Structure Assignment of
Lucentamycin E and Revision
of the Olefin Geometries of the Marine-Derived Lucentamycins
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Abstract
A new lucentamycin analogue, lucentamycin E (<b>5</b>), was
isolated from the culture broth of the marine-derived actinomycete <i>Nocardiopsis lucentensis</i>, strain CNR-712. The absolute stereostructure
of <b>5</b> was assigned by comprehensive analyses of NMR data
and by application of the advanced Marfey’s method. The planar
structure of <b>5</b> was analogous to lucentamycins A–D,
whereas the olefin geometry of the 3-methyl-4-ethylideneproline moiety
was found to be <i>E</i>, opposite of that previously reported.
Consequently, a reinvestigation of the olefin geometries of the 3-methyl-4-ethylideneproline
residues of lucentamycins A–D showed that the olefin geometries
of the substituted proline functionalities must be revised to (2<i>S</i>,3<i>R</i>,<i>E</i>)-3-methyl-4-ethylideneproline
