E. A. Rastorguev

(S)-6-Bromo-BINOL-based phosphoramidite ligand with C1 symmetry for enantioselective hydrogenation and allylic substitution

(S)-6-Br-BINOL-derived phosphoramidite, a simple monodentate ligand with a stereogenic center at the phosphorus atom, was synthesized for the first time. This stereoselector generated a high level of enantioselectivity (80-95% ee) in the rhodium-catalyzed hydrogenation of alpha-dehydrocarboxylic acid esters and was also successfully employed in the asymmetric palladium-catalyzed allylic substitution of (E)-1,3-diphenylallyl acetate. The optical yield also showed significant dependence with reaction type: up to 70% ee for allylic amination, up to 75% ee for allylic sulfonylation, and up to 90% ee for allylic alkylation.

Asymmetric metal complex hydrogenation of 1-methyl-3,4-dihydroisoquinoline in the presence of amidophosphite ligand

A number of metal complex precatalysts, solvents, and additives were examined in the asymmetric hydrogenation of 1-methyl-3,4-dihydroisoquinoline in the presence of a chiral amidophosphite ligand. The enantioselectivity of hydrogenation of this substrate increased upon addition of iodine. The best result in the selective hydrogenation was observed when [Ir(COD)2]BARF was used as the precatalyst (COD is the cycloocta-1,5-diene, BARF is the tetrakis[3,5-bis(trifluoromethyl)phenyl]borate).

Application of a new amidophosphite ligand to Rh-catalyzed asymmetric hydrogenation of β-dehydroamino acid derivatives in supercritical carbon dioxide: Activation effect of protic co-solvents

New chiral amidophosphite ligand was synthesized and tested in the Rh-catalyzed asymmetric hydrogenation of (Z)-β-(acylamino)acrylates in protic solvents and supercritical carbon dioxide (scCO(2) ) The catalytic performance is affected greatly by the acidity of the solvents. Better enantioselectivity (up to 88% ee) was achieved in scCO(2) containing 1,1,1,3,3,3-hexafluoro-2-propanol, compared to neat protic solvents.

Asymmetric hydrogenation of (E)-dimethyl-2-acetamido-2-phenylvinylphosphonate in supercritical carbon dioxide in the presence of metal complex catalysts with phosphite-type ligands

Asymmetric hydrogenation of (E)-dimethyl-2-acetamido-2-phenylvinylphosphonate was performed in CH2Cl2 and supercritical carbon dioxide with the participation of Rh and Ir complexes with chiral phosphite-type ligands. Iridium catalysts dissolved in supercritical CO2 allow high enantioselectivity (up to 98.5% ee) and conversion to be obtained. Rhodium catalysts yield exclusively racemic reaction products.

Catalytic hydroformylation in the presence of rhodium complexes with homo- and heterocombination of two monodentate P-ligands

Activity of the complex containing both a phosphine and an amidophosphite ligand in the coordination sphere of rhodium was determined for the first time in the hydroformylation of styrene and oct-1-ene in supercritical carbon dioxide and benzene. The efficiency of this “mixed” heteroligand complex was compared with that of its analogs each containing the same two phosphine or two amidophosphite ligands.

Pd-Catalyzed asymmetric transformations involving P*-mono- and P*,N-bidentate diamidophosphites derived from (2S,3S)-N2,3-dimethyl-N1-phenylpentane-1,2-diamine

The synthesis of new P*-mono- and P*,N-bidentate diamidophosphites, containing 1,3,2-diazaphospholidine rings formed starting from (2S,3S)-N2,3-dimethyl-N1-phenylpentane-1,2-diamine, is described. Comparison of their efficiency in the Pd-catalyzed enantioselective allylation with (E)-1,3-diphenylallyl acetate showed that up to 97% ee was reached in the reaction involving dimethyl malonate as a C-nucleophile. The Pd-catalyzed desymmetrization of N,N′-ditosyl-meso-cyclopent-4-ene-1,3-diol biscarbamate gave up to 61% ee.

New P-chiral polyfluoroalkyl phosphorodiamidite ligand in asymmetric transformations catalyzed by palladium and copper complexes

Chiral phosphorus-containing ligands having polyfloroalkyl substituents may be used for the preparation of metal complex catalysts which could be recycled via phase separation [1]. Following the approach proposed by us previously [2], we synthesized a new P-chiral polyfluoroalkyl phosphorodiamidite L as shown in Scheme 1. The product was stable on storage and readily soluble in organic solvents. It was tested as chiral auxiliary in palladium-catalyzed enantioselective amination of 1,3-diphenylprop-2-en-1-yl acetate (I) with dipropylamine according to the procedure described in [3] (Scheme 2). In all experiments, a steadily high enantioselectivity level was reached (ee 91– 95%), regardless of the L/Pd molar ratio (1 : 1 or 2 : 1) and reaction medium. However, the substrate conversion turned out to be quite sensitive to the solvent nature: it did not exceed 32% in tetrahydrofuran but was almost complete in methylene chloride.

Hydroformylation of alkenes in supercritical carbon dioxide catalyzed by rhodium complexes with amidophosphite derivatives of carboranes

New carborane-containing amidophosphites are synthesized. Their effectiveness as ligands in the Rh-catalyzed hydroformylation of alkenes in supercritical carbon dioxide (SC-CO2) is tested. It is shown that the use of carboranylamidophosphites makes it possible to achieve a high degree of conversion at a low catalyst loading. In the SC-CO2 medium, the regioselectivity is higher as compared to the toluene medium.

Allyl substitution in a supercritical carbon dioxide medium catalyzed by complexes of palladium with phosphite-type ligands

Allyl amination and alkylation catalyzed by a palladium complex-phosphite-type-ligand catalyst in a supercritical carbon dioxide (SC-CO2) medium is studied. It is demonstrated that that the Pd-containing catalysts dissolved in SC-CO2 provide a high regioselectivity of the reaction and, thus, offer a convenient method for synthesizing allylamines.

The use of a new ionic phosphite ligand in the hydroformylation catalyzed by rhodium complexes: Effect of reaction media

A new method for the preparation of ionic phosphite ligands is developed. A first example of the use of this type of ligands in the hydroformylation catalyzed by rhodium complexes and conducted in organic solvents, an ionic liquid (IL), and supercritical carbon dioxide (SC-CO2) is described. It is shown that conducting the reaction in ionic liquid/supercritical carbon dioxide biphasic system may aid in increasing its rate.