Versatile (Pentamethylcyclopentadienyl)rhodium-2,2′-Bipyridine (Cp*Rh-bpy) Catalyst for Transfer Hydrogenation of N-Heterocycles in Water was written by Zhang, Lingjuan;Qiu, Ruiying;Xue, Xiao;Pan, Yixiao;Xu, Conghui;Li, Huanrong;Xu, Lijin. And the article was included in Advanced Synthesis & Catalysis in 2015.Reference of 5448-43-1 This article mentions the following:
A study employing the catalytic system consisting of (pentamethylcyclopentadienyl)rhodium dichloride dimer [Cp*RhCl2]2 and 2,2′-bipyridine (bpy) for transfer hydrogenation of a variety of quinoxalines, quinoxalinones, quinolines and indoles under aqueous conditions with formate as the hydrogen source is reported. This approach provides various tetrahydroquinoxalines, dihydroquinoxalinones, tetrahydroquinolines and indolines in good to excellent yields. The activity of the catalyst towards quinoxalines and quinoxalinones is excellent, with a substrate to catalyst ratio (S/C) of 10000 being feasible. The choice of ligand is critical to the catalysis, and the aqueous phase reduction is highly pH-dependent, with acidic pH values needed for optimal reduction The catalyst is easy to access, and the reaction is operationally simple without requiring an inert atm. In the experiment, the researchers used many compounds, for example, 6-Chloroquinoxaline (cas: 5448-43-1Reference of 5448-43-1).
6-Chloroquinoxaline (cas: 5448-43-1) belongs to quinoxaline derivatives. Condensed heterocycles of quinoxalines have become attractive targets in synthetic and medicinal chemistry due to their significant biological activities. The parent substance of the group, quinoxaline, results when glyoxal is condensed with 1,2-diaminobenzene. Substituted derivatives arise when α-ketonic acids, α-chlorketones, α-aldehyde alcohols and α-ketone alcohols are used in place of diketones.Reference of 5448-43-1
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider