Cross-Coupling of Meyer-Schuster rearrangement Intermediates under Dual Gold & Photoredox Catalysis

Abstract

Dual gold/photoredox-catalyzed cross-coupling of Meyer-Schuster rearrangement intermediates with arene diazonium salts has been developed, leading to α-arylated enones. Previous C(sp2)-C(sp2) cross-coupling under these dual catalytic system, has been limited to C(sp3)-Au or C(sp2)-Au species that are stable toward proto-demetallation. However, for successful realization of in-situ formed C(sp2)-Au species, oxidative addition must be faster than the proto-demetallation. In this thesis, a general tandem Meyer-Schuster rearrangement/cross-coupling protocol was realized with diazonium salts functioning triple role of reaction partners, oxidants as well as a catalytic activator of propargyl alcohols. Through mechanistic studies, Meyer-Schuster intermediate formed in methanol is most consistent with methyl allenyl ether that are effectively protected from unwanted proto-demetallation. The resulting α-arylated enone compounds serve as precursors of pharmaceutically interesting heterocycles.