Optically Pure Aziridinyl Ligands as Useful Catalysts in the Stereocontrolled Synthesis

The synthesis of optically pure compounds remains a challenge in modern organic chemistry due to the great importance of single stereoisomers in the pharmaceutical, food, flavor, and fragrance industries. The crucial factor influencing the chemical yield and stereoselectivity of asymmetric reactions is the use of the appropriate chiral catalyst. Recently there has been a growing interest in the synthesis and modification of various chiral amine-functionalized compounds - especially aminoalcohols - to check their catalytic activity in various asymmetric reactions. On the basis of very few literature reports, it can be seen that aziridine-containing ligands exhibit a very high efficiency in reactions with organozinc reagents. In the existing review articles, this group of compounds has been described only randomly. The aim of the present paper is to review systematically the advances in the applications of chiral aziridine-containing derivatives as highly efficient catalysts in asymmetric synthesis, including also the results from our research group. In this review article, diverse aziridine-containing ligands such as aziridine alcohols, bis-aziridines, aziridine carbazides, and aziridine pyridines are described. The main attention is focused on the catalytic activity of the aforementioned ligands in the asymmetric reactions such as the addition of diethyl- and phenylethynylzinc to carbonyl compounds (aldehydes, enones), asymmetric allylic alkylation, direct asymmetric aldol condensation, nitroaldol (Henry) reaction, cyclopropanation and others.