Double SO₂ Insertion into 1,7-Diynes Leading to Functionalized Naphtho[1,2-c]thiophene 2,2-dioxides

Ai-Fang Wang, Wen-Juan Hao,* Yi-Long Zhu, Guigen Li, Peng Zhou, Shu-Jiang Tu,* Bo Jiang*

A novel metal-free double SO₂ insertion/multicomponent bicyclization cascades of benzene-linked 1,7-diynes has been estab-lished by treatment with aryldiazonium tetrafluoroborates and DABCO-bis(sulfur dioxide) under redox-neutral conditions, providing a range of dual sulfone-containing naphtho[1,2-c]thiophene 2,2-dioxides with generally high stereoselectivity. The reaction pathway is proposed to proceed through the sequence of arylsulfonyl radical-induced 6-exo-dig/5-endo-trig bicyclization, H-abstraction and diazotization.

ACS Omega 2018, 3, 1482–1491