Cyclooctyne underwent 1,3-dipolar cycloaddition with pyridinium bis(methoxy
-carbonyl)methylides to afford the corresponding indolizines (8-methoxycarb
onyl-7-azatricyclo[188.8.131.52(2,7)]pentadeca-1,3,5,8-tetraenes) in good to mod
erate yields, Some molecular orbital considerations are also described on t
his reaction compared with the results on the reaction of pyridinium dicyan
omethylides with cyclooctyne.