42917-47-5Relevant articles and documents
Paired Electrolysis Enabled Ni-Catalyzed Unconventional Cascade Reductive Thiolation Using Sulfinates
Kang, Jun-Chen,Li, Zi-Hao,Chen, Chao,Dong, Li-Kun,Zhang, Shu-Yu
supporting information, p. 15326 - 15334 (2021/10/25)
Herein, we have reported a nickel-catalyzed cascade reductive thiolation of aryl halides with sulfinates driven by paired electrolysis. This protocol uses sulfinates as the sulfur source, and various thioethers could be synthesized under mild conditions. By mechanism exploration, we find that a cascade chemical step is allowed on the electrode interface and could alter the reaction pathway in paired electrolysis, whose findings could help the discovery of novel cascade reactions with unique reactivity.
Photoredox Nickel-Catalyzed C-S Cross-Coupling: Mechanism, Kinetics, and Generalization
Qin, Yangzhong,Sun, Rui,Gianoulis, Nikolas P.,Nocera, Daniel G.
supporting information, p. 2005 - 2015 (2021/02/06)
Photoredox-mediated nickel-catalyzed cross-couplings have evolved as a new effective strategy to forge carbon-heteroatom bonds that are difficult to access with traditional methods. Experimental mechanistic studies are challenging because these reactions involve multiple highly reactive intermediates and perplexing reaction pathways, engendering competing, but unverified, proposals for substrate conversions. Here, we report a comprehensive mechanistic study of photoredox nickel-catalyzed C-S cross-coupling based on time-resolved transient absorption spectroscopy, Stern-Volmer quenching, and quantum yield measurements. We have (i) discovered a self-sustained productive Ni(I/III) cycle leading to a quantum yield φ > 1; (ii) found that pyridinium iodide, formed in situ, serves as the dominant quencher for the excited state photocatalyst and a critical redox mediator to facilitate the formation of the active Ni(I) catalyst; and (iii) observed critical intermediates and determined the rate constants associated with their reactivity. Not only do the findings reveal a complete reaction cycle for C-S cross-coupling, but the mechanistic insights have also allowed for the reaction efficiency to be optimized and the substrate scope to be expanded from aryl iodides to include aryl bromides, thus broadening the applicability of photoredox C-S cross-coupling chemistry.
Concerted aryl-sulfur reductive elimination from PNP pincer-supported Co(iii) and subsequent Co(i)/Co(iii) comproportionation
Foley, Bryan J.,Palit, Chandra Mouli,Bhuvanesh, Nattamai,Zhou, Jia,Ozerov, Oleg V.
, p. 6075 - 6084 (2020/07/10)
This report discloses a combined experimental and computational study aimed at understanding C-S reductive elimination from Co(iii) supported by a diarylamido/bis(phosphine) PNP pincer ligand. Divalent (PNP)Co-aryl complexes could be easily oxidized to five-coordinate Co(iii) derivatives, and anion metathesis provided five-coordinate (PNP)Co(Ar)(SAr′) complexes of Co(iii). In contrast to their previously described (POCOP)Co(Ar)(SAr′) analogs, but similarly to the (PNP)Rh(Ar)(SAr′) and (POCOP)Rh(Ar)(SAr′) analogs, (PNP)Co(Ar)(SAr′) undergo C-S reductive elimination with the formation of the desired diarylsulfide product ArSAr′. DFT studies and experimental observations are consistent with a concerted process. However, in contrast to the Rh analogs, the immediate product of such reductive elimination, the unobserved Co(i) complex (PNP)Co, un-dergoes rapid comproportionation with the (PNP)Co(Ar)(SAr′) starting material to give Co(ii) compounds (PNP)Co-Ar and (PNP)Co-SAr′.
