2-Protecting groups for 5-lithiation in the syntheses of imidazoles
2-Protecting groups for 5-lithiation in the syntheses of imidazoles
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咪唑合成中 5-锂化的 2-保护基团
DOI：
10.1039/p19900001645
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
R. Ngochindo
中科院分区：
文献类型：
--
作者：
R. Ngochindo
基于咪唑-2-羧酸易于脱羧和C（2）-Si键断裂的特点，考察了各种取代基在咪唑合成中作为有机锂试剂的2-保护基的可能性。在2-位的叔酰胺基官能团和叔丁基二甲基甲硅烷基（TBDMS）基团允许N-取代的咪唑的定量5-锂化。酰胺基官能团的脱保护发生在碱性条件下，而TBDMS基团被几种试剂除去。TBDMS取代基在高达-10 °C的温度下对丁基锂稳定。
Various substituents have been examined as possible 2-protecting groups against organolithium reagents in the syntheses of imidazoles on the basis of the ease of decarboxylation of imidazole-2-carboxylic acids and cleavage of the C(2)–Si bond. The tertiary amido function and t-butyldimethylsilyl (TBDMS) group at the 2-position permit quantitative 5-lithiation of N-substituted imidazoles. Deprotection of the amido function occurs under alkaline conditions while the TBDMS group is removed by several reagents. The TBDMS substituent is stable to butyl-lithium at temperatures up to –10 °C.