Esters of amino acids were reacted with 2-cyano-4-nitrobenzenesulfonyl chloride or 2-cyano-4-(trifluoromethyl)benzenesulfonyl chloride and alkylated with various α-haloketones. The corresponding sulfonamides were heated in a solution of ammonium acetate, which yielded imidazo[2,1-a]isoindolones in one step. The key reaction was based on intramolecular C-arylation followed by spontaneous cycloaddition and cyclocondensation. Two approaches have been developed: (i) solid-phase synthesis starting from amino acids immobilized on Wang resin, which allows the rapid preparation of target compounds using the cyclative cleavage strategy, and (ii) traditional solution-phase synthesis using amino acid methyl esters as the starting materials. The advantages and drawbacks of both alternatives are compared.

• Publikační typ
• časopisecké články MeSH

The preparation of 5-methylene-thiohydantoins using solid-phase synthesis is reported in this paper. After sulfonylation of immobilized Ser (t-Bu)-OH with 4-nitrobenzenesulfonyl chloride followed by alkylation with various bromoketones, the 4-Nos group was removed and the resulting polymer-supported α-acylamino ketones reacted with Fmoc-isothiocyanate. Cleavage of the Fmoc protecting group was followed by the spontaneous cyclative cleavage releasing the 5-methylene-thiohydantoin derivatives from the polymer support. Reduction with triethylsilane (TES) yielded the corresponding 5-methyl-thiohydantoins. When Fmoc-isothiocyanate was replaced with alkyl isothiocyanates, the trifluoroacetic acid (TFA) mediated cleavage from the polymer support, which was followed by the cyclization reaction and the imidazo[2,1-b]thiazol-4-iums were obtained. Their conversion in deuterated dimethylsulfoxide led to imidazole-2-thiones.

• Klíčová slova
• bromoketone, heterocycle, imidazole, serine, solid-phase synthesis, thiohydantoin,
• MeSH
• ketony chemie   MeSH
• polymery chemie   MeSH
• stereoizomerie MeSH
• techniky syntézy na pevné fázi MeSH
• thiohydantoiny chemická syntéza   chemie   MeSH
• thioketony chemická syntéza   chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ketony MeSH
• polymery MeSH
• thiohydantoiny MeSH
• thioketony MeSH