Synthesis and cyclizations of 1-azapolyene derivatives

Imminium salts of enaminonitriles with polyenals gave stable 1-azapolyenes, which could be readily transformed to benzo- and indoloquinolizines in 1,6-electrocyclizations. Azatrienes and azatetraenes with formaldehyde and primary amines afforded pyrimido[6,1-a]isoquinolines.