Efficient Asymmetric Simmons-Smith Cyclopropanation and Diethylzinc Addition to Aldehydes Promoted by Enantiomeric Aziridine-Phosphines

During an implementation of current research, a set of optically pure chiral aziridines and aziridine imines bearing a phosphine moiety was prepared with high values of chemical yield. The above chiral heteroorganic derivatives were tested for catalytic utility as chiral ligands in asymmetric Simmons-Smith cyclopropanation and asymmetric diethylzinc addition to various aldehydes. Most of the desired products were formed in high chemical yields, with satisfactory values of enantiomeric excess (sometimes more than 90%) and diastereomeric ratios (in case of cyclopropanation reaction).

Azaheterocyclic diphenylmethanol chiral solvating agents for the NMR chiral discrimination of alpha-substituted carboxylic acids

A series of small-membered heterocycle probes, so-called azaheterocycle-containing diphenylmethanol chiral solvating agents (CSAs), have been developed for NMR enantiodiscrimination. These chiral sensors were readily synthesized were inexpensive and efficiently used for the chiral analysis of alpha-substituted carboxylic acids. The sensing method was operationally simple and the processing was straightforward. Notably, we propose (S)-aziridinyl diphenylmethanol as a promising CSA, which has excellent chiral discriminating properties and offers multiple detectable possibilities pertaining to the 1H NMR signals of diagnostic split protons (including 25 examples, up to 0.194 ppm, 77.6 Hz). Its ability to detect the molecular recognition of fluorinated carboxylic acids were further investigated, with a good level of discrimination via the 19F NMR spectroscopic analysis. In addition, an accurate enantiomeric excess (ee) analysis of the p-methoxyl-mandelic acid with different optical compositions have been calculated based on the integration of well-separated proton signals.

Enantiodiscrimination of carboxylic acids using the diphenylprolinol NMR chiral solvating agents

Enantiopure diphenylprolinols have been developed as effective and practical NMR chiral solvating agents for the enantiodiscrimination of diverse α-carboxylic acids.

Ionic tagged amine supported on magnetic nanoparticles: synthesis and application for versatile catalytic Knoevenagel condensation in water

Propylamine modified with imidazolium ionic moiety grafted onto magnetic nanoparticles (MNPs) was prepared and evaluated as a catalyst for Knoevenagel condensation in water at room temperature.