5. Glycosylation with chloroethanol acceptor (direct route) 2-Chloroethyl 2,2,3,3'4',6,6'-Hepta-O-acetyl-B-D-lactopyrano
Posted: Mon May 23, 2022 12:11 am
- 5 Glycosylation With Chloroethanol Acceptor Direct Route 2 Chloroethyl 2 2 3 3 4 6 6 Hepta O Acetyl B D Lactopyrano 1 (129.64 KiB) Viewed 12 times
b) Write the reaction formula for this experiment
c) Give a full detailed mechanism (including curly arrows, by products, etc) for this experiment
5. Glycosylation with chloroethanol acceptor (direct route) 2-Chloroethyl 2,2,3,3'4',6,6'-Hepta-O-acetyl-B-D-lactopyranoside (4) HO. CI OAC LOAC ACO ACO LOAC BF3 Et₂0 AcO- DCM OAc Compound MW (g/mol) eq n (mmol) d (g/ml) Sugar 780.94 1 2-chloroethanol 80.51 4 1.20 BF3 Et₂O 141.93 5.5 1.15 1.33 DCM 84.93 Apparatus: 100 ml round bottom flask, N₂ atmosphere Reaction temperature: RT Reaction time: TLC: EtOAC/Tol 2:1 Reaction molarity: 0.25 M Sugar and 2-chloroethanol are dissolved in dry DCM and put on ice. BF 3 Et₂O is added dropwise to the reaction mixture over 15 minutes, then allow flask to attain RT. When TLC shows complete conversion of the starting material, the solution is diluted with DCM (25 ml) and poured onto ice water (50 ml). The org. layer is separated (lower fraction!) and washed with water, sat. aq. NaHCO3 and sat. aq. NaCl. The org. layer is dried over MgSO4, filtered and concentrated in vacuo. Purification via chromatography using EtOAc/Tol 2:1. AcO- OACACO- C28H38019 678.5899 OAC OACACO- LOAC m (g) 5 OAC C28H39CIO 18 699.0515 V (ml)