The Cover Feature shows the Lewis base‐catalyzed activation of alcohols for nucleophilic substitutions (S_N) using phenyl chloroformate (PCF) as inherently safe phosgene substitute. In their Full Paper, B. Zoller et al. explain that S_N‐reactions are typically facilitated by stoichiometric reagents, which effect an enhanced thermodynamic driving force and favourable kinetics. In fact, phosgene (COCl₂) is the least expensive reagent for initiation of S_N‐type transformations. However, it is also a highly toxic gas, which was used as warfare agent. We discovered that phosgene can be replaced by much less hazardous PCF in C−Cl and C−Br bond formations, if a suitable Lewis base catalyst is involved. In addition, the use of PCF also resulted in improved yields, as shown by a rigorous comparison. Importantly, the reaction by‐product phenol can be recycled in an industrial setting using cost‐efficient phosgene. More information can be found in the Full Paper by B. Zoller et al.

中文翻译：

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封面人物：Lewis碱催化通过氯甲酸酯类作为光气代用品来活化酒精（ChemCatChem 22/2020）

封面功能显示了使用氯甲酸苯酯（PCF）作为内在安全的光气替代物，亲核取代（S _N）的Lewis碱催化的醇活化。B. Zoller等人在其论文全文中。解释说，化学计量试剂通常会促进S _N反应，从而提高热力学驱动力和动力学。实际上，光气（COCl ₂）是引发S _N的最便宜的试剂类型转换。但是，它还是一种剧毒气体，被用作战剂。我们发现，如果涉及合适的路易斯碱催化剂，则光气可以用危害性较小的PCF取代，CPC和C-Br键的形成。此外，严格的比较显示，使用PCF还可以提高产量。重要的是，反应副产物苯酚可以使用经济高效的光气在工业环境中回收。可以在B. Zoller等人的论文全文中找到更多信息。