Reinvestigation of the sulfuric acid-catalysed cyclisation of brominated 2-alkyllevulinic acids to 3-alkyl-5-methylene-2(5H)-furanones
Reinvestigation of the sulfuric acid-catalysed cyclisation of brominated 2-alkyllevulinic acids to 3-alkyl-5-methylene-2(5H)-furanones
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DOI：
10.1016/s0040-4020(97)10034-5
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发表时间：
1997-11-17
期刊：
影响因子：
2.1
通讯作者：
Steinberg, P
中科院分区：
文献类型：
--
作者：
Manny, AJ;Kjelleberg, S;Steinberg, P
描述了由烷基取代的乙酰丙酸衍生物通过溴化和酸促进的内酯化反应合成乙基-、丁基-、己基-和十二烷基-取代的溴内酯。以乙酰丙酸为模型，研究了溴化反应的机理，讨论了溴化反应条件和酸浓度对产物分布的影响。二溴化在CHCl3中进行得最好，在不含EtOH的CHCl3中进行，没有酯形成的复杂性。在98 - 100%H2SO4中伴随氧化发生环化，但在100%H2SO4中得到最高产率的fimbrolides。还描述了相关贝克雷来物质的形成。(C)1997 Elsevier Science Ltd.
A synthesis of ethyl-, butyl-, hexyl- and dodecyl-substituted fimbrolides from alkyl-substituted levulinic acid derivatives through bromination and acid promoted lactonisation is described. The underlying reactions have been investigated using levulinic acid as a model, and the effects of varying the bromination conditions and changing acid concentration on product distribution are discussed. Dibromination proceeds best in CHCl3 and proceeds in EtOH-free CHCl3 without the complication of ester formation. Cyclisation occurs with concomitant oxidation in 98-100% H2SO4 but gives highest yields of fimbrolides in 100% H2SO4. The formation of related beckerelide substances is also described. (C) 1997 Elsevier Science Ltd.