Dual rhodium/copper catalysis: Synthesis of benzo[b]fluorenes and 2-naphthalenylmethanones via de-diazotized cycloadditions

Ya-Nan Wu, Ting Xu, Rong Fu, Nan-Nan Wang, Wen-Juan Hao, Shu-Liang Wang,* Guigen Li, Shu-Jiang Tu,*  and Bo Jiang*

A novel synergistic rhodium/copper catalysis has been established, enabling de-diazotized cycloadditions of 1,5-enynes and α-diazocarbonyls toward the selective formation of densely functionalized benzo[b]fluorenes and 2-naphthalenylmethanones. α-Aryldiazoesters results in the formation triple C–C bonds through bimetallic catalysis whereas a range of functionalized naphthalenes with a 1,5-dicarbonyl unit were accomplished using α-diazocarbonyls without substituent at α-position, indicating that substituents at α-position of α-diazocarbonyl unit could control the selectivity of the reaction.

Chem. Commun. 2016, 52, 11943-11946