<p>Allylic ethers are important functional motifs widespread in bioactive molecules and natural products and serve as versatile synthetic intermediates for value-added target molecules. Therefore, developing general and direct methods to allylic ethers from feedstocks is highly desirable. Direct cross-coupling of alkenes with free alcohols by allylic C-H functionalization under mild conditions represents the most ideal way for the synthesis of branched allylic ethers. Moreover, branch-selective allylic C-H oxygenation imposes additional challenge due to the increased steric hindrance. Herein, a dual catalysis of visible-light and cobaloxime enables allylic C-H direct oxygenation of styrenes with alcohols to afford branched allylic ethers has been developed. Notably, exclusive regio- and chemoselective mono-etherification of C-H bond to give branched allylic ethers with primary, secondary, and tertiary free alcohols. Moreover, other oxygen-based nucleophiles, such as carboxylate and cyclic 1,3- diketones, are also compatible in the reaction, providing a mild and robust allylic oxygenation of more steric hindered C-H from easily available alkenes.</p>

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Dual-catalyzed branch-selective allylic C–H oxygenation of terminal styrenes with free oxygen-based nucleophiles

  • Yu-Feng Ren,
  • Jin-Kui Chen,
  • Qiong Yu,
  • Wei Shu

摘要

Allylic ethers are important functional motifs widespread in bioactive molecules and natural products and serve as versatile synthetic intermediates for value-added target molecules. Therefore, developing general and direct methods to allylic ethers from feedstocks is highly desirable. Direct cross-coupling of alkenes with free alcohols by allylic C-H functionalization under mild conditions represents the most ideal way for the synthesis of branched allylic ethers. Moreover, branch-selective allylic C-H oxygenation imposes additional challenge due to the increased steric hindrance. Herein, a dual catalysis of visible-light and cobaloxime enables allylic C-H direct oxygenation of styrenes with alcohols to afford branched allylic ethers has been developed. Notably, exclusive regio- and chemoselective mono-etherification of C-H bond to give branched allylic ethers with primary, secondary, and tertiary free alcohols. Moreover, other oxygen-based nucleophiles, such as carboxylate and cyclic 1,3- diketones, are also compatible in the reaction, providing a mild and robust allylic oxygenation of more steric hindered C-H from easily available alkenes.