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A Facile Method to Determine the Absolute Structure of Achiral Molecules: Supramolecular‐Tilt Structures
Author(s) -
Tejedor Rosa María,
Uriel Santiago,
Graus Sara,
Sierra Teresa,
Serrano José Luis,
Claramunt Rosa M.,
López Concepción,
PérezTorralba Marta,
Alkorta Ibon,
Elguero José
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201204197
Subject(s) - absolute configuration , enantiomer , supramolecular chemistry , molecule , chemistry , crystallography , vibrational circular dichroism , circular dichroism , absolute (philosophy) , stereochemistry , materials science , crystal structure , organic chemistry , philosophy , epistemology
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 ,12 H ‐5,11‐methano‐dibenzo[b,f][1,5]diazocine, Tröger′s base, ( R,R )‐ 1 , as a chiral compound of known absolute configuration.