Primary cycloadducts of 1,10-phenanthrolinium and phthalazinium phenacylides with DMAD

Primary cycloadducts cis-2 and trans-6 of monosubstituted cycloimmonium phe nacylides 1 and 5 with DMAD have been obtained for the first time. They iso merise stereo specifically and regiospecifically by prototropic rearrangeme nt to dihydro derivatives cis-3 and trans-7, respectively. The new heterocy clic system of pyrrolo[1,2-a][1,10]phenanthroline was illustrated by a seri es of derivatives (8a-f). The ethyl (8b) and isopropyl (8c) esters exhibit helical chirality by H-1 NMR. (C) 2001 Elsevier Science Ltd. All rights res erved.