Sanyensin with\nan Unprecedented Architecture: An Effective\nStrategy from Discovery to Stereochemical Identification of Flexible\nNatural Products

Under the guidance of genome mining\ncombined with bioassay-coupled\nmetabolomic analyses, an unprecedented macrodiolide sanyensin (<b>1</b>), with two flexible macrolides fused by the rigid oxabicyclo[3.3.1]nonane\ncore, was isolated from the deep-sea-derived <i>Streptomyces</i> sp. OUCT16-30. The stereochemistry of <b>1</b> was established\nby NOEs (nuclear Overhauser effects), <i>J</i>-based configuration\nanalysis, Marfey’s analysis, and together with a newly introduced\nstereochemical study workflow, which greatly shortens the time to\nobtain correct conformations of flexible structures based on the NMR\nconstraints, thus leading to reliable quantum chemical calculations\nto establish the absolute configurations. This workflow is expected\nto have broad applicability for elucidating the stereochemistry of\nflexible natural products. The macrodiolide framework of <b>1</b> is proposed to be formed through a biocatalytic cyclodimerization,\nfollowed by a series of nonenzymatic reactions. This work leads to\nnew insights into the unexplored biosynthetic potential of deep-sea\nmicrobes and also provides a practical streamline for efficient mining\nof novel natural products, from discovery to stereochemical finalization.