Cu2 O Nanocrystals-Catalyzed Photoredox Sonogashira Coupling of Terminal Alkynes and Arylhalides Enhanced by CO2.

Herein the first visible-light-activated Sonogashira C-C coupling reaction at room temperature catalyzed by single-metal heterogeneous Cu2 O truncated nanocubes (Cu2 O TNCs) was developed. A wide variety of aryl halides and terminal alkynes worked well in this recyclable heterogeneous photochemical process to form the corresponding Sonogashira C-C coupling products in good yields. Mechanistic control studies indicated that CO2 enhances the formation of light-absorbing heterogeneous surface-bound CuI -phenylacetylide (λmax =472 nm), which further undergoes single-electron transfer with aryl iodides/bromides to enable Sonogashira C sp 2 -Csp bond formation. In contrast to literature-reported bimetallic TiO2 -containing nanoparticles as photocatalyst, this work avoided the need of cocatalysis by TiO2 . Single-metal CuI in Cu2 O TNCs was solely responsible for the observed C sp 2 -Csp coupling reactions under CO2 atmosphere.