Enantioselective Total Syntheses of Preussomerins: Control of Spiroacetal Stereogenicity by Photochemical Reaction of a Naphthoquinone through 1,6-Hydrogen Atom Transfer

We report the enantioselective total syntheses of preussomerins EG₁ , EG₂ , and EG₃ . The key transformation is a stereospecific photochemical reaction involving 1,6-hydrogen atom transfer to achieve retentive replacement of a C-H with a C-O bond, enabling otherwise-difficult control of the spiroacetal stereogenic center.

Enantioselective Total Synthesis of (-)-Spiroxins A, C, and D

Spiroxins A, C, and D are metabolites that have been identified in the marine fungal strain LL-37H248. Their unique polycyclic structures and intriguing biological activities make them attractive targets for the synthetic community. Based on a scalable enantioselective epoxidation of 5-substituted naphthoquinone, an oxidation/spiroketalization cascade, ortho-selective chlorination of the phenol unit, and oxime-ester-directed acetoxylation, an enantioselective total synthesis of (-)-spiroxins A and C and the first total synthesis of (-)-spiroxin D have been achieved.