Photocatalytic Biheterocyclization of 1,7-Diynes for Accessing Skeletally Diverse Tricyclic 2-Pyranones

Lu Wang,^# Ting Xu,^# Qian Rao, Tian-Shu Zhang,* Wen-Juan Hao,* Shu-Jiang Tu, Bo Jiang*

A new and green route to skeletally diverse oxo-heterocyclic architectures such as pyrano[3,4-c]chromen-2-ones and pyrano[3,4-c]quinolin-2-ones is reported via an unprecedented photocatalytic Kharasch-type cyclization/1,5-(S_N″)-substitution /elimination/6π-electrocyclization /double nucleophilic substitution cascade starting from easily available heteroatom-linked 1,7-diynes and low-cost CBrCl₃. During this reaction process, the full scission of carbon-halogen bonds of BrCCl₃ was realized to directly build up two new rings, including a lactone scaffold, with utilization of H₂O as the oxygen source of ester group.

Org. Lett. 2021, 23, 7845-7850; DOI: 10.1021/acs.orglett.1c02865