Thiourea-catalysed ring opening of episulfonium ions with indole derivatives by means of stabilizing non-covalent interactions.
Thiourea-catalysed ring opening of episulfonium ions with indole derivatives by means of stabilizing non-covalent interactions.
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小的有机和含金属分子（分子量<1，000）可以催化合成有用的反应，具有通常与大分子酶催化剂相关的高水平立体选择性。尽管酶通常被理解为加速反应并赋予选择性，因为它们通过协同相互作用的网络稳定特定的过渡结构，但手性小分子催化剂的对映选择性通常通过除一种主导途径外的所有途径的空间不稳定来合理化。然而，越来越明显的是，稳定作用在小分子催化中也起着重要的作用，尽管这种系统的机械特性是罕见的。在这里，我们表明，芳基吡咯烷酰氨基硫脲催化剂催化的对映选择性的亲核开环episulfonium离子的吲哚。在速率和选择性确定步骤中，硫脲催化剂对主要途径的选择性过渡态稳定提供了证据。对映体选择性是通过催化剂和过渡结构组装中的反应组分之间的吸引性阴离子结合、阳离子-π和氢键相互作用的网络来实现的。
Small organic and metal-containing molecules (molecular mass <1,000) can catalyse synthetically useful reactions with the high levels of stereoselectivity typically associated with macromolecular enzymatic catalysts. Whereas enzymes are generally understood to accelerate reactions and impart selectivity as they stabilize specific transition structures through networks of cooperative interactions, enantioselectivity with chiral, small-molecule catalysts is rationalized typically by the steric destabilization of all but one dominant pathway. However, it is increasingly apparent that stabilizing effects also play an important role in small-molecule catalysis, although the mechanistic characterization of such systems is rare. Here, we show that arylpyrrolidino amido thiourea catalysts catalyse the enantioselective nucleophilic ring opening of episulfonium ions by indoles. Evidence is provided for the selective transition-state stabilization of the major pathway by the thiourea catalyst in the rate- and selectivity-determining step. Enantioselectivity is achieved through a network of attractive anion binding, cation-πand hydrogen-bond interactions between the catalyst and the reacting components in the transition-structure assembly.
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影响因子：
15
作者：
Brown, Adam R.;Kuo, Wen-Hsin;Jacobsen, Eric N.
通讯作者：
Jacobsen, Eric N.
影响因子：
15
作者：
Denmark, Scott E.;Collins, William R.;Cullen, Matthew D.
通讯作者：
Cullen, Matthew D.
影响因子：
15
作者：
Fachini, M;Lucchini, V;Pasquato, L
通讯作者：
Pasquato, L
DOI：
10.1126/science.1188403
发表时间：
2010-06-04
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Gustafson JL;Lim D;Miller SJ
通讯作者：
Miller SJ
影响因子：
15
作者：
Gal, JF;Maria, PC;Abboud, JLM
通讯作者：
Abboud, JLM