Naphtho[2,1-h]isoquinolines: a new class of partially reduced polycyclic aromatic nucleus

Abstract

An efficient de novo synthesis of partially reduced naphtho[2,1-h]isoquinolines has been developed through base catalyzed ring transformation of 2-oxo-4-sec-amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by a carbanion, generated in situ from 1-substituted-4-piperidones in DMF and powdered KOH, in excellent yields. The effect of nitrogen insertion in the D ring of partially reduced benzo[c]phenanthrene on conformational changes has also been studied by X-ray diffraction analysis.