Cyano-substituted nitrile ylides

The cyano-substituted nitrile ylides 123 have been generated via 1,1-elimination reactions. For example, the benzyhdene derivative 122 (R=Ph) eliminated benzene on vapor phase pyrolysis to give 123 (R=Ph), which reacted via 1,5-electrocycli-zation [see also (66)] to give the isoindole 124 (41%) (67). In a similar way, 122 [R=(CH2)3CH=CH2] gave the corresponding nitrile yhde that reacted via intramolecular cycloaddition to give the pyrroline derivative 126. 

---