When crepenynic acid and octadec-14-yn-17-enoic acid were converted to
4,4-dimethyloxazoline (DMOX) derivatives by the usual procedure. cons
iderable isomerization occurred. The former was converted in part to 7
-(5-pentyl-cyclohexadienyl)-heptadecanoate, as was confirmed by mass s
pectrometry, including preparation of a Diels-Alder adduct with 4-meth
yl-1,2,4-triazoline-3,5-dione. A mild procedure for preparation of dim
ethyloxazoline derivatives was therefore developed that did not cause
such artefact formation. The mass spectra of the dimethyloxazoline and
picolinyl ester derivatives of the two acids are described. (C) 1998
Elsevier Science Ireland Ltd. All rights reserved.