Siamese depsipeptides: Constrained bicyclic architectures

The first members of a new class of depsipeptides with tartaric acid as the core unit, called Siamese depsipeptides, are described. These compounds were synthesized from a branched precursor in only one cyclization step. The structural manipulation of a natural bioactive depsipeptide (sansalvamide A) gives analogues with greater activity, and thereby provides additional information on structure-activity relationships (see structures).