Diastereomeric P,N-bidentate amidophosphites based on (S,S)- and (R,R)-hydrobenzoin as ligands in the Pd-catalyzed asymmetric allylation

New P,N-bidentate diastereomeric amidophosphite ligands were obtained by phosphorylation of (S)-2-[(phenylamino)methyl]pyrrolidine involving (4S,5S)- and (4R,5R)-2-chloro-4,5-diphenyl-1,3,2-dioxaphospholanes. Their efficiency in the Pd-catalyzed enantioselective allylic substitution was compared, it was found that the reaction involving (E)-1,3-diphenylallyl acetate and pyrrolidine gives up to 75% ee.     

Chiral 1,3,2-dioxaphospholane amidophosphite in the palladium-catalyzed enantioselective allylation

Phosphorylation of (S)-1,1,2-triphenylethane-1,2-diol furnishes cyclic P*-chiral amidophosphite, whose application as a ligand in the Pd-catalyzed allyl substitution in 1,3-diphenylallyl acetate provides the products ee up to 70%.     

Commuting differential operators and higher-dimensional algebraic varieties

Several algebro-geometric properties of commutative rings of partial differential operators (PDOs) as well as several geometric constructions are investigated. In particular, we show how to associate a geometric data by a commutative ring of PDOs, and we investigate the properties of these geometric data. This construction is in some sense similar to the construction of a formal module of Baker–Akhieser functions. On the other hand, there is a recent generalization of Sato’s theory, which belongs to the third author of this paper. We compare both approaches to the commutative rings of PDOs in two variables. As a by-product, we get several necessary conditions on geometric data describing commutative rings of PDOs.     

Magnetic Properties of Thin Metal-Polymer Films Prepared by High-Dose Ion-Beam Implantation of Iron and Cobalt Ions into Polyethylene Terephthalate

Thin metal-polymer composite films have been prepared by high-dose ion-beam implantation of Fe⁺ and Co⁺ ions into polyethylene terephthalate. The implantation of 40 keV ions at room temperature with doses from 2 · 10¹⁶ to 4 · 10¹⁷ cm⁻² have been performed, with the ion current density of 4 μA/cm². The effects of implantation dose on the film morphology and crystal structure have been investigated via atomic force and magnetic force microscopy and X-ray diffraction. The magnetic properties of synthesized structures have been studied by ferromagnetic resonance and with a vibrating-sample magnetometer. It was established that the properties of ion-implanted samples strongly depend on both the implantation dose and the type of implanted ions. The implantation dose at which the magnetic phase is formed for iron-implanted samples is significantly lower than that for cobalt-implanted ones. At high implantation doses due to polymer sputtering metal-containing layers are formed close to the sample surface for both ions. In this dose range the magnetic properties of implanted samples changed dramatically due to particle oxidation. The coercivity of synthesized layers reaches 180 and 300 Oe for iron- and cobalt-implanted samples, respectively. Authors' address: Vladimir Yu. Petukhov, Kazan Physical-Technical Institute, Sibirskii trakt 10/7, 420029 Kazan, Russian Federation     

Nonsimple relationships between the P-chiral diamidophosphite and the arylphosphine moieties in Pd-catalyzed asymmetric reactions: combinatorial approach and P,P-bidentate phosphine-diamidophosphites

A small family of P,P^∗-bidentate C₁-symmetric ligands containing 1,3,2-diazaphospholidine rings with stereogenic phosphorus atoms has been prepared. Palladium catalytic systems with these phosphine-diamidophosphites afforded 95% and 63% ees in asymmetric allylic substitution and desymmetrization processes, respectively. The influence of the nature of both the phosphine and diamidophosphite moieties of these compounds on the enantioselectivity is discussed. The ‘mixed-ligand approach’ in Pd-catalyzed asymmetric allylation with participation of some new P^∗-monodentate diamidophosphites and PPh₃ is also considered.     

Pd-Catalyzed asymmetric allylation involving bis(diamidophosphite) based on the salen-type chiral diamine

Russian Chemical Bulletin - New bis(diamidophosphite) ligand with stereogenic phosphorus atoms in the 1,3,2-diaza-phospholidine rings was synthesized based on (1R,2R)-[N,...     

On some questions related to the Krichever correspondence

We investigate various new properties and examples of the two-dimensional and one-dimensional Krichever correspondence.     

Asymmetric Pd-catalyzed allylic amination of 1,3-diphenylallyl acetate with dipropylamine in ionic and molecular solvents

Asymmetric catalytic allylic amination of 1,3-diphenylallyl acetate with dipropylamine in an ionic liquid, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, and in THF and CH₂Cl₂ in the presence of palladium complexes of P-monodentate phosphite and phosphoramidite derivatives of S-1,1′-bis-2-naphthol was carried out. This gave a product with ee of up to 65%. The level of asymmetric induction is retained after three catalyst cycles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2478–2481, November, 2005.     

Complexation and Pd-Catalyzed Asymmetric Allylation with Participation of Chiral Ferrocenyliminophosphites

Chiral ferrocene-containing iminoarylphosphite ligands based on 4,4-dimethoxy-6,6-di-tert-butyl-biphenyldiol-2,2 and their chelate complexes with Rh(I) and Pd(II) were synthesized for the first time. They were shown to be perspective reagents in the reactions of asymmetric allyl substitution. The Pd-catalyzed alkylation of 1,3-diphenylallylacetate with dimethyl malonate results in a 87% enantiomer excess (ee), while in sulfonylation of 1,3-diphenylallylacetate with sodium para-toluenesulfinite, this figure amounts to 67%. The results obtained were compared with coordination and catalytic efficiency of a less sterically hindered ferro-cenyliminophosphite based on pyrocatechol. The compositions and structures of new compounds were determined by the ¹H, ¹³C, ³¹P NMR, IR, mass spectrometry (EI, FAB, and electrospray techniques), and elemental analysis.