Eosin‐Y‐Catalyzed Photoredox C−S Bond Formation: Easy Access to Thioethers

Abstract

An operationally simple Eosin Yc atalyzed sulfenylation of hydrazones has been realized to afford ar ange of thioethers under visible light. The methodology provides high yields of thioethers under ambient conditions employ-ing readily availablea nd inexpensive startingm aterials. The reactionh as broad substrate scopea nd is compatible with variousfunctional groups.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Visible‐Light Photoredox Catalyzed C−N Coupling of Quinoxaline‐2(1H)‐ones with Azoles without External Photosensitizer

“…Subsequently, several photocatalysts, including Ru(bpy) 2 Cl 2 , methylene blue, fluorescein, rose bengal and eosin Y, were examined to improve the efficiency of the [c] 390-395 nm CH 3 CN -82 26 [d] 390-395 nm CH 3 CN -Trace 27 [e] 390-395 nm CH 3 CN -71 28 [f] 390-395 nm CH 3 CN -84 29 [g] 390-395 nm CH 3 CN -73 30 [h] 390 Cl 2 ) = 0.77 V versus SCE in acetonitrile, [26] E p/2 (methylene blue) = 1.60 V versus SCE in acetonitrile, [27] E p/2 (fluorescein) = 0.78 V versus SCE in acetonitrile, [28] E p/2 (rose bengal) = 0.99 V versus SCE in acetonitrile, [29] E p/2 (eosin Y) = 0.79 V versus SCE in acetonitrile]. [30] So, the above mentioned photocatalysts cannot react with substrate 1 a (E p/2 = 1.84 V versus SCE in acetonitrile) or 2 a (E p/2 = 1.81 V versus SCE in acetonitrile) via an electron transfer process. In addition, the maximum absorption wavelength of photosensitizer Ru(bpy) 2 Cl 2 , methylene blue, fluorescein, rose bengal and eosin Y is located around 450 nm, 520 nm and 530 nm, respectively, and substrate 1 has a little absorbance to light in the range of 450-530 nm ( Figure S5 of ESI for detail).…”

“…Subsequently, several photocatalysts, including Ru(bpy) 2 Cl 2 , methylene blue, fluorescein, rose bengal and eosin Y, were examined to improve the efficiency of the reaction, but failed (Table , entries 18–22). Ru(bpy) 2 Cl 2 , methylene blue, fluorescein, rose bengal and eosin Y exhibited no any reactivity to the reaction owing to their lower oxidation potentials [ E p/2 (Ru(bpy) 2 Cl 2 )=0.77 V versus SCE in acetonitrile, E p/2 (methylene blue)=1.60 V versus SCE in acetonitrile, E p/2 (fluorescein)=0.78 V versus SCE in acetonitrile, E p/2 (rose bengal)=0.99 V versus SCE in acetonitrile, E p/2 (eosin Y)=0.79 V versus SCE in acetonitrile] . So, the above mentioned photocatalysts cannot react with substrate 1 a ( E p/2 =1.84 V versus SCE in acetonitrile) or 2 a ( E p/2 =1.81 V versus SCE in acetonitrile) via an electron transfer process.…”

Eosin: a versatile organic dye whose synthetic uses keep expanding

“…In 2019, the group of Singh published a new methodology for the synthesis of aromatic thioethers 127 from hydrazones 125 (Scheme 32). 50 The authors propose that the transformation begins when excited state eosin accepts an electron (*EY → EY •− ) from the thiol substrate 126. Following loss of a proton, the RS • radical is formed.…”

Ultrahigh sun‐light‐responsive/not responsive integrated catalyst for C‐S arylation/humidity sensing

“…[38] Many researchers are used transition-metal as a catalyst for direct C-S arylation but they still suffer from many drawbacks such as high cost, poor stability, and band gap problems etc. [39][40][41] To minimize these drawbacks, sun-light-responsive, metal-free, highly efficient and selective TBPCOF-fACC photocatalyst for direct C-S arylation was synthesized. The visible light mediated direct C-S arylation proceeds via radical Markovnikov addition pathway.…”