Total Synthesis of (−)-Irciniastatin B and Structural Confirmation via Chemical Conversion to (+)-Irciniastatin A (Psymberin)

The total synthesis and structural confirmation of the marine sponge cytotoxin (−)-irciniastatin B has been achieved via a unified strategy employing a late-stage, selective deprotection/oxidation sequence that provides access to both (+)-irciniastatin A (psymberin) and (−)-irciniastatin B.