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

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/6 pi-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 two new rings, including a lactone scaffold, using H2O as the oxygen source of the ester group.

Automated summary

A novel and green synthetic route was reported for the construction of diverse oxo-heterocyclic architectures, including pyrano[3,4-c]chromen-2-ones and pyrano[3,4-c]quinolin-2-ones, via an unprecedented photocatalytic reaction cascade starting from readily available heteroatom-linked 1,7-diynes and low-cost CBrCl3. This process involves the cleavage of carbon-halogen bonds of BrCCl3 to form new rings, including a lactone scaffold, with H2O as the oxygen source for the ester group.