SummaryOn treatment with pharmaceutically important primary 1,3-diamines 2 and 8 as well a. o-aminobenzenesulfonamides 13-15. homophthalaldehyde (1) yields the intensely blue fluorescent, heteroanellated isoquinolines 5 and 9, as well as moderately fluorescent isoquinobenzothiadiazines 1 6 1 8 .