Multicomponent Annulative SO₂ Insertion of Heteroatom‐Linked 1,7‐Diynes for Accessing Tricyclic Sulfones

Abstract

A metal‐free radical multicomponent bicyclization of heteroatom‐linked 1,7‐diynes with aryl diazonium tetrafluoroborates and DABCO‐bis(sulfurdioxide) (DABSO) is reported, enabling annulative SO2 insertion access to produce two types of skeletally diverse tricyclic sulfones, namely, thieno[3,4‐c]quinoline 2,2‐dioxides and thieno[3,4‐c]chromene 2,2‐dioxides, with moderate to good yields by simply tuning the linkers of the 1,7‐diynes. This protocol demonstrates remarkable compatibility regarding N‐ and O‐linked 1,7‐diynes with different substitution patterns and aryl diazonium tetrafluoroborates.

Recent Advancements in Metal‐Catalyst‐Free Multicomponent Radical Sulfonylation of Alkynes

“…(Scheme 5). [14] The strategy allows for the production of two cyclic sulfones with different backbones under mild conditions, simply by varying the linkers of the 1,7diynes. Supported by control experiments and literature survey, the proposed mechanism involves an initial SET between the aryldiazonium cation and DABSO generating aryl radicals, SO 2 , and a radical cation intermediate E. Subsequently, the aryl radical reacts with SO 2 to form an aryl sulfonyl radical, which then regioselective adds to the terminal alkyne of 1,7-diyne yielding an alkenyl radical.…”

Photocatalytic Multicomponent Annulation of Amide-Anchored 1,7-Diynes Enabled by Deconstruction of Bromotrichloromethane

“…This type of reaction provides a unique and direct way to construct intricate architectures that cannot be obtained by thermal processes [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. In particular, photocatalytic annulation cascade reactions of 1, n -diynes appear as a remarkable and applicable platform for facilitating the formation of poly-substituted isocyclic and heterocyclic compounds via synergistic interactions across their two unsaturated carbon–carbon triple bond [ 36 , 37 , 38 ]. Furthermore, Kharasch-type addition/cyclization of unsaturated systems by taking advantage of photocatalytic strategy is a convenient and atom economy method for producing polyhalogenated products [ 39 , 40 , 41 , 42 , 43 ].…”