已经在连续流动条件下以克为单位进行了一组烷基和酰基自由基在贫电子烯烃或偶氮二羧酸二异丙酯上的原子经济自由基共轭加成反应。该方法基于使用无机光催化剂四丁基癸二酸铵(TBADT),它能够选择性地活化不同底物(包括醛,酰胺,醚和烷烃)中的多种CH键。根据该程序已经合成了广泛的合成靶,包括1,4-双官能化的衍生物(例如1,4-二酮或酮酯)。所有反应均在中观条件下进行规模的流量光反应器,包括缠绕在水冷500 W中压汞蒸气灯周围的紫外线透明FEP管(氟化乙烯丙烯)的盘管。这种光化学设备的使用导致了停留时间的减少,相对于相应的批处理过程所测得的停留时间而言,STY(时空产率)和生产率值显着提高,通常会导致整体效率的提高。过程的可持续性(过程质量强度– PMI –值低至10 kg kg -1)。
AbstractThe direct benzylation of electrophilic alkenes with alkylbenzenes has been achieved by decatungstate photocatalysis in a high ionic strength medium (5:1 acetonitrile/water mixed solvents, 0.5 M lithium perchlorate). The reaction has been extended to ring‐substituted (Cl, F, CN) toluenes and further alkylbenzenes. Intramolecular selectivity (p‐cymene, 4‐methylanisole) and deuteration effects support the atom transfer character of the process that, however, requires a sufficient stabilization of the intermediate polar exciplex to occur. The reactivity of the decatungstate anion is compared with that of aromatic ketones, the benchmark of photochemical hydrogen/electron transfer processes.magnified image