Modification of [2.2]Paracyclophanes via Cobalt/Salox‐Catalyzed Enantioselective Electrooxidative or Photoredox C─H Acyloxylation and Alkoxylation
Fan‐Rui Huang, Ming‐Ya Teng, Hui Qiu, Qi‐Jun Yao, Bing‐Feng Shi
Abstract
Chiral [2.2]paracyclophanes (PCPs) have widespread application in asymmetric catalysis and materials science. However, enantioselective C─H activation of PCPs remains elusive and challenging due to steric hindrance, which differs significantly from conventional aryl C─H bonds. Herein, we present a cobalt/Salox-catalyzed enantioselective dehydrogenative C─H acyloxylation and alkoxylation of racemic PCPs with carboxylic acids and alcohols under electrooxidative or photoredox conditions. This innovative approach leverages traceless electrons or oxygen to replace traditional stoichiometric metal oxidants, allowing the reaction to proceed under mild conditions. The method enables the efficient synthesis of oxygenated optically enriched PCPs, achieving yields of up to 50% with 99% ee, as well as up to 49% yields and 99% ee for the recovered starting materials, resulting in exceptional s-factors of up to 1057. The reaction exhibits a broad scope, accommodating a diverse array of carboxylic acids, including complicated natural products and pharmaceutical molecules. This strategy not only provides an efficient route for synthesizing optically enriched PCP compounds but also highlights the potential of electrooxidative and photoredox methodologies in asymmetric C─H activation reactions.