Visible-light photocatalytic bicyclization of β-alkynyl propenones for accessing diastereoenriched syn-fluoren-9-ones

Zheng-Jia Shen, Hao-Nan Shi, Wen-Juan Hao,* Shu-Jiang Tu,* Bo Jiang*

A novel visible-light photocatalytic bicyclization of β-alkynyl propenones with α-bromocarbonyls for highly diastereoselective synthesis of richly decorated syn-fluoren-9-ones is described. The reaction proceeds via radical-triggered 5-exo-dig cyclization/1,6-H-abstraction/6-endo-trig cyclization cascade and offers a new and practical method for the assembly of 6/5/6 carbocyclic skeleton via C(sp³)-H alkenylation.

Chem. Commun. 2018, 54, 11542-11545