Thiazole C-nucleosides. III. Synthesis of pyranose analogues of tiazofurin
作者:Lajos Kovács、Pál Herczegh、Gyula Batta、István Farkas
DOI:10.1016/s0040-4020(01)80985-6
日期:1991.7
5-tri-0-acetyl-2,6-anhydro-L-mannono-and-D-gulonothioamides (5, 6) has been achieved from the corresponding nitriles. The Hantzsch reaction of (5) or (6) with ethyl bromopyruvate afforded the expected thiazoles (7.8) only in a low yield along with furan derivatives (9-11), the formation of which is rationalized by an acid-catalysed rearrangement-elimination process. The some Hantzsch reaction in the presence
从相应的腈类已经实现了3,4,5-三-0-乙酰基-2,6-脱水-L-甘露糖基-和-D-古洛糖基硫酰胺的大规模合成(5,6)。(5)或(6)与溴丙酮酸乙酯的Hantzsch反应仅以低收率提供了预期的噻唑(7.8)以及呋喃衍生物(9-11),其形成通过酸催化重排消除而合理化过程。在碳酸钡存在下的一些Hantzsch反应产生羟基噻唑啉(16,17)。试图脱水(16)或(17)与三氟乙酸酐或三氟乙酸酐/吡啶形成pent-1'-enopyranosylthiazoles(18-20)。脱保护的硫代酰胺(24,25),配有溴丙酮酸乙酯噻唑(27,28)。将所获得的噻唑酯(7,8,18-20。27,28)转化到新噻唑呋林类似物(12,13,21-23)。