Visible Light-Induced Synthesis of Fluorenes from -Biaryldiazoacetates

Carbenes are pivotal reactive intermediates for accessing a wide range of complex molecules, which are frequently used in chemical synthesis and medicinal advancement. We have developed a convenient approach to fluorenes from alpha-biaryldiazoacetates via low-energy blue light-induced photochemical generation of a carbene intermediate, where the reaction took place at room temperature without any catalysts, bases, or oxidants in acetonitrile. The present catalyst-free and operationally simple approach enables highly efficient annulation of alpha-biaryldiazoacetates under mild reaction conditions.