| Abstract: | With the intention that annulation of carbo- or heteroaromatic rings at the 1,2-positions can activate 3-cyanoindolizines as 1,3-dipolar species, 6-cyanobenza]indolizines, pyridazino4,5-a]indolizines and 5-cyano-1,3-diphenylthiopheno3,4-a]indolizine were prepared. 6-Cyanobenza]indolizines smoothly -underwent 1,3-dipolar cycloaddition on to dibenzoylacetylene and diacetylacetylene to afford the corresponding indolizino3,4,5-ab]isoindoles, whereas 5-cyano-1,4-diphenylpyridazino4,5-a]indolizine reacted with dimethyl acetylenedicarboxylate to give the 1:2 adduct. Only a 3% yield of 5-cyano-1,3-diphenylthiopheno3,4-a]indolizine formed upon phosphorus pentasulfide treatment of 1,2-dibenzoyl-3-cyanoindolizine. |
