Reaction of 3-(R-methylidene)-2-ethoxylindolenines with <Emphasis Type="Italic">N,N</Emphasis>'-binucleophiles

Reactions of 3-isopropylidene- and 3-cyclohexylidene-2-ethoxyindolenine tetrafluoroborates with guanidine afford dihydropyrimido4,5-b]indole derivatives containing a hydroxy group, unlike analogous reactions of 3-arylmethylidene and 3-(dimethylamino)methylidene tetrafluoroborates.