The preparation of 5-methylene-thiohydantoins using solid-phase synthesis is reported\nin this paper. After sulfonylation of immobilized Ser (t-Bu)-OH with 4-nitrobenzenesulfonyl\nchloride followed by alkylation with various bromoketones, the 4-Nos group was removed and\nthe resulting polymer-supported �±-acylamino ketones reacted with Fmoc-isothiocyanate. Cleavage\nof the Fmoc protecting group was followed by the spontaneous cyclative cleavage releasing the\n5-methylene-thiohydantoin derivatives from the polymer support. Reduction with triethylsilane\n(TES) yielded the corresponding 5-methyl-thiohydantoins. When Fmoc-isothiocyanate was replaced\nwith alkyl isothiocyanates, the trifluoroacetic acid (TFA) mediated cleavage from the polymer support,\nwhich was followed by the cyclization reaction and the imidazo[2,1-b]thiazol-4-iums were obtained.\nTheir conversion in deuterated dimethylsulfoxide led to imidazole-2-thiones.
Loading....