Collect. Czech. Chem. Commun. 2000, 65, 1643-1652
https://doi.org/10.1135/cccc20001643

Sterically Crowded Heterocycles. XIII. An Insight Into the Absolute Stereochemistry of Atropisomeric (Z)-3-(Imidazo[1,2-a]pyridin-3-yl)prop-2-en-1-ones

Radek Pohla, Jan Sýkorab, Petr Maloňc, Stanislav Böhma,*, Bohumil Kratochvílb and Josef Kuthana

a Department of Organic Chemistry, Institute of Chemical Technology, Prague, 166 28 Prague 6, Czech Republic
b Department of Solid State Chemistry, Institute of Chemical Technology, Prague, 166 28 Prague 6, Czech Republic
c Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, 166 10, Prague 6, Czech Republic

This article is part of serial Sterically crowded heterocycles.

Abstract

The absolute configuration of the atropisomeric (Z)-3-(5-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one was evaluated to be R for the dextrorotatory and S for the laevorotatory enantiomers. The assignment is based on their two-step syntheses via atropodiastereoisomeric carbamates prepared from the corresponding atropodiastereoisomeric alcohols with (R)-(+)-α-phenylethyl isocyanate and by a complete X-ray space analysis of the quaternary triiodide obtained from the (R)-(+)-enantiomer. CD spectra and PM3 calculated heats of formation for selected compounds are discussed in relation to the found molecular configurations.

Keywords: Imidazo[1,2-a]pyridines; Atropisomerism; Axial chirality; Absolute configuration; X-Ray analysis; CD spectroscopy; PM3 method; Semiempirical calculations; Racemization barriers.

References: 26 live references.