A facile method to determine the absolute structure of achiral molecules: supramolecular-tilt structures.
PMID 23463532 · Chemistry (Weinheim an der Bergstrasse, Germany) · 2013 · DOI 10.1002/chem.201204197
Authors: Rosa María Tejedor; Santiago Uriel; Sara Graus; Teresa Sierra; José Luis Serrano; Rosa M Claramunt; Concepción López; Marta Pérez-Torralba; Ibon Alkorta; José Elguero
Abstract
Achiral compounds 4-methoxy-4-(p-methoxyphenyl)cyclohexanoneethylene ketal (2), 4-hydroxy-4-(p-methoxy phenyl)cyclohexanoneethylene ketal (3), and 3,5-dimethyl-4-nitropyrazole (4) crystallized in chiral structures and the samples showed an enantiomeric excess. We have determined the absolute structures of these compounds by using X-ray diffraction with copper radiation at low temperatures. Moreover, we have also established the prevalent absolute structures in these samples, by comparing their calculated and solid-state vibrational circular dichroism (VCD) spectra. The consistency of this method was confirmed by using (R,R)-2,8-diiodo-4,10-dimethyl-6 H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, Tröger's base, (R,R)-1, as a chiral compound of known absolute configuration.
Circular Dichroism; Cyclohexanones; Molecular Structure; Pyrazoles; Stereoisomerism; X-Ray Diffraction
Cite
Rosa María Tejedor; Santiago Uriel; Sara Graus; Teresa Sierra; José Luis Serrano; Rosa M Claramunt; Concepción López; Marta Pérez-Torralba; Ibon Alkorta; José Elguero. A facile method to determine the absolute structure of achiral molecules: supramolecular-tilt structures. Chemistry (Weinheim an der Bergstrasse, Germany) (2013). PMID 23463532. DOI 10.1002/chem.201204197.