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首页> 外文期刊>Nature >Antibody catalysis of a reaction otherwise strongly disfavoured in water.
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Antibody catalysis of a reaction otherwise strongly disfavoured in water.

机译：反应的抗体催化在水中强烈不利。

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摘要

Several examples have been reported recently of antibody catalysis of reactions that are strongly disfavoured because of the high free energy of the transition state. Here we show that catalytic antibodies can be used to promote a particularly useful kind of reaction from a synthetic point of view: one involving an intermediate that is highly unstable in water. We show that an antibody elicited against the quaternary ammonium ion 4a (Fig. 1) catalyses the protonation of the enol ether 1 to form, with complete enantioselectivity, an oxocarbonium intermediate. This species is highly reactive in water, and would normally react with a water molecule to give the corresponding ketone 2. But the antibody provides a hydrophobic environment that allows the oxocarbonium ion instead to undergo an intramolecular reaction to form an enantiomerically pure ketal 3. This result shows that catalytic antibodies can exclude solvent molecules entirely from crucial steps on the reaction pathway.
机译：最近已经报道了由于过渡态的高自由能而强烈反对反应的抗体催化的几个例子。从合成的角度来看，我们显示出催化性抗体可用于促进一种特别有用的反应：一种涉及在水中高度不稳定的中间体。我们表明，针对季铵离子4a（图1）引发的抗体催化烯醇醚1的质子化，形成具有完全对映选择性的氧碳中间体。这种物质在水中具有高反应性，通常会与水分子反应生成相应的酮2。但是该抗体提供了疏水性环境，允许氧碳鎓离子进行分子内反应以形成对映体纯的缩酮3。结果表明，催化抗体可以将溶剂分子完全排除在反应路径的关键步骤之外。

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