Synthesis of Swinhoeisterol A, Dankasterone A and B, and Periconiastone A by Radical Framework Reconstruction

J Am Chem Soc. 2020 Jan 8;142(1):104-108. doi: 10.1021/jacs.9b12899. Epub 2019 Dec 27.

Abstract

A switchable radical framework reconstruction approach to structurally unique 13(14 → 8),14(8 → 7)diabeo-steroid swinhoeisterol A was developed. The conversion of an ergostane skeleton proceeded through the intermediacy of a 13(14 → 8)abeo-framework as present in the dankasterone and periconiastone family of natural products and features a β scission of a 14-alkoxy radical with concomitant generation of the C8-C13 bond. From this intermediate, and dependent on the conditions employed, the cascade continues with a Dowd-Beckwith rearrangement and leads to the formation of the 13(14 → 8),14(8 → 7)diabeo-framework of the swinhoeisterol class of natural products. The synthesis of these frameworks then allowed for efficient access to swinhoeisterol A (1), dankasterone A (Δ4-2), dankasterone B (2), and periconiastone A (3).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Ergosterol / chemical synthesis*
  • Free Radicals / chemistry
  • Humans
  • Steroids / chemical synthesis*

Substances

  • Free Radicals
  • Steroids
  • periconiastone A
  • swinhoeisterol A
  • Ergosterol