A very short route to fully aromatic 2,3,8,9- and 2,3,8,9,12-oxygenated benzo[c]phenanthridines
Abstract
Cyclisation of suitably substituted 2-benzylamino-2-phenylacetonitries proceeds by rearrangement, in sulphuric acid or anhydrous hydrogen fluoride, to give 3-aryl-1,2-dihydroisoquinolinones possessing all but two carbons of the benzo[c]phenanthridine ring system. These two carbon atoms are introduced in high yield by means of a modified Reformatski reaction and the resulting ester is cyclised in sulphuric acid, with concomitant dehydration and oxidation, to give the fully aromatic four-ring system in only four steps.