Total Synthesis of the Bicyclic Depsipeptide HDAC Inhibitors Spiruchostatins A and B, 5′′-<i>epi</i>-Spiruchostatin B, FK228 (FR901228) and Preliminary Evaluation of Their Biological Activity
Julia–Kocienski olefination of a 1,3‐propanediol‐derived sulfone and a L‐ or D‐malic acid‐derived aldehyde to access the most synthetically challenging unit, (3S or 3R,4E)‐3‐hydroxy‐7‐mercaptohept‐4‐enoic acid, present in a D‐alanine‐ or D‐valine‐containing segment; ii) a condensation of a D‐valine‐D‐cysteine‐ or D‐allo‐isoleucine‐D‐cysteine‐containing segment with a D‐alanine‐ or D‐valine‐containing