The hexadehydro-Diels-Alder reaction: a new chapter in aryne chemistry.
The hexadehydro-Diels-Alder reaction: a new chapter in aryne chemistry.
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DOI：
10.1002/anie.201402405
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发表时间：
2014-06-02
影响因子：
16.6
通讯作者：
Greaney, Michael F.
中科院分区：
文献类型：
--
作者：
Holden Nee Hall, Catherine;Greaney, Michael F.
芳烃继续在芳香族化学中激发新的反应和理论见解。近年来，由于2-(三甲基硅基)苯基三氟酸酯(1)作为邻苯的前体具有特殊的多功能性而推动了这一进展。[1]这些化合物在温和的条件下反应，使芳烃化学在经典转化(亲核加成、周环反应)和开辟新领域，如σ插入反应和过渡金属催化过程方面都有了长足的发展。与迄今为止生成邻苯并炔的所有方法一样，化合物1需要从预先存在的芳烃中移除两个相邻的基团。最近来自Hoye和Lee的小组的工作利用了一种完全不同的方法来研究邻芳烃，该方法通过三炔3的分子内环加成进行(方案1)。[2，3]这种转化被Hoye称为六氢Diels-Alder(HDDA)反应，类似于其他脱氢周环反应，乍一看可能令人惊讶，因为很少有人描述芳烃共振结构4，它直接来自[4+2]环加成。以这种方式生成的邻苯基中间体的捕获可以通过各种分子间和分子内的转化来完成，从而提供了获得有价值的苯类化合物的新方法。HDDA反应的起源来自1997年Johnson和Ueda两个独立的报告。[4]Johnson和他的同事们将简单的烃1，3，8-二十三炔(6)进行闪速真空热解，能够以95%的总收率分离吲哚和吲烯(方案1c)。[4A]最可能的机理似乎是[4+2]环加成生成芳烃，然后在热解条件下还原。氚标记研究支持这一机制，排除了可能的1，2-Shift/Bergman环化途径。对乙炔与丁二炔的环加成反应的密度泛函计算给出了令人惊讶的结果，即通过HDDA反应生成苯炔的反应将是高度放热的(±52千卡摩尔±1)，并伴随着很大的自由活化能(37千卡摩尔±1)。[4C]上田小组观察到，在室温下，四炔类化合物如9可以环化成5H-荧烯醇衍生物，并通过分子内和分子间捕获实验(例如，得到10)确定了邻苯并炔物种的中间体。[4B]上田及其同事继续研究HDDA反应的范围，并建立了与氧、硫和氮的亲核剂的分子内捕获反应。在螺旋多烯合成领域和以这种方式生成的邻位芳烃的DNA裂解性能的研究中展示了应用。[5]与Bergman和Myers-Saito环芳构化反应有明显的相似之处，DNA链的裂解类似于对苯二炔
Arynes continue to stimulate new reactions and theoretical insight in aromatic chemistry. This has been driven in recent years by the exceptional versatility of 2-(trimethylsilyl) phenyl triflate (1) as a precursor to ortho-benzyne.[1] Such compounds react under mild conditions and have enabled a substantial development of aryne chemistry both in terms of classical transformations (nucleophilic addition, pericyclic reactions) and in opening up new areas, such as σ-insertion reactions and transition-metal-catalyzed processes. As with all methods for the generation of ortho-benzyne to date, compound 1 requires the removal of two adjacent groups from a pre-existing arene. Recent work from the groups of Hoye and Lee has utilized a completely different approach to ortho-arynes, which proceeds through the intramolecular cycloaddition of triynes 3 (Scheme 1).[2, 3] This transformation, which was termed a hexadehydro-Diels–Alder (HDDA) reaction by Hoye in analogy to other dehydropericyclic reactions, is perhaps surprising at first glance because of the infrequently depicted aryne resonance structure 4, which immediately arises from the [4+ 2] cycloaddition. The trapping of an ortho-benzyne intermediate generated in this fashion can then be accomplished by a variety of inter-and intramolecular transformations, affording new approaches to valuable benzenoid compounds. The origin of the HDDA reaction lies in two independent reports from the groups of Johnson and Ueda in 1997.[4] Johnson and co-workers subjected the simple hydrocarbon 1, 3, 8-nonatriyne (6) to flash vacuum pyrolysis and were able to isolate indane and indene in a combined yield of 95%(Scheme 1 c).[4a] The most likely mechanism appeared to be a [4+ 2] cycloaddition to form an aryne, followed by reduction under the pyrolytic conditions. Deuterium labeling studies support this mechanism, ruling out a possible 1, 2-shift/Bergman cyclization pathway. DFT calculations for the cycloaddition of acetylene with butadiyne gave the surprising result that the formation of benzyne through an HDDA reaction would be highly exothermic (À52 kcal molÀ1) and accompanied by a large free energy of activation (37 kcal molÀ1).[4c]The Ueda group observed that tetraynes such as 9 could cyclize to 5H-fluorenol derivatives at room temperature, with the intermediacy of an ortho-benzyne species being established by intra-and intermolecular trapping experiments (to give 10, for example).[4b] Ueda and co-workers then continued to investigate the scope of the HDDA reaction and established intramolecular trapping reactions with oxygen, sulfur, and nitrogen nucleophiles. Applications were demonstrated in the areas of helical polyene synthesis and in studies on the DNA-cleaving properties of the ortho-aryne generated in this fashion.[5] The similarities to the Bergman and Myers–Saito cycloaromatization reactions are evident, and cleavage of the DNA strands, analogous to the en–diyne para-benzyne
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影响因子：
21.8
作者：
通讯作者：
--
影响因子：
1.8
作者：
Miyawaki, K;Kawano, T;Ueda, I
通讯作者：
Ueda, I
影响因子：
1.8
作者：
Miyawaki, K;Suzuki, R;Ueda, I
通讯作者：
Ueda, I
影响因子：
15
作者：
Im, G-Yoon J.;Bronner, Sarah M.;Goetz, Adam E.;Paton, Robert S.;Cheong, Paul H-Y;Houk, K. N.;Garg, Neil K.
通讯作者：
Garg, Neil K.
影响因子：
5.2
作者：
Niu, Dawen;Wang, Tao;Woods, Brian P.;Hoye, Thomas R.
通讯作者：
Hoye, Thomas R.