Structural determination of molecular stereochemistry using VCD spectroscopy and a conformational code: Absolute configuration and solution conformation of a chiral liquid pesticide, (R)-(+)-malathion

✍ Scribed by Hiroshi Izumi; Atsushi Ogata; Laurence A. Nafie; Rina K. Dukor

• Book ID: 102073632
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 369 KB
• Volume: 21
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/chir.20793

✦ Synopsis

The absolute configuration and solution conformation of (R)-(1)-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. V