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首页> 外文期刊>Journal of the Chemical Society, Perkin Transactions 1 >Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(I)-mediated reactions with dicyclohexylcarbodiimide
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Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(I)-mediated reactions with dicyclohexylcarbodiimide

机译：通过酸催化的由铜（I）介导的反应形成的单异脲的环化反应，将（Z）-1,4-二羟基烷-2-烯转化为2,5-二氢呋喃，将烷烃1,4-二醇转化为四氢呋喃与二环己基碳二亚胺

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2,5-Dihydrofurans 1 are an important class of compounds, thensynthesis of which has received considerable attention. Fornexample, Heck arylation or vinylation of 2,3-dihydrofurans,1nring-closing metathesis reactions of diallyl ethers,2 retro-nDiels–Alder reactions of modified furan–2,5-dihydrofuranncycloadducts,3 Wittig cyclo-olefination reactions of suitablenβ-oxaethylphosphoranes 4 and selenyl halide-induced cyclisationsnof α-allenic alcohols 5 have all been utilised for thisnpurpose.nThe dehydrative cyclisation of (Z)-1,4-dihydroxyalk-2-enes 2nto give 2,5-dihydrofurans 1 is, in principle, a simple and attractivensynthetic route to these compounds. However, this type ofncyclisation is usually effected under relatively harsh acidic conditions.nThus, treatment with sulfuric acid succeeds for somencases 6 but may also lead to the formation of polymers,7 and itnfrequently causes acid-catalysed dehydration of the diols 2 sonthat variable amounts of α,β-unsaturated carbonyl compoundsnare also produced.8nReaction of (Z)-1,4-dihydroxybut-2-ene 2a with the diaryldialkoxysulfanen3 has been reported 9 to give 2,5-dihydrofurannin 84% yield, but the reagent is expensive. Diethoxytriphenylphosphoranen4 efficiently cyclises the same diol 10 but thisnreagent must be prepared from explosive diethyl peroxide. Thenenvironmentally toxic butyltrichlorotin reacts with the diol 2anto give 2,5-dihydrofuran (88%) together with some crotonaldehyde.n11 Barry and Evans have described 12,13 how (Z)-1,4-dihydroxybut-n2-ene 2a can be cyclised in the presence of eitherntert-BuOCl–Ph3P–K2CO3 or Ph3P–CCl4 to give 2,5-dihydrofurannin >60% yields.n† Electronic supplementary information (ESI) available. Experimentalndata for compounds 14a–f, 15a–f, 7a–f, 22a–g, 21a–e and 2b–e: Seenhttp://www.rsc.org/suppdata/p1/b2/b203389pIn connection with other work,14 we needed reliable access ton5-(2u0001,5u0001-dihydro-2u0001-furyl)pentanoic acid 5, and attempted tonmake this compound as its methyl ester 6c via cyclodehydrationnof the (Z)-diol 7c using each of the methodologies describednby Barry and Evans. In the event, treatment of 7c with eithernof their reagent combinations led to unsatisfactory yieldsn(25–30%) of the dihydrofuran 6c. Accordingly, we sought tondevelop a more effective method for this transformation.
机译：2,5-二氢呋喃1是一类重要的化合物，其合成受到了广泛的关注。例如，2,3-二氢呋喃的Heck芳基化或乙烯基化，1，二烯丙基醚的环合复分解反应，2，retro-nDiels-修饰的呋喃-2,5-二氢呋喃环加合物的Alder反应，3合适的β-氧杂乙基正膦酸酯的维蒂希环烯化反应4为此，α-烯醇5的卤代环和硒烯基卤化物诱导的环化均已用于该目的。（Z）-1,4-二羟基烷-2-烯2的脱水环化生成2,5-二氢呋喃1原则上是简单的和吸引人的途径合成这些化合物。但是，这种类型的环化通常是在相对苛刻的酸性条件下进行的。因此，在某些情况下，用硫酸处理成功6，但也可能导致聚合物的形成7，因此常常引起酸催化的二醇的脱水2，因此，还报道了α，β-不饱和羰基化合物的生成。[8n]据报道9（（Z）-1,4-二羟基丁-2-烯2a与二芳基二烷氧基硫丹3的反应可产生84％的2,5-二氢呋喃宁，但该试剂价格昂贵。二乙氧基三苯基磷杂环丁烷4可有效地环化相同的二醇10，但该试剂必须由易爆的过氧化二乙基制备。然后，具有环境毒性的丁基三氯锡与二醇2发生反应，生成2,5-二氢呋喃（88％）和一些巴豆醛。n11Barry和Evans描述了12,13如何将（Z）-1,4-dihydroxybut-n2-ene 2a环化在存在ntert-BuOCl–Ph3P–K2CO3或Ph3P–CCl4的情况下，可以得到> 60％的2,5-二氢呋喃宁。n†提供电子补充信息（ESI）。化合物14a-f，15a-f，7a-f，22a-g，21a-e和2b-e的实验数据：参见http://www.rsc.org/suppdata/p1/b2/b203389p与其他工作相关[14]，我们需要可靠地获得ton5-（2u0001,5u0001-dihydro-2u0001-furyl）pentanoic acid 5，并尝试使用Barry和Barn所描述的每种方法，通过（Z）-二醇7c的环脱水作用，将该化合物制成其甲酯6c。埃文斯结果，用它们的任何一种试剂组合处理7c都会导致二氢呋喃6c的产率n（25–30％）不令人满意。因此，我们寻求为这种转化开发更有效的方法。

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