Thieno analogues of kenpaullone have been synthesized using an established method. We investigated the effect of five structural analogues of kenpaullone on vincristine sensitive and resistant MCF7 (human mammary adenocarcinoma) cells. One analogue, 8-Bromo-6, 11-dihydro-thieno-[3′, 2′: 2, 3] azepino [4, 5-b] indol-5 (4H)-one (3a), showed an antiproliferative activity in the drug sensitive cell line that led to cell accumulation in G2/M ...