Iridium complexes of chiral diamines containing carbon and nitrogen stereocentres: synthesis, structure and evaluation as transfer hydrogenation catalysts

Catalytic sugar-assisted transfer hydrogenation with Ru(II), Rh(III) and Ir(III) halfsandwich complexes

“…The chiral induction of monosaccharide ligands is quite good and comparable to the first results of hydrogen transfer reactions with chiral 1,2-diamino complexes [20,32]. The Ir(III)-complex 28 (Table 4, Chart 2) [20] furnished with a C2-symmetric diamino ligand with two almost equivalent amino groups and a radialsymmetric pentamethyl-Á 5 -cyclopentadienyl ligand reveals the same results in transfer hydrogenation of acetophenone with low enantiomeric excess as complex 23 (Rh; Table 1, entry 19).…”

“…benzylidene-2,3-dideoxy-3-tosylamido-␣-D-glucopyranoside ligand (5, Chart 1), (S)-2,2 -diamino-1,1 -binaphthalene (6, Chart 1) and (R,R)-1,2,-diphenylethylenediamine (7, Chart 1) as ligands of Á 6 -arene-ruthenium(II), pentamethyl-Á 5 -cyclopentadienylrhodium(III) and pentamethyl-Á 5 -cyclopentadienyliridium(III) (8-25, Chart 1) were prepared by common methods [15][16][17][18][19][20][21] , and were recently published [22]. Such compounds with chelating nitrogen ligands are effectively used in catalysis, e. g. in water oxidation [23], intramolecular hydroamination of alkynes [24], Diels-Alder reactions [25], asymmetric Michael addition reactions [26], asymmetric hydrogenation [27,28], and transfer hydrogenation [29][30][31], reactions of ketones and imines.…”

“…The formerly unknown precursor complexes with methyl 2,3-diamino-4,6-O-benzylidene-2,3-dideoxy-␣-D-hexopyranosides (compounds 1-4, Chart 1), methyl 2-amino-4,6-OChart 1. Diaminomonosaccharides 1-4, methyl 2-amino-4,6-O-benzylidene-2,3-dideoxy-3-tosylamido-␣-D-glucopyranoside (5) and corresponding diamino derivatives (S)-2,2 -diamino-1,1 -binaphthalene (6) and (R,R)-1,2-diphenylethylenediamine (7) and their halfsandwich complexes of iridium(III), -rhodium(III) and ruthenium(II) (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) for transfer hydrogenation ([T-4-R] and [T-4-S] denote the absolute configuration of the metal center in a pseudo-tetrahedral environment following the CIP rules).…”

Asymmetric hydrosilylation, transfer hydrogenation and hydrogenation of ketones catalyzed by iridium complexes

“…The preformed or in situ prepared iridium complexes of the new chiral diamine 29 have been tested in the ATH of ketones in isopropanol in presence of KOtBu [36]. At 55 • C, excellent conversions (up to 100%) but moderate enantioselectivities could be achieved (see Scheme 23).…”

Iridium-Catalyzed Hydrogen Transfer Reactions

“…Several other enantiomerically pure bidentate ligands have been screened using [Ir (cod)Cl] 2 , including bis-oxazolines [48,49], amino oxazolines [50], N-heterocyclic carbenes [51], and diamines [52,53]. Examples where the enantioselectivity was in excess of 90% ee include the use of ligands 45, 46, and 47 [54][55][56] There has been a growing interest in the development of aqueous phase asymmetric transfer hydrogenation of ketones [57,58].…”