a Istituto di Chimica Organica, Università di Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
b Istituto di Industrie Agrarie, Università di Bologna, Via S. Giacomo 7, 40126, Bologna, Italy
Abstract:
Addition of Yb(fod)3 to methyl oleate (cis) and methyl elaidate (trans) shifts the carboxylic lines of their 13C-NMR spectra to different extents; that of the cis isomer less than that of the trans isomer, as is to be expected.
On the same theoretical ground it can be anticipated that the opposite will occur for C-17: an effect that has been confirmed experimentally. The method is thus proposed as a means of aiding in the assignment of the cis and trans configuration in esters of fatty acids with one double bond.