Nikolay S. Ikonnikov

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 ∧ Nue605)], cis -[PdCl 2 (η 1 -P ∧ Nue605) 2 ], cis -[PdCl(η 2 -P ∧ Nue605)(η 1 -P ∧ Nue605)] + Cl − , [Pd(allyl)(η 2 -P ∧ Nue605)] + 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.

New oxidovanadium(IV) complex with a BIAN ligand: synthesis, structure, redox properties and catalytic activity

Reaction of VCl3 with bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in air afforded [VOCl2(dpp-bian)] (1). The complex was characterized by IR and UV-vis spectroscopies and elemental analysis. The crystal structure of 1 was determined by X-ray diffraction (XRD) analysis. The vanadium atom is in a square-pyramidal OCl2N4 coordination environment. The cyclic voltammogram (CV) in dichloromethane reveals an irreversible oxidation process at +1.40 V (vs. Ag/AgCl) assigned to the V(IV)/V(V) couple, and two consecutive quasi-reversible one-electron reduction processes at −0.32 V and −1.05 V (vs. Ag/AgCl), respectively, assigned to the bian/bian−/˙ and bian−/˙/bian2− couples, followed by irreversible reduction at −1.6 V (vs. Ag/AgCl). The EPR spectrum of 1 in toluene shows a single 8-line signal typical for oxidovanadium(IV) complexes with d1 configuration. The magnetic behavior of 1 confirms the presence of one unpaired electron (μeff (330 K) = 1.67 μB), and the isolation of the paramagnetic centers. Application of 1 to oxidation of alkanes documented high catalytic activity under mild conditions. The kinetics and selectivity of alkane oxygenation by the 1/H2O2 and 1/PCA/H2O2 systems (PCA is pyrazine-2-carboxylic acid) were studied. The reaction is more efficient in the presence of PCA.