The reaction of the isocoumarin derivative cetylimino-3-methyl-1H-2-be
nzopyran-4-carbonitrile (1a) with aromatic ortho diamines provides ent
ry to the benzimidazo[2,1-a]isoquinoline and related systems. Various
conversions of the methyl and cyano groups in the tetracycles into ami
de, aldehyde and acid functions have been carried out, along with stud
ies of electrophilic nitration.