Asymmetric allylboration and ring closing alkene metathesis: a novel strategy for the synthesis of glycosphingolipids.
A novel strategy for the synthesis of D,L-glucosylceramide 1, a member of the glycosphingolipid class of natural products is described. Reagent-controlled asymmetric Brown allylboration gave excellent stereochemical control in the construction of adjacent stereocenters in the sphingoid base portion of the molecule. The trans-configured double bond was obtained as a single geometrical isomer by use of silicon-tethered olefin metathesis employing the Schrock carbene [(CF3)2MeCO]2Mo(=CHCMe2Ph)(=NC6H3-2,6-i-Pr2++ +) and in situ PhLi-induced ring-opening of the intermediate 5,6-dihydro-2H-1,2-oxasiline followed by protodesilylation with TBAF in DMSO. The synthesis was completed by long chain amide formation and global deprotection.
Barrett
A G
AG
Department of Chemistry, Imperial College of Science, Technology and Medicine, London, UK. agmb@ic.ac.uk
Beall
J C
JC
Braddock
D C
DC
Flack
K
K
Gibson
V C
VC
Salter
M M
MM
D000475:Alkenes; D000498:Allyl Compounds; D001896:Boron Compounds; D005963:Glucosylceramides / Q000138:chemical synthesis; D006028:Glycosphingolipids / Q000138:chemical synthesis*; D010126:Ozone
D000475:Alkenes; D000498:Allyl Compounds; D001896:Boron Compounds; D005963:Glucosylceramides; D006028:Glycosphingolipids; D010126:Ozone