Integration of phase transfer catalysis into aqueous transfer hydrogenation

The Golden Age of Transfer Hydrogenation

“…Subsequently some water-soluble polymer-supported, ,, chitosan-anchored or surface-active , ruthenium catalysts have been used in TH reactions. Surfactants are useful to significantly improve the catalytic performances of water-soluble ruthenium catalysts. − A water-soluble anionic ligand derived from DPEN (DPEN = 1,2-diphenylethylenediamine) skeleton bearing two hydrophilic anionic sulfate groups was readily prepared and used to mediate ATH of ketones in aqueous formate in the presence of the ruthenium precursor [RuCl 2 ( p -cymene)] 2 . Considerable enhancement of activity was observed upon using a cationic surfactant such as CTAB (cetyltrimethylammonium bromide) or CPB (cetylpyridine bromide), presumably caused by accelerated transformation of formate ions from aqueous solution to micellar phases (Scheme ).…”

Transfer hydrogenative reductive amination of aldehydes in aqueous sodium formate solution

“…Other examples of catalytic transfer hydrogenation of ketones in aqueous mixed media have also been reported. [20][21][22][23][24][25] However, there is little information on transfer hydrogenative aqueous reductive amination in the literature. [26][27][28][29] This paper reports a practical and efficient catalytic transfer hydrogenative reductive amination of aldehydes using the Noyori-Ikariya precatalyst RuCl(TsDPEN) (p-cymene) (1) in aqueous sodium formate solution.…”

Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones

“…Due to its large abundance and lower toxicity, iron serves as a greener alternative to ruthenium, rhodium, and iridium, metals that are typically used in such a process. 4c, 6,8,9 Results and discussion…”