Synthesis of the glycogen-like glucan isolated from P. boyii
a) i. 10% TFA in DCM, 0 °C, 1 h; ii. Ac2O, Py (67: 89%, 2 steps; 71: 98%, two steps; 74: 76%, 2 steps); b) mCPBA, DCM, −78 °C (98%); c) general glycosylation condition (70: 86%, α only; 73: 65%, α/β>15:1; 76: 70%, α only; 77: 73%, α/β=8:1); d) 20% NMP in DMF, 30 min (91%); e) DDQ, H2O:DCM=1:10 (92%); f) 10% TFA in DCM, 0 °C, 1 h (85%); g) i. NaOMe, MeOH; ii. H2, Pd(OH)2/C, tBuOH-H2O-AcOH=40:1:1 (83%, 2 steps).