TiCl4 catalyzed cleavage of (25R)-22-oxo-23-spiroketals. Synthesis of sapogenins with furostanol and pyranone E rings on the side chain

Steroids. 2019 Dec:152:108488. doi: 10.1016/j.steroids.2019.108488. Epub 2019 Sep 6.

Abstract

The regioselective opening of the F ring of 22-oxo-23-spiroketals 7a-d using TiCl4 in acetic anhydride yielded the novel furostanols 11a-d along with cholestanic derivatives 8a-d with pyranone E ring. The structures of the new derivatives thus obtained were established using one- (DEPT) and two-dimensional 1H, 13C NMR experiments (COSY, HSQC, HMBC, NOESY). The 22α-hydroxyl orientation in compounds 11a-d was proposed by comparison of the 13C chemical shifts with those of other aglycone members of this family, and confirmed by combined NOESY and X-ray diffraction analysis of compound 11a.

Keywords: 22-Oxo-23-spiroketals; Furostanols; NMR; Steroids; X-ray.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Furans / chemistry*
  • Glycosides / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Sapogenins / chemical synthesis*
  • Sapogenins / chemistry
  • Spiro Compounds / chemistry*
  • Sterols / chemistry*
  • Titanium / chemistry*

Substances

  • Furans
  • Glycosides
  • Sapogenins
  • Spiro Compounds
  • Sterols
  • furostanol glycoside
  • spiroketal
  • titanium tetrachloride
  • Titanium