Cyclohexyl isocyanide reacts with dimethyl acetylenedicarboxylate to give a mixture of cyclopenta[b]pyridine derivatives, azaspirononatriene derivative and the azabicyclononatriene. It reacts with dialkyl acetylenedicarboxylates to form 1:1 intermediate which on facile addition to 1-benzylisatin and tryptantrin yields highly functionalized novel unsaturated γ-spiroiminolactones.