This review deals with structure-activity relationships, conformational analysis of teleocidins and creation of new active compounds for the determination of active conformation of teleocidins. Phorbol esters containing 12-O-tetradecanoylphorbol-13-acetate (TPA) and teleocidins which are classified as TPA-type tumor promoters exhibit potent tumor-promoting activity as well as many important biological activities connected with cell prolification and cell differentiation. Teleocidins are known to exist in an equilibrium between two conformational states in solution, the twist and the sofa forms. The low energy barrier between the two conformers makes it difficult to identify the mode of interaction of these promoters with common macromolecular targets. Design and synthesis of molecules having a new skeleton (benzolactams) and producing two conformations of teleocidins solve the problem. Benzolactams become the simplest molecule reproducing the conformation and activity of teleocidin, and will be a useful tool for the study of tumor-promotion and cell differentiation.