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Structural determination of molecular stereochemistry using VCD spectroscopy and a conformational code: Absolute configuration and solution conformation of a chiral liquid pesticide, ( R )‐(+)‐malathion
Author(s) -
Izumi Hiroshi,
Ogata Atsushi,
Nafie Laurence A.,
Dukor Rina K.
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20793
Subject(s) - chemistry , absolute configuration , chirality (physics) , circular dichroism , stereochemistry , spectroscopy , vibrational circular dichroism , conformational change , crystallography , computational chemistry , physics , quantum mechanics , chiral symmetry breaking , nambu–jona lasinio model , quark
The absolute configuration and solution conformation of ( R )‐(+)‐malathion were determined by using vibrational circular dichroism spectroscopy and a fragment‐conformational search with a recently published conformational code. The determination of molecular stereochemistry was carried out without a conformational search using molecular mechanics calculations. Density functional theory calculations of the fragments of ( R )‐malathion, ethyl propionate, ( R )‐ethyl 2‐(methylthio)propanoate, ( R )‐diethyl 2‐(methylthio)succinate, and O,O,S ‐trimethyl phosphorodithioate were carried out, and the principal conformational features of the fragments were profiled. This fragment‐conformational search reduces the time needed for the selection of the predominant conformations for ( R )‐malathion and significantly improves the accuracy of the determination of absolute configuration. Chirality 21:E172–E180, 2009. © 2009 Wiley‐Liss, Inc.