Easily available α-carbonyl acetates serve as convenient alkyl radical source for an efficient, photocatalytic cross-coupling with a great variety of styrenes. Activation of electronically different α-acetylated acetophenone derivatives could be effected via LUMO lowering catalysis using a superior, synergistic combination of water and (water-compatible) Lewis acids. Deliberate application of fac-Ir(ppy)₃ as photocatalyst to enforce an oxidative quenching cycle is crucial to the success of this (umpolung type) transformation. Mechanistic particulars of this dual catalytic coupling reaction have been studied in detail using both Stern–Volmer and cyclic voltammetry experiments. As demonstrated in more than 30 examples, our water-assisted LA/photoredox catalytic activation strategy allows for excess-free, equimolar radical cross-coupling and subsequent formal Markovnikov hydroxylation to versatile 1,4-difunctionalized products in good to excellent yields.

中文翻译：

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一种协同 LUMO 降低策略，在水中使用路易斯酸催化，实现苯乙烯的光氧化还原催化、官能化 C-C 交叉偶联†

容易获得的 α-羰基乙酸酯可作为方便的烷基自由基源，与多种苯乙烯进行有效的光催化交叉偶联。电子不同的 α-乙酰化苯乙酮衍生物的活化可以通过使用水和（与水相容的）路易斯酸的优异协同组合的 LUMO 降低催化来实现。有意应用fac -Ir(ppy) ₃作为光催化剂来加强氧化猝灭循环对于这种（umpolung 型）转化的成功至关重要。使用 Stern-Volmer 和循环伏安法实验详细研究了这种双催化偶联反应的机理细节。正如 30 多个例子所证明的，我们的水辅助 LA/光氧化还原催化活化策略允许过量游离、等摩尔自由基交叉偶联和随后的正式马尔可夫尼科夫羟基化，以良好到优异的产率生成多功能 1,4-双官能化产物。