Interhalogens (ICl/IBr) and AgOTf in thioglycoside activation; synthesis of bislactam analogues of ganglioside GD3.
The novel promoter system IX/AgOTf (X = Cl or Br) has been evaluated in the synthesis of two bislactam analogues of GD3. We have carried out two high-yielding galactosylations in 97% and 98% yield, respectively, using ICl/AgOTf, and four sialylations in 93%, 59%, 40%, and 44% yield, using IBr/AgOTf. The choice of interhalogen (IX) is determined by the donor type used in the glycosylation. We also report some mechanistic investigations leading to further optimization of the IX/AgOTf promoter system.
Meijer
Andréas
A
Organic and Bioorganic Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
Ellervik
Ulf
U
D002240:Carbohydrate Sequence; D005732:Gangliosides / Q000138:chemical synthesis* / Q000737:chemistry; D006219:Halogens / Q000737:chemistry*; D007769:Lactams / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D013055:Spectrophotometry, Infrared; D013865:Thioglycosides / Q000737:chemistry*
D005732:Gangliosides; D006219:Halogens; D007769:Lactams; D013865:Thioglycosides; C026226:ganglioside, GD3