidazolyl)ethyl Ketones.

Ketalizations of aryl ω‐(2‐imidazolyl)alkyl ketones by glycerol and 3‐mercapto‐1,2‐propanediol. synthesis and characterization of cis‐ and trans‐{2‐aryl‐2‐[ω‐(2‐imidazolyl)alkyl](1,3‐dioxolan‐4‐yl and 1,3‐oxathiolan‐5‐yl)}methanols

Synthesis of 1‐halophenyl 4‐(2‐imidazolyl)‐1‐butanones and 5‐(2‐imidazolyl)‐1‐pentanones and their ketalization with glycerol

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