Regioselective synthesis of polycyclic sulfones via radical-induced three-component bicyclization cascades

Xiao-Yan Qin, Long He, Jing Li, Wen-Juan Hao*, Shu-Jiang Tu, Bo Jiang*

New radical-triggered three-component bicyclization cascades of 2-alkynyl aryldiazonium tetrafluoroborates with sulfur dioxide surrogate of DABCO·(SO₂)₂ and internal alkynes such as haloalkynes and ynones have been first reported, leading to 49 examples of polycyclic sulfones with moderate to good yields and high levels of regioselectivity. This transformation initiated by in-situ generated arylsulfonyl radical proceeds efficiently under mild and neutral redox conditions, which provide an easy and metal-free pathway toward a range of richly decorated indeno[1,2-c]thiochromene 5,5-dioxides.

Chem. Commun. 2019, 55, 3227-3230