This work describes the total synthesis of the alkaloid cenocladamide and a concise library of nine structural analogues aiming at their evaluation against the breast cancer cell line MDA-MB-231. The most promising compound (<b>3</b>; IC<sub>50</sub> = 6.6 μM) was also evaluated in a panel of seven breast cancer cell lines and two non-tumorigenic cell lines. We further conducted an initial investigation on the mechanism of action of analogue <b>3</b>, which lacks the endocyclic double bond when compared to cenocladamide. The present study presents the discovery of a cenocladamide analogue with interesting cytotoxic activity, which could be useful for further optimization towards new chemotherapeutic agents for breast cancer treatment.