New C2-symmetric bis(sulfonamide)-cyclohexane-1,2-diamine-RhCp∗ complex and its application in the asymmetric transfer hydrogenation (ATH) of ketones in water

Synthesis of C2-symmetric 1,2-diamine-functionalized organocatalysts: mimicking enzymes in enantioselective Michael addition reactions

“…3). 6,8,9 With the new derivatives 1a-c, 2a-b in hand, we began to evaluate their catalytic behavior in the classical Michael reaction between isobutyraldehyde/acetone and nitrostyrene, 10 and the results are displayed in Table 1. As can be seen, the reaction proceeded smoothly at rt in 5 days leading to good yields and enantioselectivities.…”

“…Based on these considerations, we synthesized a series of C 2 -symmetric bis-sulfonamide ligands derived from 1,3-benzene sulfonyl chloride and biphenyl-4,4 0 -disulfonyl chloride and tested them in the asymmetric transfer hydrogenation of aromatic ketones (ATH) with Ru(II) and Rh(III) complexes (enantioselectivities up to 99%, yields up to 99%). 6 Interestingly, the structural features of these C 2 -symmetric bis-sulfonamide ligands are also suitable as organocatalysts for the conjugate Michael addition reaction; with a primary amine group that can activate acetone by formation of an enamine intermediate, and a proton donor from the sulfonamide group (NH-SO 2 Ar) for hydrogen bonding to the nitro group of the alkene. Furthermore, previous literature showed acetate anion recognition by similar bis-1,3-benzenedisulfonamides, where the two acetate oxygens were hydrogen bonded to the NHSO 2 groups.…”

Novel N-coordinate half-sandwich ruthenium(II) arene complexes bearing sulfonamide fragments: Catalytic activities in the TH of acetophenone derivatives

“…In recent times, the ruthenium(II) or rhodium(III) complexes of C 2 -symmetric bis(sulfonamide)-cyclohexane-1,2-diamine-RhCp* and chiral substituted aromatic monosulfonamide were synthesized and used as catalysts for ATH in isopropanol or water [17,18].…”

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

“…9 Recently, a number of asymmetric transfer hydrogenation (ATH) reports have appeared, using heterogenized or water soluble metal complexes, and sodium formate as the hydride source to get enantiopure chiral alcohols from aromatic prochiral ketones. 10 Addressing this, we have reported a C 2 -symmetric bis(sulfonamide)-cyclohexane-1,2-diamine ligand [(1), Figure 1 2 and their application in the ATH of twelve ketones with aqueous sodium formate. Ligands 2 and 3 are derived from (1R,2R)-cyclohexane-1,2-diamine and also from 9-oxo-9H-fluorene-2,7-disulfonyl dichloride (for 2) and fluorene-2,7-disulfonyl dichloride (for 3) (Figure 1).…”