Syntheses of oligomannosides in solution and on a soluble polymer support: a comparison

The α-(1→6)-linked and the α-(1→2)-linked linear mannotetraose glycosides 3 and 4, respectively, and the branched mannopentaoside 2 [R = CH2(CH2)2CH2Cl] were synthesised by conventional methods in solution, using trichloroacetimidate donors, and the products were obtained in 39%, 42% and 40% overall yield, respectively. For comparative purposes, the same two linear tetrasaccharides were prepared by use of MPEG as a soluble polymer support, the yields being 34% and 14%, respectively. An attempted MPEG-supported synthesis of the branched pentasaccharide was unsuccessful. The merits and shortcomings of oligosaccharide syntheses on MPEG are discussed.

The illustrated tetramer and an analogous 1,2-linked compound were synthesised in solution and on a soluble polyethyleneglycol support. A branched pentomannose was obtained by solution methods but not on the polymer.Figure optionsDownload as PowerPoint slide