We report the enantioselective total syntheses of preussomerins EG 1 , EG 2 , and EG 3 . The key transformation is a stereospecific photochemical reaction involving 1,6-hydrogen atom transfer to achieve retentive replacement of a CÀ H with a CÀ O bond, enabling otherwise-difficult control of the spiroacetal stereogenic center.

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.

Aiming at the enantioselective total synthesis of γ-rubromycin, we reported 1,2-naphthoquinone photochemical reaction as a promising solution to otherwise-difficult enantiocontrol of the single spiroacetal stereogenic center. The present study examined applicability of this approach to more functionalized substrates, which revealed viability dependence on the chromophore structure differing in the position and number of methoxy substituents.