The cycloadducts 3, 5, and 7, readily available from methoxy-substituted 3-vinylindoles 1 and 2, were dehydrogenated with DDQ to the coplanar [a]-anellated carbazoles 4, 6, and 8. Compound 4a, also characterized by X-ray structural analysis, shows significant cytotoxicity against K562 und RXF393 human tumor cell lines.