| 97% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0 - 20℃; for 0.5h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 0 - 20℃; for 18h; |
|
| 95% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With tetrabutylammonium bromide; sodium hydroxide In dichloromethane at 0 - 20℃;
Stage #2: benzyl bromide In dichloromethane at 20℃; |
|
| 91% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide at 0℃; for 0.416667h; Inert atmosphere;
Stage #2: benzyl bromide In N,N-dimethyl-formamide at 0 - 20℃; for 17h; Inert atmosphere; |
Tri-O-benzyl-D-glucal (4)
A solution of D-glucal (4.458 g, 30.5 mmol) in DMF (200 mL) was cooled to 0 °C and then treated with sodium hydride (6.712 g, 167.8 mmol). The solution was stirred at 0 °C for 25 minutes, then treated with benzyl bromide (11.97 mL, 100.6 mmol) and allowed to warm to room temperature. After 17 hours, the solution was quenched with water (20 mL) and then extracted with diethyl ether (3 x 200mL). The organic fractions were combined, dried (MgSO4), filtered and concentrated to give the crude product as a yellow oil. Chromatography of the oil (9:1 hexanes:ethyl acetate) afforded 4 (11.51 g, 91%) as a white crystalline solid. The spectral data matched those reported previously.4 |
| 91% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 0.5h; Inert atmosphere;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 20℃; for 16h; Inert atmosphere; |
|
| 90% |
With sodium hydride In tetrahydrofuran; N,N-dimethyl-formamide at 60℃; for 4h; |
|
| 87% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In tetrahydrofuran; mineral oil at 0 - 20℃; for 1h; Inert atmosphere;
Stage #2: benzyl bromide With N,N,N-tributyl-1-butanaminium iodide In tetrahydrofuran; mineral oil at 35℃; for 24h; Inert atmosphere; |
|
| 75% |
With sodium hydride In tetrahydrofuran; N,N-dimethyl-formamide; mineral oil at 0 - 60℃; for 4h; Inert atmosphere; |
|
| 74% |
With sodium hydride In N,N-dimethyl-formamide for 12h; |
|
| 73% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at -10℃; for 0.5h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 20℃; Cooling; |
[0188] Solution of 2-deoxy-D-glucopyranose (1.46 g, 10 mmol) in DMF (15 mL) was prepared and cooled down to -10°C. Sodium hydride (60% suspension in mineral oil) (1.99 g, 50 mmol) was added and the mixture was stirred for 30 min. Benzyl bromide (6.85 g, 40 mmol) was added, the cooling bath was removed and the reaction mixture was stirred at room temperature until all substrate was converted into product. The mixture was cooled down to 0°C, and water (50 ml) was added slowly, followed by DCM (50 mL). Organic layer was separated, washed with water until neutral, then with brine, and dried over anhydrous sodium sulfate. Drying agent and solvents were removed and product was purified by low pressure column chromatography (LPC), using hexanes : ethyl acetate gradient (0 to 20% of EtOAc) for elution. [0189] Fractions contained product were pooled together, evaporated to dryness and dried under reduced pressure to give 3.03g of product. Yield 73%, [0190] *H NMR (CDC13, δ), ppm: 7.34-7.24 (m, 15 H, H arom.), 6.43 (dd, 1H, J = 6.1 Hz, J = 1.1 Hz, H-l), 4.88 (dd, 1H, J = 6.1 Hz, J = 2.7 Hz, H-2), 4.84 (d, 1H, J= 11.4 Hz, CH2Ph), 4.67-4.54 (m, 5H, CH2Ph), 4.22 (m,lH, H-3), 4.07 (ddd, 1H, J = 8.2 Hz, J = 4.7 Hz, J = 3.2 Hz, H-5), 3.87 (dd, 1H, J = 6.2 Hz, J = 8.6 Hz, H-4), 3.81 (dd, 1H, J = 4.9 Hz, J = 10.9 Hz, H- 6), 3.76 (dd, 1H, J = 3.1 Hz, J = 10.9 Hz, H-6'). |
| 73% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 0.5h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 20℃; |
1 3,4,6-Tri-O-benzyl-D-glucal.
Solution of glucal (1.46 g, 10 mmol) in DMF (15 mL) was prepared and cooleddown to 0°C. Sodium hydride (60% suspension in mineral oil) (1.99 g, 50 mmol) was added and the mixture was stirredfor 30 min. Benzyl bromide (6.85 g, 40 mmol) was added, the cooling bath was removed and the reaction mixture wasstirred at room temperature until all substrate was converted into product. The mixture was cooled down to 0°C (icebath), and water (50 ml) was added slowly, followed by methylene chloride (30 mL). Organic layer was separated, watersolution was extracted with methylene chloride (2 x 20 mL). Combined organic solutions were washed with water untilneutral, then with brine, and dried over anhydrous sodium sulfate. Drying agents and solvents were removed and productwas purified by column chromatography (SilicaGel 60 Merck), using hexanes; hexanes : ethyl acetate 40:1, 20:1 aseluents.[0075] Fractions contained product were pooled together, evaporated to dryness and dried under reduced pressureto give 3.03g of product. Yield 73%.[0076] 1H NMR (CDCl3, δ), ppm: 7.34-7.24 (m, 15 H, aromatic H), 6.43 (dd, 1H, J = 6.1 Hz, J = 1.1 Hz, H-1), 4.88 (dd,1H, J = 6.1 Hz, J = 2.7 Hz, H-2), 4.84 (d, 1H, J= 11.4 Hz, CH2Ph), 4.67-4.54 (m, 1H, CH2Ph), 4.22 (m,1H, H-3), 4.07(ddd, 1H, J = 8.2 Hz, J = 4.7 Hz, J = 3.2 Hz, H-5), 3.87 (dd, 1H, J = 6.2 Hz, J = 8.6 Hz, H-4), 3.81 (dd, 1H, J = 4.9 Hz,J = 10.9 Hz, H-6), 3.76 (dd, 1H, J = 3.1 Hz, J = 10.7 Hz, H-6’). |
| 68% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide at 0℃; for 0.5h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide at 20℃; for 15h; Further stages.; |
|
| 68% |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide at 0 - 20℃; for 1h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide at 20℃; |
1 Preparation of (2R,3S,4R)-3,4-bis(benzyloxy)-2-((benzyloxy)methyl)-3,4-dihydro-2H- pyran (A3)
To a stirred solution of compound A2 (1.5 g, 10.0 mmol, 1.0 equiv) in DMF (50 mL) was added NaH (1.8 g, 45 mmol, 4.5 equiv) at 0°C, and the mixture was stirred at rt. for 1 h. BnBr (7.7 g, 45.0 mmol, 4.5 equiv) was added and the mixture was stirred at rt. overnight. The reaction was quenched with NH4CI (aq.), then concentrated, the residue was taken up with EA, washed with water and brine, dried over Na2SO4. Concentration and purification by silica gel (PE-PE:EA=40: 1-30: 1) provided compound A3 as a white solid (2.81 g, yield: 68 %). |
|
With sodium hydride In N,N-dimethyl-formamide |
|
|
With sodium hydride |
|
|
With potassium hydroxide In dimethyl sulfoxide |
|
| 1.49 g |
With potassium hydroxide In dimethyl sulfoxide at 20℃; for 48h; |
|
|
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With N,N,N-tributyl-1-butanaminium iodide; sodium hydride In tetrahydrofuran at 0℃; for 0.25h;
Stage #2: benzyl bromide In tetrahydrofuran at 45℃; for 6h; Further stages.; |
|
| 10.8 g |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at 0℃; for 0.75h; Inert atmosphere;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil at 0 - 20℃; for 16h; Inert atmosphere;
Stage #3: With methanol In N,N-dimethyl-formamide; mineral oil Inert atmosphere; |
|
| 4.17 g |
With sodium hydride In N,N-dimethyl-formamide at 0℃; for 12h; Inert atmosphere; |
|
| 70 g |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide; mineral oil at 20℃; for 0.0833333h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide; mineral oil |
1 3,4,6-Tri-O-benzylo-D-glucal (2)
D-Glucal (0.184 mol) was dissolved in DMF (300 mL). The obtaine solution was cooled down to 20 C and NaH (60% suspension in mineral oil) (0.83 mol, 33.2 g) was added. After 5 min, benzyl bromide (0.83 mol, 97.5 mL) was added dropwise with vigorous stirring. The reaction mixture was stirred while the temperature was allowed to rise to ambient. Progress of the reaction was monitored by the TLC method. After the reaction was completed, acetic acid (0.278 mol, 16 mL) in water (100 mL) was added dropwise. The mixture was then diluted with water (500 mL) and the product was extracted with hexanes (2 300 mL). Combined organic solutions were washed with water (3 200 mL), and dried over anhydrous Na2SO4. The solids were filtered off and solvent was evaporated to dryness. The remaining crude product was purified by low-pressure column chromatography using hexanes-ethyl acetate gradient. Fractions containing product were pooled together and evaporated to dryness, and residual solvents were removed by additional drying with a highvacuum oil pump, resulting in 70 g of white crystalline product (2) (yield 92%). Analytical data are consistent with the literature. |
|
With sodium hydride In N,N-dimethyl-formamide at 0℃; for 10h; |
10. General procedure for benzylation/methylation (NaH method):
Starting material, unprotected sugar (500 mg), was dissolved in dry DMF and benzyl bromide/methyl iodide (1.2 equiv.) was added to it followed by addition of NaH (1.5 equiv.). The reaction was allowed to stir at 0oC for 10 h. The product was extracted with ethyl acetate, passed over sodium sulfate and dried under reduced pressure. Column purification gave the benzylated/methylated sugar in 83% yield. |
| 665 mg |
Stage #1: 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol With sodium hydride In N,N-dimethyl-formamide at 0℃; for 0.333333h;
Stage #2: benzyl bromide In N,N-dimethyl-formamide at 0℃; for 12h; |
|
|
With sodium hydride In N,N-dimethyl-formamide Inert atmosphere; |
|
|
With sodium hydride In N,N-dimethyl-formamide at 0 - 25℃; Inert atmosphere; |
|
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