1-Phenylsulfonyl-3-vinylindole can be prepared in good yield from the 3-ethyl derivative by a two-step bromination dehydrobromination sequence, As a 1,3-diene it undergoes [4+2]-cycloadditions with N-phenylmaleimide, p-benzoquinone, and dialkyl acetylenedicarboxylates to give derivatives of the 1,2,3,3a,4,5,10,10b-octahydropyrrolo[3,4-a]carbazole, 1,4,4a,5,6,11b-hexahydro-11H-benzo[a]carbazole, and carbazole ring systems, respectively.