Renata Siedlecka

Selective oxidation of primary hydroxy groups in prinary-secondary diols

Abstract The two-phase oxidation of primary-secondary diols with sodium hypochlorite, mediated by TEMPO, brings about selective oxidation at the primary position. Such 5 diols are oxidized to the corresponding hydroxyaldehydes.

Vanadium catalyzed enantioselective oxidation of sulfides: easy transformation of bis(arylthio)alkanes into C2 symmetric chiral sulfoxides

Abstract A facile and selective method for the title transformation is described. The two-phase oxidation of bis-sulfides with hydrogen peroxide catalyzed by vanadium complex of chiral Schiff base leads to the corresponding chiral mono- and bis-sulfoxides. In the case of 1,2-bis(arylthio)ethanes the respective optically active bis-sulfoxides are formed in up to over 95% e.e.

Chiral β-amino sulfoxides. Synthesis, configurational assignment and conformational analysis based on X-ray, CD, 1H NMR and theoretical calculations

Abstract Enantiomerically pure u and l β-amino sulfoxides have been easily obtained from the respective homochiral α-amino alcohols. The absolute configuration at the created stereogenic centre was assigned by CD spectra and by X-ray analysis. Conformational analysis of the title compounds was carried out using quantum chemical energy-geometry optimization. Thus established conformational behavior explained the strongly configuration dependent NMR spectral patterns observed for the u and l diastereomers.

A new and efficient route to homochiral γ-hydroxysulfoxides and γ-hydroxysulfones

Abstract Readily available (+)-( R )-1,3-diphenyl-3-phenylsulfanyl-propan-1-one 1 was oxidized to the corresponding sulfone and its reduction gave separable (1 R ,3 R )- and (1 S ,3 R )-1,3-diphenyl-3-phenylsulfonylpropan-1-ols. When 1 was reduced to the mixture of epimeric alcohols, subsequent reaction with three different sulfoxidation agents allowed the separation of all four diastereomeric 1,3-diphenyl-3-phenylsulfinylpropan-1-ols in diastereomerically pure form. The absolute configuration at the newly created stereogenic carbon was proved by chemical correlation, while the configuration of the sulfur centre of the phenylsulfinyl group was established by CD spectroscopy.

Substituted N -salicylidene β-aminoalcohols: preparation and use as chiral ligands in enantioselective sulfoxidation and conjugate addition

A high yielding synthesis of optically active 3,5-disubstituted salicylidene β-amino alcohols (6) is described. The catalytic use of D or L-N-(3-phenyl-5-nitrosalicylidene)valinol in enantioselective sulfoxidation (H2O2 / VO(acac)2) gives up to 95% e.e. Asymmetric conjugate addition of thiophenol to 2-cyclohexen-1-one catalysed by Ti(OPr-i)4 and 6 leads to maximum 31% e.e. in the product.

Monitoring Structural Transformations in Crystals. Part 15. Structural Changes in Crystals Caused by UV Radiation Despite the Lack of a Photochemical Reaction

Crystals of 3-benzoylbicyclo[2.2.1]heptane-2-carboxylic acid (C15H16O3) do not undergo the photochemical reaction, namely the Yang photocyclization, but they undergo UV radiation damage. The initial stages of this process were monitored by X-ray diffraction and structure analysis. The results show that the process is smooth and accompanied by the decrease of the overall scale factor, the certain increase of width of reflections, the increase of the cell parameters, intermolecular distances, atomic displacement parameters and the small changes in orientation of molecular fragments.Graphical Abstract

Practical Phase-Transfer Synthesis of N-(Ethoxycarbonyl)Phthalimide and Its Analogues

Abstract Potassium imides are N-acylated with ethyl chloroformate in the presence of tetrabutylammonium chloride to form the corresponding N-etyhoxycarbonyl derivatives, useful agents for N-protection of primary amines.

Sulphur-containing compounds: Structure, spectra, non-linearity. Experimental and theoretical study

Room-temperature absorption spectra in non-polar and polar solvents as well as the results of structural analysis of carbamic acid N-(1-phenylthio-methyl)-2-methyl-propyl t-butyl ester (C16H25O2NS, 1a) and phthalimide-N-(1-phenylthio-methyl)-propane (C18H17O2NS, 1b) are presented. The β-amino sulphide 1a crystallises in the tetragonal system, space group P41, with a = 10.380(1) A, b = 10.380(1) A, c = 16.390(1) A, a = B = y = 90°, while the β-amino sulphide 1b crystallises in the monoclinic system, space group P21, with a = 7.958(1) A, b = 13.333(1) A, c = 7.340(1) A, β = 93.08(3)°. The spectroscopic properties of these compounds were also evaluated using the approximate all-valence-electron method (GRINDOL) including configuration interaction (Cl) together with the Langevin dipole/Monte Carlo technique to represent the solvent effect. Molecular polarisabilities and hyperpolarisabilities (βvec) were calculated using the sum-over-states (SOS) method.