Iodine(III) Derivatives as Halogen Bonding Organocatalysts
Iodine(III) Derivatives as Halogen Bonding Organocatalysts
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DOI：
10.1002/anie.201713012
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发表时间：
2018-03-26
影响因子：
16.6
通讯作者：
Huber, Stefan M.
中科院分区：
文献类型：
--
作者：
Heinen, Flemming;Engelage, Elric;Huber, Stefan M.
高价碘（III）衍生物是有机合成中的通用试剂，但关于其作为刘易斯酸性有机催化剂的应用，以前只有一篇报道。在此，我们提出了第一个强有力的迹象，卤素键合在这类催化剂中的关键作用。为此，二苯甲基氯的溶剂分解和环戊二烯与甲基乙烯基酮的Diels-Alder反应作为卤化物提取和中性化合物活化的基准反应。碘化合物（环状二芳基碘鎓类）被用作活化剂或催化剂，我们能够显着降低或完全关闭其活性的空间阻断其亲电轴的一个或两个。与先前建立的双齿阳离子卤素键供体相比，本文所用的单齿有机碘衍生物具有至少类似的活性（在Diels-Alder反应中）或甚至明显更高的活性（在二苯甲基氯溶剂分解中）。
Hypervalent iodine(III) derivatives are known as versatile reagents in organic synthesis, but there is only one previous report on their use as Lewis acidic organocatalysts. Herein, we present first strong indications for the crucial role of halogen bonding in this kind of catalyses. To this end, the solvolysis of benzhydryl chloride and the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone served as benchmark reactions for halide abstraction and the activation of neutral compounds. Iodolium compounds (cyclic diaryl iodonium species) were used as activators or catalysts, and we were able to markedly reduce or completely switch off their activity by sterically blocking one or two of their electrophilic axes. Compared with previously established bidentate cationic halogen bond donors, the monodentate organoiodine derivatives used herein are at least similarly active (in the Diels-Alder reaction) or even decidedly more active (in benzhydryl chloride solvolysis).