Structure Assignment of Lucentamycin E and Revision of the Olefin Geometries of the Marine-Derived Lucentamycins

摘要

A new lucentamycin analog, lucentamycin E (>5), was isolated from the culture broth of the marine-derived actinomycete Nocardiopsis lucentensis, strain CNR-712. The absolute stereostructure of >5 was assigned by comprehensive analyses of NMR data and by application of the advanced Marfey’s method. The planar structure of >5 was analogous to lucentamycins A–D, whereas the olefin geometry of the 3-methyl-4-ethylideneproline moiety was found to be E, opposite to 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 (2S, 3R, E)-3-methyl-4-ethylideneproline.