Synthesis of glyceryl glycosides related to A-type prymnesin toxins

Carbohydr Res. 2018 Jun 30:463:14-23. doi: 10.1016/j.carres.2018.04.008. Epub 2018 Apr 17.

Abstract

A suite of glycosylated glycerol derivatives representing various fragments of the glycosylated ichthyotoxins called prymnesins were chemically synthesised. Glycerol was used to represent a small fragment of the prymnesin backbone, and was glycosylated at the 2° position with the sugars currently reported to be present on prymnesin toxins. Neighbouring group participation was utilised to synthesise 1,2-trans-glycosides. SnCl2-promoted glycosylation with furanosyl fluorides gave 1,2-cis-furanosides with moderate stereocontrol, whilst TMSOTf promoted glycosylation with a furanosyl imidate gave a 1,2-cis-furanoside with good stereocontrol. The chemical synthesis of two larger glyceryl diglycoside fragments of prymnesin-1, glycosylated with α-ʟ-arabinopyranose and α-ᴅ-ribofuranose, is also described. As the stereochemistry of the prymnesin backbones at this region is undefined, both the 2R- and 2S- glycerol isomers were synthesised. The separated diastereoisomers were distinguished by comparing NOESY NMR with computational models.

Keywords: Algae; Glyceryl glycosides; Prymnesins; Prymnesium parvum; Toxins.

MeSH terms

  • Glycosides / chemical synthesis*
  • Glycosides / chemistry
  • Glycosylation
  • Models, Molecular
  • Molecular Structure
  • Polyketides
  • Pyrans / chemistry*
  • Stereoisomerism

Substances

  • Glycosides
  • Polyketides
  • Pyrans
  • prymnesin 1