Andrei Korostylev

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)

Chiral pyrophosphites—synthesis and application as ligands in Rh(I)-catalyzed asymmetric hydrogenation

Abstract Enantiopure pyrophosphites have been prepared for the first time based upon two independent synthetic pathways. The new ligands based on binaphthols, which are remarkably stable towards oxidation, were tested in the Rh(I)-catalyzed asymmetric hydrogenation of functionalized olefins, where up to 70% ee could be achieved.

Highly stereoselective hydrogenations—As key-steps in the total synthesis of statins

Statins are inhibitors of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMG-CoA reductase) and became the standard of care for treatment of hypercholesterolemia because of their efficacy, safety, and long-term benefits. They are administered as diastereo- and enantiomerically pure compounds. We summarize here two new approaches for the total synthesis of the most important representatives, atorvastatin, and rosuvastatin, based on highly stereoselective hydrogenations as key-steps.

Mechanistic and synthetic aspects of hydroboration with a simple atropisomeric ligand prepared from 1-(1'-(isoquinolyl)-2-naphthol

Abstract A novel triarylphosphite ligand has been prepared directly from both enantiomers of BINOL and a single enantiomer of 1′-(isoquinolyl)-2-naphthol. In one of the two cases cationic Rh complex proved to be reasonably effective in the asymmetric hydroboration of electron-poor styrenes. It was possible to identify binuclear reactive intermediates when the hydroboration pre-catalyst was examined in the presence of catecholborane at low temperatures.

Facile Preparation and Purification of Mono tert‐Butyl Malonate

Abstract Reaction of Meldrums acid with tert‐BuOH gives tert‐BuO2CCH2CO2H, which can be easily purified via its corresponding crystalline ammonium salt and subsequent acidification.

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.

Complexation properties of aminophosphites bearing phosphorus and nitrogen atoms included in six-membered cycles

Abstract A series of amino phosphites having phosphorus or/and nitrogen atoms, which are included in a six-membered cycle, has been synthesized. The presence of such cycles in these P,N-bidentate ligands has been shown to strongly influence the ways of their coordination with Rh(I) and Pd(II) atoms. The resulting chelate complexes have been found to be less stable when the six-membered chelate metalacycle formed and the initial cycle of the ligand molecule comprise a bicyclic system with the phosphorus or nitrogen atom being as a spiro atom.