Chang Rui, Pang Yubing, Ye Juntao
Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China.
Angew Chem Int Ed Engl. 2023 Nov 6;62(45):e202309897. doi: 10.1002/anie.202309897. Epub 2023 Oct 9.
Herein, we report a photoinduced approach for hydroarylation of unactivated olefins using 4-hydroxycoumarins as the arylating reagent. Key to the success of this reaction is the conversion of nucleophilic 4-hydroxycoumarins into electrophilic carbon radicals via photocatalytic arene oxidation, which not only circumvents the polarity-mismatch issue encountered under ionic conditions but also accommodates a broad substrate scope and inhibits side reactions that were previously observed. Moreover, divergent reactivity was achieved by changing the photocatalyst, enabling a subsequent [2+2] cycloaddition to deliver cyclobutane-fused pentacyclic products that are otherwise challenging to access in high yields and with high diastereoselectivity. Mechanistic studies have elucidated the mechanism of the reactions and the origin of the divergent reactivity.
在此，我们报道了一种以4-羟基香豆素为芳基化试剂，用于未活化烯烃氢芳基化的光诱导方法。该反应成功的关键在于通过光催化芳烃氧化将亲核的4-羟基香豆素转化为亲电碳自由基，这不仅规避了离子条件下遇到的极性不匹配问题，还具有广泛的底物范围，并抑制了先前观察到的副反应。此外，通过改变光催化剂实现了不同的反应活性，使得后续的[2+2]环加成反应能够提供环丁烷稠合的五环产物，否则以高收率和高非对映选择性获得这些产物具有挑战性。机理研究阐明了反应机理和不同反应活性的起源。
