Konstantin N. Gavrilov

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.

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.

Platinum(II) and palladium(II) complexes with 3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-5λ5-phosphaspiro[4,4]nonane

Chelate metal complexes have been synthesised by reacting [MCODCl 2 ] (M=Pd, Pt) and 3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-5λ 5 -phosphaspiro[4,4]nonane. The general formula of the products is cis -[MCl 2 L], where L is a P , N -bidentate coordinated P(III) form of the initial hydrophosphorane. The structure of the products was determined by IR, 1 H, 13 C, 14 N, 15 N, 31 P, and 195 Pt NMR spectroscopy, plasma and laser desorption mass spectrometry, sedimentation analysis, X-ray photoelectron spectroscopy and, in the case of platinum products, by single-crystal X-ray diffraction. A tendency of the complexes to reorganise in organic solvents was revealed. In the case of the palladium complex, the process is accompanied by an increase in the degree of nuclearity.

(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.

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.

Quincoridine-based aminophosphite ligands and their Rh(I) and Pd(II) complexes

New chiral P,N-bidentate ligands containing a quincoridine fragment with a configuration-stable N-donating center were obtained. Coordination of the ligands to Rh(I) and Pd(II) atoms was carried out. Chlorocarbonyl rhodium and dichloride palladium complexes were found to be cis-chelates with P,N-bidentate ligands.

Complexation of hydrophosphoranes: possible mechanism and coordination activity

Complexation of (4S,9S)-4,9-diethyl-2,11-dioxa-5,8-diaza-1l 5 -phosphatricyclo[6.3.0.0 1.5 ]undecane (1) and 3,3,8,8-tetramethyl1,6-dioxa-4,9-diaza-5l 5 -phosphaspiro[4,4]nonane (2) with [Rh(CO)2Cl]2; 2,3,7,8-dibenzo-1,6-dioxa-4,9-diaza-5l 5 -phosphaspiro[4,4]nonane (3) with [Rh(CO)2Cl]2 and [MCl2(COD)] (M Pd, Pt); (2S,7S)-2,7-dimethyl-1,4,6,9-tetraoxa-5l 5 -phosphaspiro[4,4]nonane (4) with [Rh(CO)2Cl]2 and [PdCl2(COD)] has been studied. The products have been characterized by 1 H-, 2 H-, 13 C-, 31 P-NMR, IR spectroscopy, laser desorption mass spectrometry and X-ray photoelectron spectroscopy. A possible mechanism for hydrophosphoranes complexation is discussed. A correlation between Lewis basicity and coordination activity has been found for ligands 1‐3. Phosphorane 4 was shown to coordinate by means of the P(III)-tautomer.

Phosphite derivatives of (2R)-2-pyrrolidin-1-yl-butan-1-ol: synthesis, chelation with rhodium(I) and testing in the palladium-catalysed allylic alkylation

A series of chiral phosphite-type ligands with pyrrolidine moieties was synthesised. The compounds form chelate complexes upon reaction with [Rh(CO)2Cl]2. The new ligands were tested in Pd-catalysed enantioselective allylic alkylation giving up to 61% ee under standard conditions.