Králová P, Maloň M, Koshino H, Soural M. Convenient Synthesis of Thiohydantoins, Imidazole-2-thiones and Imidazo[2,1-
b]thiazol-4-iums from Polymer-Supported α-Acylamino Ketones.
Molecules 2018;
23:molecules23040976. [PMID:
29690582 PMCID:
PMC6017016 DOI:
10.3390/molecules23040976]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 04/18/2018] [Accepted: 04/20/2018] [Indexed: 11/16/2022] Open
Abstract
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.
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