The title compounds (14 and 15) were obtained by the condensation of a 2- or 3-furaldehyde derivative (prepared from 2-methylfuran) with 2-amino-1-methyl-2-imidazolin-4-one (6) or -5-one (7). Most products from 6 contained the (E)- and (Z)-isomers in comparable amounts; in those from 7, the (Z) -isomer generally predominated. The isomers were distinguished by their H-1 and C-13 NMR spectra, in particular by the three-bond coupling between the carbonyl carbon and the olefinic hydrogen. This led to configurational reassignment of some previously reported analogues.