The NMR spectra were recorded with a Varian T-60 spectrometer. The variable-temperature NMR experiment was carried out by using a Varian XL-200 spectrometer. All chemical shifta are expressed as parts per million (6) from internal tetramethylsilane. The mass spectrum of methyl N-(phenylethy1)-formimidate was measured with a Varian MAT 311A spedrometer at 70 eV and an ion-source temperature of 140 OC. A meaningful spectrum could only be ...
