Nitrilimines in 1,3-Dipolar Cycloaddition Reactions: Synthesis of New Derivatives of Condensed 1,2,4-Triazolo- Heterocycles and Dithiatriazaspiro[4,4]non-2-enone Derivatives

C-Alkyl-N-arylnitrilimines 2 react with some containing thiourea moieties compounds 3-9, and thioxothiazolidin-4-one derivatives 10, 11. The nitrilimines 2a,b cycloadd to C=S double bond to give spiro intermediates which undergo ring cleavage to yield the 1,2,4-triazolo fused heterocycles and dithiatriaza-spiro[4,4]non-2-enone derivatives.