The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors burkholdacs A and B were efficiently synthesized in a highly convergent and unified manner. The synthesis features the amide coupling of a D-valine-D-cysteine- or D-allo-isoleucine-D-cysteine-containing segment with a D-methionine-containing segment to directly assemble the corresponding seco-acids, key precursors for macrolactonization. Using the same methodology, 5,6,20-tri-epi-burkholdac A was also synthesized. HDAC inhibitory assays and cell-growth inhibition analyses of the synthesized depsipeptides demonstrated the potency order of this class of bicyclic depsipeptides as compared to the clinically approved depsipeptide FK228 (romidepsin). Novel structure-activity relationships within this class of compounds were also revealed.