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

Primary cycloadducts cis-2 and trans-6 of monosubstituted cycloimmonium phenacylides 1 and 5 with DMAD have been obtained for the first time. They isomerise stereospecifically and regiospecifically by prototropic rearrangement to dihydro derivatives cis-3 and trans-7, respectively. The new heterocyclic system of pyrrolo[1,2-a][1,10]phenanthroline was illustrated by a series of derivatives (8a–f). The ethyl (8b) and isopropyl (8c) esters exhibit helical chirality by 1H NMR.