206 H. Bartsch, Th. Erker and G. Neubauer Vol. 26 EXPERIMENTAL All melting points are measured with a Kotier hot-stage apparatus and are uncorrected. Mass spectra were recorded on a Varian MAT-311 in- strument (70 eV) and nmr spectra on a Bruker AC 80 spectrometer (80 MHz) using TMS as internal standard in deuteriochloroform unless otherwise stated. Ir spectra (potassium bromide) were obtained on a Jasko IRA-1 instrument. 2,4-Dihydro-l#-imidazo[2,l-cIl,4] ...