Asymmetric transfer hydrogenation of ketones in aqueous solution catalyzed by rhodium(III) complexes with C2-symmetric fluorene-ligands containing chiral (1R,2R)-cyclohexane-1,2-diamine

Abstract

Dois ligantes C 2 -simétricos bis(sulfonamide) contendo o fluoreno-quiral (1R,2R)-ciclohexano-1,2-diamina foram complexados com Rh III (Cp*) e usados como catalizador para redução aromática de cetonas. Os alcoois secundários correspondentes foram obtidos com ee 87-100% e rendimento de 85-99%, sob condições de transferência de hidrogenio assimétrica (THA), usando formato de sodio aquoso como fonte de hidretos. Usando acetofenona, obteve-se ee de 94% e rendimento de 86-97%, com uma razão substrato/catalizador de 10.000.Two C 2 -symmetric bis(sulfonamide) ligands containing fluorene-chiral (1R,2R)-cyclohexane-1,2-diamine were complexed to Rh III (Cp*) and used as catalyst to reduce aromatic ketones. The corresponding chiral secondary alcohols were obtained in 87-100% ee and 85-99% yield, under asymmetric transfer hydrogenation (ATH) conditions using aqueous sodium formate as the hydride source. With acetophenone, 94% ee and 86-97% yield was achieved with substrate/catalyst (S/C) ratio of 10,000.

Catalytic asymmetric transfer hydrogenation of ketones: recent advances

“…To the best of our knowledge, only one amino alcohol, the ligand 6 ( 54 with different activity for the ATH of phenones (Table 3). Table 3.…”

Product Selectivity in Homogeneous Artificial Photosynthesis Using [(bpy)Rh(Cp*)X]n+-Based Catalysts

“…However, only turnover numbers (TONs) below 10 were found for the Rh catalyst and the Ru chromophore. [33][34][35][36][37][38], reaction (b) [39,40], reaction (c) [26,29,[41][42][43][44], reaction (d) [45][46][47][48][49][50][51][52][53][54][55], and reaction (e) [48,[56][57][58][59].…”

“…Within several thermal processes, the use of chiral N,N-chelating ligands coordinated to the Rh(Cp*) moiety allowed ketone reductions with high enantioselectivity, indicating that the ligand-induced asymmetry of the whole catalyst is sufficiently preserved at the rhodium center to sterically discriminate between the two different enantiotopic faces of the ketone [42][43][44]. In addition, chromenones, a group of cyclic α,β-unsaturated ketones, were reduced to the fully saturated chiral alcohol with high ee-values, using HCOONa as a hydride donor [29].…”

“…. Range of carbonyl compounds that were reduced stereoselectively to the corresponding alcohols using enantiopure [(NN)Rh(Cp*)X] n+ catalysts and sodium formate as a hydride source [29,[42][43][44].…”

Preparation of Symmetrical and Nonsymmetrical Fluorene ­Sulfonamide Scaffolds

“…1 For example, C2 symmetric bis-sulfonamide 2 is an effective ligand in the rhodium catalysed asymmetric transfer hydrogenation of ketones. 2 Bis-sulfonamides are also prevalent in many commercial screening libraries and have been identified as hit compounds on diverse protein targets including alanine racemase, 3 cysteine protease, 4 and 17-HSD1. 5 In addition, bissulfonamide 3 has been used in chemical biology as a novel DNA G quadruplex ligand showing further applications for this class of compound.…”