278188-48-0Relevant articles and documents
Ligand-Free Ru-Catalyzed Direct sp3 C-H Alkylation of Fluorene Using Alcohols
Shaikh, Moseen A.,Agalave, Sandip G.,Ubale, Akash S.,Gnanaprakasam, Boopathy
, p. 2277 - 2290 (2020/02/04)
The sp3 C-H alkylation of 9H-fluorene using alcohol and a Ru catalyst via the borrowing hydrogen concept has been described. This reaction was catalyzed by the [Ru(p-cymene)Cl2]2 complex (3 mol %) and exhibited a broad reaction scope with different alcohols, allowing primary and secondary alcohols to be employed as nonhazardous and greener alkylating agents with the formation of environmentally benign water as a byproduct. A variety of 9H-fluorene underwent selective and exclusive mono-C9-alkylation with primary alcohols in good to excellent isolated yield (26 examples, 50-92% yield), whereas this reaction with secondary alcohols in the absence of any external oxidants furnished the tetrasubstituted alkene as the major product. Furthermore, a base-mediated C-H hydroxylation of the synthesized 9H-fluorene derivatives afforded 9H-hydroxy-functionalized quaternary fluorene derivatives in excellent yield.
Highly efficient suzuki-miyaura coupling of heterocyclic substrates through rational reaction design
Fleckenstein, Christoph A.,Plenio, Herbert
scheme or table, p. 4267 - 4279 (2009/05/07)
A dicyclohexyl(2-sulfo-9-(3-(4-sulfophenyl)propyl)-9H-fluoren-9-yl) phosphonium salt was synthesized in 64% overall yield in three steps from simple commercially available starting materials. The highly water-soluble catalyst obtained from the corresponding phosphine and [Na2PdCl4] enabled the Suzuki coupling of a broad variety of N- and S-heterocyclic substrates. Chloropyridines (-quinolines) and aryl chlorides were coupled with aryl-, pyridineor indoleboronic acids in quantitative yields in water/n-butanol solvent mixtures in the presence of 0.005-0.05 mol% of Pd catalyst at 100°C, chloropurines were quantitatively Suzuki coupled in the presence of 0.5 mol% of catalyst, and S-heterocyclic aryl chlorides and aryl- or 3-pyridylboronic acids required 0.01-0.05 mol % Pd catalyst for full conversion. The key to the high activity of the Pd-phosphine catalyst is the rational design of the reaction parameters (i.e., the presence of water in the reaction mixture, good solubility of reactants and catalyst in n-butanol/water (3:1), and the electron-rich and sterically demanding nature of the phosphine ligand).
