Michał Rachwalski

Highly Efficient Asymmetric Simmons–Smith Cyclopropanation Promoted by Chiral Heteroorganic Aziridinyl Ligands

Enantiomerically pure heteroorganic catalysts, bearing a hydroxy moiety, a stereogenic sulfinyl group, and a chiral aziridine moiety, have proved highly efficient in the asymmetric Simmons–Smith cyclopropanation of allylic alcohols, which generates the desired products in high yields (up to 95 %) and with ee values up to 94 %. The effect of the stereogenic centers at the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the title reaction is discussed.

Highly Efficient Asymmetric Aziridination of Unsaturated Aldehydes Promoted by Chiral Hetero‐organic Catalysts

Optically pure hetero‐organic catalysts that bear a hydroxyl moiety, a stereogenic sulfinyl group, and a chiral amine moiety, are highly efficient in the asymmetric aziridination of unsaturated aldehydes and lead to the desired chiral products in high yields (up to 93 %) with enantiomeric excess values up to 92 %. The influence of the stereogenic centers at the sulfinyl sulfur atom and in the amine moiety on the stereochemical outcome of the title reaction is discussed.

Highly enantioselective asymmetric direct aldol reaction promoted by aziridine amides constructed on chiral terpene scaffold

Optically pure, diastereomeric aziridine amides built on the chiral skeletons of camphor, fenchone, and menthone have proven to be highly efficient ligands for enantioselective asymmetric direct aldol reaction in the presence of water and zinc triflate. Desired products were formed in moderate to high chemical yields (up to 95%) and with enantiomeric excess up to 99%. The influence of the stereogenic centers located at the aziridine subunit on the stereochemical course of the reaction is discussed.

Highly enantioselective asymmetric reduction of aromatic ketimines promoted by chiral enantiomerically pure sulfoxides as organocatalysts

ABSTRACT Optically pure hetero-organic organocatalysts, bearing a hydroxy moiety, a stereogenic sulfinyl group and a chiral amine moiety, have revealed high catalytic activity in the asymmetric reduction of various N-aryl ketimines leading to the corresponding chiral amines. Desired products were formed in high chemical yields (up to 95%) and with ee’s up to 97%. The influence of particular stereogenic centres on the stereochemical outcome of the reduction reaction is discussed. GRAPHICAL ABSTRACT

Synthesis and Evaluation of Biological Activities of Aziridine Derivatives of Urea and Thiourea

In the present paper, we report the synthesis and evaluation of in vitro antimicrobial activities of aziridine-thiourea derivatives. A series of aziridines in reaction with isocyanates and isothiocyanates to obtain urea and thiourea derivatives were used. The structures of all new products were confirmed based on spectroscopic data (1H-NMR, 13C-NMR, HR-MS). These compounds were screened for their in vitro antimicrobial activity against a panel of Gram-positive and Gram-negative strains of bacteria. Six of the tested compounds appeared to be promising agents against reference strains of Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. Subsequently, compounds exhibiting promising antibacterial activity were tested against twelve clinical isolates of S. aureus from three different sources of infection. The most bactericidal compounds (MIC = 16–32 µg/mL) showed better antibacterial activity against MRSA than ampicillin and streptomycin. The in vitro cytotoxicity analysis on L929 murine fibroblast and HeLa human tumor cell line using the MTT assay allowed us to select the least toxic compounds for future investigation.

Synthesis of chiral 1-(2-aminoalkyl)aziridines via the self-opening reaction of aziridine

A novel approach to the synthesis of optically pure 1-(2-aminoalkyl)aziridines via a nucleophilic ring-opening reaction of aziridine is presented. The reaction takes place under mild conditions in the presence of ZnBr2 with moderate chemical yields. The formation of 1-(2-aminoalkyl)aziridines, starting from optically pure NHaziridines, occurs selectively, leading to a single diastereoisomer.