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首页> 外文期刊>Chemistry: A European journal >A Closer Look at Spontaneous Mirror Symmetry Breaking in Aldol Reactions
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A Closer Look at Spontaneous Mirror Symmetry Breaking in Aldol Reactions

机译：仔细研究Aldol反应中自发镜像对称性的破坏

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The aldol reaction between acetone and 4-nitrobenzaldehyde run in the nominal absence of any enantioselective catalyst was monitored by chiral HPLC with the aid of an internal standard. The collected data show the presence of a detectable initial enantiomeric excess of the aldol product in the early stages of the reaction in about 50% of the experiments. Only a small fraction of the reaction contained the non-racemic aldol product after 24 h. This temporary emergence of natural optical activity could be the signature of a coupled reaction network that leads to a spontaneous mirror-symmetry-breaking process, which originates at very low conversions (i.e., strongly depends on events taking place at the very first stages of the process). The reaction is not autocatalytic in the aldol product, which rules out a simple Frank-type reaction network as the source of the observed symmetry breaking. On the other hand, the isolation and characterisation of a double-aldol adduct suggested a reaction network that involved both indirect autocatalysis and indirect mutual inhibition between the enantiomers of the reaction product.
机译：借助于内标，通过手性HPLC监测在名义上不存在任何对映选择性催化剂的情况下在丙酮和4-硝基苯甲醛之间进行的醛醇缩合反应。收集的数据表明，在约50％的实验中，在反应的早期，存在可检测到的初始对映体过量的醛醇产物。 24小时后，只有一小部分反应含有非外消旋的羟醛产物。自然光活动的这种暂时出现可能是耦合反应网络的特征，该反应网络导致了自发的镜像对称破坏过程，该过程起源于非常低的转化率（即，强烈依赖于第一阶段发生的事件）。处理）。该反应在醛醇产物中不是自催化的，这排除了简单的弗兰克型反应网络作为观察到的对称破坏的来源。另一方面，双羟醛加合物的分离和表征表明反应网络涉及反应产物的对映异构体之间的间接自身催化和间接相互抑制。

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