Enantioselective, cyclopentene-forming annulations via NHC-catalyzed benzoin-oxy-cope reactions
Enantioselective, cyclopentene-forming annulations via NHC-catalyzed benzoin-oxy-cope reactions
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DOI：
10.1021/ja0705543
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发表时间：
2007-03-28
影响因子：
15
通讯作者：
Bode, Jeffrey W.
中科院分区：
文献类型：
--
作者：
Chiang, Pei-Chen;Kaeobamrung, Juthanat;Bode, Jeffrey W.
由三唑盐制备的手性n -杂环羰基催化剂促进α、β -不饱和醛和4-氧烯酸酯形成环戊烯，具有优异的对映诱导水平，并且偏爱顺式-1,3,4-三取代环戊烯非对映体。虽然观察到的产物可能是由催化生成的同烯醇酯的共轭加成而产生的，但我们的机理和立体化学研究强烈支持一种新的反应流形，其特征是分子间交叉苯甲酸反应和nhc催化的氧- cope重排。
Chiral N-heterocyclic carbene catalysts generated from triazolium salts promote the cyclopentene-forming annulation of alpha,beta-unsaturated aldehydes and 4-oxoenoates with excellent levels of enantioinduction and preference for the cis-1,3,4-trisubstituted cyclopentene diastereomer. Although the observed products could arise by conjugate additions of catalytically generated homoenolates, our mechanistic and stereochemical investigations strongly support a novel reaction manifold featuring an intermolecular crossed-benzoin reaction and an NHC-catalyzed oxy-Cope rearrangement.