Palladium-Catalyzed Anti-Markovnikov Oxidation of Aromatic and Aliphatic Alkenes to Terminal Acetals and Aldehydes

Catalytic anti-Markovnikov (AM) oxidation of terminal alkenes can provide terminally oxyfunctionalized organic compounds. This short review mainly summarizes our recent progress on the Pd-catalyzed AM oxidations of aromatic and aliphatic terminal alkenes to give terminal acetals (oxidative acetalization) and aldehydes (Wacker-type oxidation), along with related reports. These reactions demonstrate the efficacy of the PdCl2 (MeCN)(2)/CuCl/electron-deficient cyclic alkenes/O(2)catalytic system. Notably, electron-deficient cyclic alkenes such as p-benzoquinones (BQs) and maleimides are key additives that facilitate nucleophilic attack of oxygen nucleophiles on coordinated terminal alkenes and enhance the AM selectivity. BQs also function to oxidize Pd(0) depending on the reaction conditions. Several other factors that improve the AM selectivity, such as the steric demand of the nucleo-philes, slow substrate addition, and halogen-directing groups, are also discussed. 1 Introduction 2 Anti-Markovnikov Oxidation of Aromatic Alkenes to Terminal Acetals- 3 Anti-Markovnikov Oxidation of Aromatic Alkenes to Aldehydes 4 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals- 5 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Aldehydes 6 Conclusion

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The review summarizes recent progress in Pd-catalyzed anti-Markovnikov oxidation of terminal alkenes to provide terminally oxyfunctionalized organic compounds. Key additives like BQs are highlighted for enhancing the nucleophilic attack of oxygen nucleophiles on terminal alkenes. Various factors affecting the selectivity of the reaction, including steric hindrance of nucleophiles and substrate addition rate, are also discussed.