79462-49-0Relevant academic research and scientific papers
From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
, p. 6099 - 6104 (2021/08/03)
The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
Dicationic phosphonium salts: Lewis acid initiators for the Mukaiyama-aldol reaction
Barrado, Alejandro G.,Bayne, Julia M.,Johnstone, Timothy C.,Lehmann, Christian W.,Stephan, Douglas W.,Alcarazo, Manuel
, p. 16216 - 16227 (2017/12/06)
Two strategies were used to prepare dicationic phosphonium cations. The first method consists of the reaction of 1-chlorocyclopropenium salts with phosphines to obtain cyclopropenium-substituted phosphonium salts 10a-f[BF4]. Anion exchange was performed to access the corresponding [B(C6F5)4]- analogues 10a-f[B(C6F5)4], which showed much higher solubility in organic solvents. In addition, we developed a synthesis of dicationic phosphonium salts containing 2-, 3-, or 4-methylpyridinium substituents 11a-c[TfO], which were converted as well to their [B(C6F5)4]- analogues 11a-c[B(C6F5)4]. Finally, the phenoxy-substituted phosphonium salt 12[B(C6F5)4] was also prepared. All salts demonstrated remarkable stability in air as compared with their fluorinated analogues. The Lewis acidity of these salts was evaluated by means of theoretical calculations and finally, they were shown to be effective in initiating the Mukaiyama-aldol reaction.
Synthesis of phosphonium salts - Phosphine structure and inorganic salts effects
Meciarov, Maria,Toma, Stefan,Loupy, Andre,Horvath, Branislav
, p. 21 - 33 (2008/12/21)
Solvent-free reactions of 2- and 3-halopyridines with PPh3, PBu3, and PCy3 were studied under conventional heating, as well as under microwave irradiation. No difference was observed in the reaction course between classical and microwave reactions. 2-Bromopyridine gave quantitative yields of 2-pyridyltriphenylphosphonium bromide within few minutes at 190C. Equimolar amounts of some inorganic salts (LiPF6, LiOTf, LiBr, NaPF6, KPF6) were necessary for the reactions of the other 2-halopyridines. 3-Halopyridines did not react with PPh3 even in the presence of LiPF6. Their reactions with PCy3 in the presence of LiPF6 resulted in the quantitative formation of dicyclohexylphosphine oxide.
