We are aware from the literature that conformationally constrained molecules often have a greater effect on biological properties when compared to the relatively flexible open-chain compounds.  On the basis of this hypothesis, we anticipated that conformationally constrained analogues of our open chain diamides may increase potency.  Structures 1 and 2 suggest that a ring formation using N₁ and C₄ would result in b-lactam 3.  With regard to the above, we envisioned that b-lactam 3 of the general structure would serve as a conformationally constrained analogue of our open-chain compounds (1 and 2) that have been shown to have anticancer activity.  In this paper, the biological evaluation and mechanism of action of our anticancer b-lactams related to 3 will be discussed.