The synthesis of a new class of stable coloured azomethineylides 3 derived from 3,4-diazanorcaradienes is reported, which under acid catalysis are transformed to again coloured stable azomethineylides 4 containing a five-membered 1-aza-1,3-cyclopentadiene skeleton. Azomethineylides 3 in boiling methanol rearrange to 3,5-diazahomotropilidenes 8 in good yields.