Visible-Light-Driven Synthesis of Arylstannanes from Arylazo Sulfones

Abstract

The visible-light-driven preparation of (hetero)­aryl stannanes was carried out under both photocatalyst- and metal-free conditions via irradiation of arylazo sulfones in the presence of hexaalkyldistannanes. The reaction shows a high efficiency and a wide substrates scope. The resulting crude organotin derivatives can be directly employed in a Stille protocol.

Metal‐Free Synthesis of Unsymmetrical Aryl Selenides and Tellurides via Visible Light‐Driven Activation of Arylazo Sulfones

“…For chromatography, 200-300 mesh silica gel (Qingdao, China) was employed. 1 H, 13 Preparation of arylazo sulfones 1a-1c, 1e, 1g-1k, 1y, 1aa-1ac, 1ae, 1ag: [47][48][49] a) In a 50 mL round-bottom flask, the chosen aromatic amine (10 mmol) was dissolved in a mixture of H 2 O (5 mL) and HBF 4 (48 % aq , 4 mL). After cooling the reaction mixture to 0°C, sodium nitrite (760 mg in 4 mL of water) was added dropwise in 5 min.…”

“…The resulting mixture was then filtered, and the filtrate was concentrated to give a crude product that was thus purified by dissolution in CH 2 Cl 2 and precipitation by adding cold petroleum ether. 1d-1f, 1l-1r, 1t, 1v, 1x, 1z, 1ad, 1af: [47,48] In a 50 mL round-bottom flask, the suspension of the prepared arenediazonium tetrafluoroborate (10 mmol) in CH 2 Cl 2 (10 mL) was stirred at 0°C, then sodium methanesulfinate (1.12 g, 1.1 equiv.) was added to the reaction mixture in one portion.…”

“…Yellow solid, 1 1-(3,4-Dichlorophenyl)-2-(methylsulfonyl)diazene (1i). [47] Yield: 89 %. Yellow solid, 1 1-(2-Methoxy-4-nitrophenyl)-2-(methylsulfonyl)diazene (1j).…”

“…[46] Such bench-stable derivatives of diazonium salts bear a dyedauxiliary moiety (the -N 2 SO 2 CH 3 group) that imparts both color and reactivity to the molecule allowing for the release of an aryl radical upon visible light irradiation. [46] Such behavior was exploited in the development of several metal-free arylation protocols for the preparation, among the others, of aromatic stannanes, [47] phosphonates, [48] boranes, [49,50] sulfides [50] and arylated heterocycles. [51,52] We thus considered the opportunity of developing a visible light-driven procedure for the synthesis of aryl selenides and tellurides where neither catalyst nor additives were adopted (Scheme 1d).…”

Leaving Groups in Metal‐Free Arylations: Make Your Choice!

“…Analogously, the use of arylazo sulfones in C-Heteroatom bond formation has been the subject of different research groups, for the synthesis of arylboranes, [113] sulfides, [114] sulfoxides [115] (Scheme 24a), arylphosphite [116] and arylstannanes (Scheme 24b). [117] Scheme 23. Wavelenght selective photoreactivity of arylazo sulfones.…”