Elżbieta Wojaczyńska

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.

Monoimine derived from trans-1,2-diaminocyclohexane and ethyl glyoxylate: an intermediate in aza-Diels-Alder and Mannich reactions.

Novel enantiopure policyclic nitrogen heterocycles have been obtained in the diastereoselective aza-Diels-Alder or Mannich reaction of dienes with imine formed in situ from ethyl glyoxylate and (1R,2R)-diaminocyclohexane.

Sequential asymmetric dihydroxylation and sulfoxidation of homoallylic sulfides. Stereochemical aspects of the preparation of new trifunctional chiral building blocks

Abstract Products with three new stereogenic centers were generated via sequential asymmetric dihydroxylation and sulfoxidation of homoallylic sulfides. The non-racemic homoallylic sulfoxides were prepared using chiral, vanadyl-based catalytic system with e.e. of up to 85%. Subsequently, these compounds were dihydroxylated with AD-mix system and gave products of low d.e.s (up to 40%). Recrystallization of l -diastereomers furnished both enantiomerically pure 1-phenyl-4-phenylsulfinylbutane-1,2-diols (X-ray), which are new and useful chiral building blocks. Further oxidation at sulfur produced the corresponding enantiomers of 1-phenyl-4-phenylsulfonylbutane-1,2-diol.

Zinc complexes formed by 2,2′-bipyridine and 1,10-phenanthroline moieties combined with 2-azanorbornane: modular chiral catalysts for aldol reactions

Chiral scaffolds of 2-azabicyclo[2.2.1]heptane and 2-azabicyclo[3.2.1]octane were used for the construction of new modular catalysts containing complexing moieties pyridine, 2,2′-bipyridine and 1,10-phenanthroline appended by an imine linkage. The coordination abilities of the new ligands towards Zn(II) were investigated using NMR and UV spectroscopy. The plausible structures of the [ZnL2]2+ and [ZnLXn](2−n)+ complexes formed were established by comparison of the experimental and DFT-calculated NMR spectra. The catalytic application of the [ZnLXn](2−n)+-type complexes in the asymmetric aldol reaction of ketones with aromatic aldehydes produced an excess of the respective syn-aldols in up to >98% ee.

Monoimines derived from (1R,2R)-1,2-diaminocyclohexane in aza-Diels-Alder reaction: Synthesis and characterization of sulfur derivatives based on the 2-azanorbornyl skeleton

GRAPHICAL ABSTRACT ABSTRACT Enantiomerically pure bicyclic derivatives of 2-azanorbornane containing sulfonamide, amide, and thiourea functionalities were synthesized using aza-Diels-Alder reaction.

An Effective Deracemization of trans-1,2-Bis (phenylsulfenyl)cyclohexane

A chiral S, S-donating C2-symmetric ligand containing two stereogenic centers was prepared from rac-trans-1,2-cyclohexanediol. An effective deracemization of trans-1,2-bis(phenylsulfenyl)cyclohexane was achieved by the catalyzed enantioselective sulfoxidation, followed by the chromatographic separation of diastereomeric mono- and bis-sulfoxides. Subsequent recrystallization of enantiomerically enriched bissulfoxide and its final deoxygenation gave optically pure (1R,2R)-bis(phenylsulfenyl)cyclohexane.

Chiral pyrrolidine thioethers and 2-azanorbornane derivatives bearing additional nitrogen functions. Enantiopure ligands for palladium-catalyzed Tsuji-Trost reaction

An efficient procedure for the synthesis of new enantiopure pyrrolidine-based sulfides bearing additional nitrogen donors and secondary amines based on a bicyclic 2-azanorbornane skeleton was developed. Their application as ligands in palladium-catalyzed Tsuji-Trost reactions led to high yields and up to 82% ee.