Photoredox‐Catalyzed Functionalization of Alkenes with Thiourea Dioxide: Construction of Alkyl Sulfones or Sulfonamides

Abstract

Summary of main observation and conclusion Sulfonylation of alkenes through photoredox‐catalyzed functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkyl sulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur dioxide radical anion (SO2‐) derived from the oxidation of sulfur dioxide anion (SO22–) is proposed, which is supported by fluorescence quenching experiments.

Recent Progress and Emerging Technologies towards a Sustainable Synthesis of Sulfones

“…[102] While proceeding through a different mechanistic pathway, the photoredox‐catalyzed functionalization of alkenes with thiourea dioxide gives access to the same type of alkyl sulfone products (Scheme 56 , method C). [102c] …”

Visible Light as the Key for the Formation of Carbon–Sulfur Bonds in Sulfones, Thioethers, and Sulfonamides: An Update

“…The reaction was performed under visible light and using Ir(ppy) 3 as the photocatalyst. 56 The sulfonylation of electron-poor heterocycles and alkenes to access sulfones 103 57 and 105 58 and sulfonamides was realized by applying another SO 2 surrogate, thiourea dioxide, which can release sulfur dioxide anions upon treatment with a base (Scheme 38). Under visible light, the interaction between the released SO 2 2with the heteroaryl halides or alkenes generates a sulfinate intermediate which can be trapped by the electrophile.…”

“…(PDI) as the photocatalyst; no product was obtained using other commonly used photosensitizers (Scheme 38B). 58 The reaction of O-acyl oximes 106 with alkenes 107, K 2 S 2 O 5 (as a SO 2 source), and nucleophiles was achieved by blue LED light photocatalysis using Ir(ppy) 3 to give -cyano sulfones 108 (Scheme 39). 59 O-Acyl oximes 106 undergo C-C bond cleavage to give an iminyl radical, which traps the sulfur radical generated from K 2 S 2 O 5 , thus starting a tandem reaction in which terminal alkenes 107 are involved.…”

Generation of Sulfonylated Tetrazoles through an Iron-Catalyzed Multicomponent Reaction Involving Sulfur Dioxide

“…Sulfones are subjects of great interest in the area of pharmaceuticals and agrochemicals ( Drews, 2000 ; Feng et al., 2016 ; Patai et al, 1988 ). In recent years, sulfonylation reaction via a radical process with sulfur dioxide surrogates, DABCO·(SO 2 ) 2 and inorganic sulfites, has proven to be a promising approach for the synthesis of diverse sulfone-containing molecules ( Bisseret and Blanchard, 2013 ; Chen et al., 2020 ; Deeming et al., 2014 ; Emmett and Willis, 2015 ; Gong et al., 2020 ; He et al., 2020 ; Li et al., 2020a , 2020b ; Liu et al., 2020 ; Meng et al., 2020 ; Nair et al., 2020 ; Qiu et al., 2018a , 2018b ; Wang et al., 2019 ; Ye et al., 2019 , 2020a , 2020b , 2020c ; Zheng and Wu, 2017 ; Zhou et al., 2020 ). Recently, our group described a copper-catalyzed four-component reaction of terminal alkynes, aryldiazonium tetrafluoroborates, DABCO·(SO 2 ) 2 , and potassium halide, giving rising to a range of β-halo alkenylsulfones ( Xiang et al., 2017 ).…”