Atroposelektywna synteza naturalnych chiralnych osiowo związków biarylowych. Część 1
Journal Title: Wiadomości Chemiczne - Year 2017, Vol 71, Issue 3
Abstract
In early twentieth century, it was already known that chemical compounds might be chiral without containing the chiral atoms. The presence of the stereogenic center is a sufficient but not necessary condition that the molecule appears in two forms which are mirror images. In certain cases, the limit of free rotation in the molecule may result in asymmetry, e.g. inhibition of rotation around single bond leads to axial isomers. This is the kind of conformational isomerism, which according to the nomenclature is called atropisomerism [1, 2]. The most often optically active molecules without stereogenic atoms, possessing an axial chirality are biaryls, which are commonly found in nature. In most cases, pharmacological activity of biaryls is associated with the presence of axial chirality (Figs 1, 2; Scheme 1) [1–14]. Generally chiral biaryls are divided into bridged biaryls (Scheme 4–6) [15–24], and biaryls, which do not contain the additional ring (Scheme 2, 3) [25–33]. The thermal stability of both enantiomeric/diastereomeric forms is an essential precondition for atropisomerism. For a given temperature, conformationally stable isomers may coexist when their a half-life is at least 1000 s, which gives the minimum energy barrier of 93 kJ mol–1at 300 K. Chiral biaryls can be achieved by either desymmetrization of stable but achiral biaryls by modifying one of the groups on the aromatic moiety (Scheme 7–9) [1, 34, 35], or by dynamic kinetic resolution of racemic mixtures of the conformationally unstable chiral substrates. The synthesis of the chirally stable biaryls from the chiral labile substrates is most frequently the result of the extra substituent addition (Scheme 10) [36], and formation or cleavage of a bridge (Scheme 11–16) [37–54]. The axially chiral biaryls can also be obtained in the atroposelective transformation of the alkyl substituent of the arene ring into a second aromatic ring in the presence of an organometallic catalyst (Scheme 17, 18) [55, 56].
Authors and Affiliations
Renata Kołodziejska, Agnieszka Tafelska-Kaczmarek
Keywords
Related Articles
- EP ID EP568473
- DOI -
- Views 198
- Downloads 0
Alkaloidy kory chinowej : małe cząsteczki, które wiele mogą
Cinchona alkaloids comprising quinine, quinidine, cinchonidine and cinchonine as the major members constitute a unique class of quinoline alkaloids with tremendous impact on human civilization (Section 1). The odyssey of...
Zastosowania biologiczne tetrazoli i ich pochodnych
Due to the wide range of applications of tetrazoles, in recent years the number of publications and patents describing the synthesis, structural and physicochemical studies of compounds that contain tetrazole fragments i...
Wpływ montmorylonitu na właściwości reologiczne wodnych dyspersji karboksymetyloskrobi
Water dispersions are usually a colloidal system in which one of the phases is highly dispersed in a second of a continuous nature, called a dispersion medium (in this case it is water). Dispersal is also called the proc...
Metody obliczania napięcia międzyfazowego z symulacji komputerowych
Interfaces have been recently a subject of profound interest for physicists, chemists and biologists because of the processes taking place in the interfacial region like adsorption, catalysis of chemical reactions etc. C...
Charakterystyka endogennych inhibitorów enzymów rozkładających enkefaliny
Management of acute and chronic pain has always been a key area of clinical research. Pain and stress stimulation may cause an increase in the level of endogenous opioids in the body. Endogenous enkephalins activate opio...