S. E. Lyubimov

New chiral phosphite ligands bearing sp2-nitrogen: complexation properties and palladium(II)-catalysed enantioselective allylic alkylation

Abstract New homochiral P , N -bidentate phosphite-type ligands containing sp 2 -nitrogen were synthesised and their complexation with Rh(I) and Pd(II) atoms was investigated. The X-ray crystal structure of one of the chelate chlorocarbonyl rhodium complexes was obtained. E.e.s of up to 85% were attained in the Pd-catalysed allylic substitution reaction using the new P , N -ligands.

Easily Accessible Chiral P,N-Bidentate Aryl Phosphites, Their Complexation and Application in Enantioselective Allylic Alkylation, Sulfonylation and Hydrosilylation

New chiral P,N-hybrid aryl phosphites have been obtained by one-step phosphorylation of amino and imino alcohols. Complexation of the new ligands with [Rh(CO)2Cl]2, [Pd(COD)Cl2] and [Pd(allyl)Cl]2 was found to give chelate complexes [Rh(CO)Cl(η2-P∩N)], [PdCl2(η2-P∩N)] and [Pd(allyl)(η2-P∩N)]+Cl−, respectively. With these new P,N-ligands, up to 82% ee enantioselectivity was achieved in the Pd-catalysed alkylation of ethyl 3-penten-2-yl carbonate with dimethyl malonate, up to 80% ee in the Pd-catalysed sulfonylation of methyl 3-penten-2-yl carbonate with sodium p-toluenesulfinate, and up to 50% ee in the Rh-catalysed hydrosilylation of acetophenone with diphenylsilane. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

New amino-, imino- and oxazolinophosphites based on 1,1′-bi-2-naphtol: coordination and catalytic properties

Abstract A series of the new chiral BINOL-based phosphite P , N -hybrid ligands was prepared. The coordination behavior of all the ligands was studied and the neutral complexes [Rh(CO)Cl(P ∧ N)] were synthesized in order to characterize a degree of the electronic non-symmetry of donating centers. Also the neutral and cationic complexes cis -[PdCl 2 (η 2 -P ∧ N)], cis -[PdCl 2 (η 1 -P ∧ N) 2 ], cis -[PdCl(η 2 -P ∧ N)(η 1 -P ∧ N)] + Cl − , [Pd(allyl)(η 2 -P ∧ N)] + X − (X − =Cl − , BF 4 − ) were obtained and characterized. The new P , N -hydrid ligands gave up to 81% ee in the enantioselective Pd-catalyzed alkylation of 3-penten-2-yl carbonate by dimethyl malonate and up to 60% ee in the Rh-catalyzed hydrosilylation of acetophenone and acetylferrocene by diphenylsilane.

Chiral phosphites derived from carboranes: Electronic effect in catalytic asymmetric hydrogenation

A series of new fine-tunable monodentate phosphite and phosphoramidite ligands based on carboranes have been synthesized and used for asymmetric Rh-catalyzed hydrogenation of prochiral olefins with the result of up to 99.8% ee. Dependence of the enantioselectivity on the electron-withdrawing or electron-donating properties of the carboranyl substituent has been studied.

The use of palladium nanoparticles supported on graphene oxide in the Mizoroki-Heck reaction

We have developed a convenient single-step method for producing palladium nanoparticles on the surface of graphene oxide by reducing palladium chloride with NaBH4. According to transmission electron microscopy data, palladium nanoparticles have a spheroidal shape; their sizes are 6–8 nm. The tests of immobilized palladium nanoparticles have shown that they exhibit high activity in the Mizoroki-Heck cross-coupling reaction.

Synthesis and antituberculosis activity of indole–pyridine derived hydrazides, hydrazide–hydrazones, and thiosemicarbazones

We describe the design, synthesis, and in vitro antimycobacterial activity of a series of novel simple hybrid hydrazides and hydrazide-hydrazones combining indole and pyridine nuclei. The compounds are derivatives of 1-acetylindoxyl or substituted indole-3-carboxaldehydes tethered via a hydrazine group by simple C-N or double C=N bonds with 3- and 4-pyridines, 1-oxide 3- and 4-pyridine carbohydrazides. The most active of 15 compounds showed MICs values against an INH-sensitive strain of Mycobacterium tuberculosis H37Rv equal to that of INH (0.05-2 μg/mL). Five compounds demonstrated appreciable activity against the INH-resistant M. tuberculosis CN-40 clinical isolate (MICs: 2-5 μg/mL), providing justification for further in vivo studies.

Synthesis and properties of pentacoordinated phospha derivatives of iso-leucinol A rare example of using of hydrophosphoranes as ligands in asymmetric catalysis

Abstract New bicyclic (1) and tricyclic (2a) hydrophosphoranes have been synthesized from iso-leucinol. Complexation of bicyclic hydrophosphorane 1 with [PdCl2(COD)], [PdCl2(RCN)2] and [Pd(allyl)Cl]2 has been found to give chelate products [PdCl2(L)] and [Pd(allyl)(L)]+Cl− containing an “open” form of the phosphorane. Tricyclic hydrophosphorane 2a, as well as its homologue 2b, forms metal complexes with P-monodentate binding of a hydrophosphorane, phosphoranide or “open” form of the ligand. Up to 74% ee has been achieved in the Pd-catalyzed alkylation of 1,3-diphenylallyl acetate with dimethyl malonate using 1 and 2a and 2b as chiral ligands.

An efficient chiral phosphitooxazoline ligand for Pd-catalyzed asymmetric allylic sulfonylation

The new chiral phosphitooxazoline ligand 1 has been synthesized and found to give up to 92% ee in the Pd-catalyzed asymmetric sulfonylation of 1,3-diphenylpropen-2-yl acetate with sodium p-toluenesulfinate.

Activity of palladium nanoparticles on graphene oxide in the Suzuki—Miyaura reaction

A convenient express method for obtaining palladium nanoparticles on the graphene oxide support was developed. The data of transmission electron microscopy and X-ray diffraction analysis indicated the formation of palladium nanoparticles with an average size of 2 nm. The obtained nanocomposite material showed high catalytic activity in the cross-coupling reaction of bromobenzene with phenylboronic acid. The efficiency of the catalyst increases when using a mixture of organic solvents with water.

New oxazoline-containing phosphoramidite ligand for palladium-catalyzed asymmetric allylic sulfonylation

New chiral oxazoline-containing phosphoramidite was synthesized and its complex formation with rhodium(i) and palladium(ii) was examined. The new ligand is a highly efficient chiral inductor (ee up to 92%) in palladium-catalyzed asymmetric sulfonylation of 1,3-diphenylallyl acetate with sodium p-toluenesulfinate.