Total Synthesis and Structural Revision of Lucentamycin A

Lucentamycin A is a marine-derived peptide natural product
harboring
a unique 4-ethylidene-3-methylproline (Emp) subunit. The proposed
structure of lucentamycin A and the core Emp residue have recently
been called into question through synthesis. Here, we report the first
total synthesis of lucentamycin A, which confirms that the ethylidene
substituent in Emp bears an E geometry, in contrast
to the originally assigned Z configuration. Synthesis
of the desired (E)-Emp subunit required the implementation
of a novel strategy starting from Garner’s aldehyde.