Figure 3: Synthesis of Araf31 donor 3.
From: Total synthesis of mycobacterial arabinogalactan containing 92 monosaccharide units
(a) Synthesis of oligosaccharides 12 and 32; (b) Synthesis of diols 11 and 14; (c) Synthesis of heptasaccharide 10; (d) Synthesis of Araf31 donor 3 and 31-mer arabinan 34. Reagents and conditions: (1) TTBP, 4 Å MS, CH2Cl2, p-TolSCl, AgOTf, then 27, −78 °C to room temperature; (2) p-TolSCl, AgOTf, then 27, −78 °C to room temperature; (3) TBAF, AcOH, THF; (4) p-TolSCl, AgOTf, TTBP, 1-octanol, 4 Å MS, CH2Cl2, −78 °C; (5) TTBP, 4 Å MS, CH2Cl2, p-TolSCl, AgOTf, then 28, −78 °C to room temperature; (6) H2NNH2-AcOH, THF/CH3OH (10:1); (7) p-TolSCl, AgOTf, then 14, −78 °C; (8) TBAF, THF; (9) Bz2O, DMAP, pyridine, CH2Cl2, reflux; (10) TTBP, 4 Å MS, CH2Cl2, p-TolSCl, AgOTf, then 11, −78 °C to room temperature; (11) p-TolSCl, AgOTf, then 12, −78 °C to room temperature; (12) p-TolSCl, AgOTf, then 12 or 32, −78 °C to room temperature; (13) NaOCH3, CH3OH/CH2Cl2 (2:1); (14) Pd/C, H2, EtOAc/THF/1-PrOH/H2O (2:1:1:1). TBAF, tetra-n-butylammonium fluoride.
