A study of the donor properties of sialyl phosphites having an auxiliary 3-(S)-phenylseleno group.
Two phosphite sialyl donors, each having an auxiliary 3-(S)-phenylseleno group, were prepared and evaluated. The phenylseleno group was introduced via a new mode of generating phenylselenenic acid ('PhSeOH'). Although the sialyl donors provided fair yields (32-76%) of the desired sialosides in glycosylations of the reactive acceptor 1,2;3,4-di-O-isopropylidene-alpha-D-galactopyranose, no sialylated products could be obtained with less reactive acceptors. The presence of a 5-N-acetylacetamido group on the phosphite sialyl donor did not appear to improve its sialylating capability. The weak C-Se bond, possibly in combination with a steric hindrance, which disfavors alpha-nitrilium ion formation, seem to explain the unsuccessful sialylations of the less reactive acceptors.
Ercegovic
T
T
Chemical Center, The Lund Institute of Technology, University of Lund, Sweden.
Nilsson
U J
UJ
Magnusson
G
G
D005732:Gangliosides / Q000138:chemical synthesis; D009682:Magnetic Resonance Spectroscopy; D017905:Phosphites / Q000737:chemistry*; D064586:Selenic Acid; D018036:Selenium Compounds / Q000737:chemistry*; D012794:Sialic Acids / Q000737:chemistry*
D005732:Gangliosides; D017905:Phosphites; D018036:Selenium Compounds; D012794:Sialic Acids; D064586:Selenic Acid