Visible Light‐Driven, Photocatalyst‐Free Arbuzov‐Like Reaction via Arylazo Sulfones

Abstract

A visible light‐induced formation of Aryl‐Phosphorous bonds starting from arylazo sulfones and triaryl (or trialkyl)phosphites in the absence of any photoredox catalyst and any additives was developed. This reaction showed a broad substrate scope and afforded (hetero)aryl phosphonates in good yields and in up to the gram scale.magnified image

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.…”

“…Preparation of arylazo sulfones 1u, 1s, 1w, 1ah: [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.…”

“…[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!

“…Thus, allylarenes (by reaction with allyl sulfone moieties), [110] heterobiaryls (via Ar-H activation of a suitable heteroarene) [111] and triarylethylenes (TAEs) (by using 1,1-diarylethylenes as the coupling partner) [112] have been smoothly achieved by having recourse to arylazo sulfones chemistry. 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.…”