2-Amino-N-benzyloxycarbonyl-2-deoxy-1-O-methyl--D-glycopyranoside 180[188]
The methylglycoside 180 was synthesized according to a procedure from Sofia et al.[188] in 49 % yield.
2-Amino-N-benzyl-N-benzyloxycarbonyl-3,4-O-benzyl-2-deoxy-1-O-methyl--D-glycopyranoside 181
Methylglycoside 180 (5 g, 15.27 mmol) and trityl chloride (8.5 g, 30.48 mmol) were stirred in pyridine (45 mL) for 2 d. Pyridine was removed under reduced pressure, the residue was dissolved in CH2Cl2 and washed with brine. The aqueous layer was extracted with CH2Cl2 (2x) and the combined organic layers were dried (MgSO4).
After filtration and removal of the solvent under reduced pressure the orange oil was used without purification.
NaH (60 % in mineral oil, 2.9 g, 85.9 mmol) was suspended in dry DMF (50 mL) and cooled to 0°C. BnBr (14.7 mL, 85.9 mmol) was added dropwise. The solution of crude tritylated methylglycoside in DMF (100 mL) was added dropwise and the reaction was stirred at rt for 3 h. MeOH was added, diluted with EtOAc and neutralized with acetic acid. The suspension was washed with water and the organic layer was dried (MgSO4), filtered and evaporated under reduced pressure to obtain a brown oil.
The crude product was dissolved in CH2Cl2 (150 mL), TFA (9.7 mL, 125.6 mmol) and tri-iso-propylsilan (4.8 mL, 22.84 mmol) were added and the reaction mixture was stirred for 1.5 h. The solvent was removed under reduced pressure and the residue was dissolved in CH2Cl2, washed with sat aq NaHCO3, dried (MgSO4), filtered and concentrated under reduced pressure. The brown oil was purified by FC (petroleum ether/EtOAc 5:1 to (8 mL) were added and the suspension was stirred at 80°C overnight. The suspension was filtered and washed with EtOAc. After removal of the solvent under reduced pressure, the residue was purified by FC (petroleum ether/EtOAc 3:1) yielding enolacetate 182 (4.07 g, 83 % over two steps) as an orange oil.
Rf = 0.40 (petroleum ether/EtOAc 3:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.41-7.89 (m, 21 H,
A solution of enolacetate 182 (2.43 g, 3.81 mmol) and HgSO4 (226 mg, 0.76 mmol) in 1,4-dioxane/5 mM H2SO4
2:1 (30 mL) was stirred at 80 °C for 24 h. The reaction mixture was extracted with CH2Cl2 and washed with water. The organic layer was dried (MgSO4) and concentrated. The residue was purified by
FC (petroleum ether/EtOAc 2:1) yielding 183 (795 mg, 34 %) as colorless foam.
Rf = 0.30 (petroleum ether/EtOAc 2:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.34-7.06 (m, 20 H,
To a solution of methyl glycoside 181 (5.02 g, 8.4 mmol) in dry toluene (32 mL) triphenylphosphine (4.40 g, 16.8 mmol) and imidazole (1.62 g, 23.8 mmol) were added. The reaction mixture was heated to 60 °C and I2 (3.0 g, 23.6 mmol) was added in portions. The reaction mixture was stirred at 80 °C for 3 h and evaporated under
CDCl3): [ppm] = 128.8-125.6 (CAr), 99.7 (C-1), 83.6 (C-5), 75.3 (CBn), 70.0 (C-4), 67.7 (CBn), 55.0 (CH3), 53.5 (CBn); 20.44 mmol) was added. The suspension was stirred for 1 d at rt. DMF was removed under reduced pressure and the residue was dissolved in EtOAc and washed with 1 M HCl, sat aq NaHCO3, brine and dried (MgSO4). The solvent was removed under reduced pressure and the residue was purified by automated FC (15 % to 100 % B in 8 min, 5 min 100 % B (A: petroleum ether, B: EtOAc) to afford alkene 195 (2.32 g, 82 %) as colorless oil.
With the help of an ozonizer, a mixture of ozone and oxygen was bubbled through the solution until it turned blue. The bubbling was continued for further 2 min. The ozonizer was turned off and oxygen was bubbled through the solution until it turned colorless again. To the cooled solution, dimethylsulfide (0.6 mL, 8.20 mmol) was added and the reaction mixture was allowed to warm to rt. The solvents were removed under reduced pressure and the residue was purified by FC (petroleum ether/EtOAc 5:1) yielding sugar lacton 196 (560 mg, 84
%) as colorless oil.
Rf = 0.24 (petroleum ether/EtOAc 5:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.35-6.89 (m, 20 H, Ar-H), 5.12-5.00 (m, 3 H, CH2), 4.87-4.57 (m, 4 H, CH2, H-1, H-2), 4.39-4.29 (m, 2 H, CH2), 4.21-3.90 (m, 3 H, CH2, H-3, H-4), 2.87 (s, 3 H, CH3); 13C NMR (100 MHz, CDCl3): [ppm] = 170.2 (C-5), 157.7 (C(O)OCH2Ph), 139.3-125.8 (CAr), 100.1 (C-1), 81.3 (C-4), 74.8-74.6 (C-3, CBn), 68.0 (CBn), 57.2 (C-2), 56.6 (CH3), 47.3 (CBn); RP HPLC: tr = 4.94
min (EC 125/4 Nucleodur C-18 Gravity, 3 µm, 0.4 mL/min, 90-100 % MeCN in 10 min); MS (ESI): m/z calcd for C35H35NO7+ H+: 582.2 [M+H]+, found: 582.5.
(E/Z)-(2-ethoxyvinyl)benzene 204
To KHMDS (0.5 M in toluene, 3.6 mL, 1.83 mmol) in dry DMSO (5 mL) was added dropwise freshly distilled phenylacetaldehyde 202 (200 mg, 1.66 mmol) in DMSO (1 mL) and stirred for 10 min at rt. Et3OBF4 (316 mg, 1.66 mmol) was added whereupon the red colored solution turned yellow. Et2O was added and the solution was washed with water (3x). The solvents were removed under reduced pressure and the residue was purified by FC (petroleum ether/EtOAc 10:1) yielding the enol ethers 204 (140 mg, 57 % in an E/Z ratio of 5:10) as immediately stopped with 1 mL sat NaHCO3. Water was added and the solution was extracted with Et2O. The solvents were removed under reduced pressure and the residue was purified by FC (petroleum ether/EtOAc 10:1) yielding the enol ethers 205 (64 mg, 29 % in an E/Z ratio of 10:3) as yellow liquid.
Rf = 0.6 (petroleum ether/EtOAc 10:1), anisaldehyde; 1H NMR E isomer (400 MHz, CDCl3): [ppm] = 7.49-7.01 (m, 5 H, Ar-H), 6.95 (d, J = 13.0 Hz, 1 H, CH=CH-OMe), 5.72 (d, J = 13.0 Hz, 1 H, CH=CH-OMe), 3.57 (s, 3 H, CH3);
13C NMR E isomer (100 MHz, CDCl3): [ppm] = 149.0 (CH=CH-OMe), 136.5, 128.7, 125.2 (CAr), 105.2 (CH=CH-OMe), 56.6 (CH3); RP HPLC: tr = 3.3 min (EC 125/4 Nucleodur C-18 Gravity, 3 µm, 0.4 mL/min, 80-100 % MeCN in 10 min); MS (ESI): m/z calcd for C9H10O+ H+: 135.0 [M+H]+, found: 135.0.
(E/Z)-2-Amino-N-benzyl-N-benzyloxycarbonyl-3,4-di-O-benzyl-2-deoxy-1,2-O-dimethyl--D -gluco-hex-5-enopyranoside 207
To KHMDS (0.5 M in toluene, 0.38 mL, 0.19 mmol) in dry THF (1 mL) was added dropwise aldehyde 198 (100 mg, 0.17 mmol) in dry THF (1 mL) at –30°C and stirred for 2 h at –30°C. MeOTf (30 µL, 0.27 mmol) was added and stirred for 30 min at –30°C. The reaction was stopped with 1 mL sat NaHCO3. Water was added and the solution was extracted with CH2Cl2 (3x) and dried (MgSO4). The solvents were removed under reduced pressure and the residue was purified by preparative HPLC (Kinetex 5u C18, 250x21.2 mm, 80-100 % MeCN in 20 min) yielding the enol ethers 207 (43 mg, 44 %) as colorless liquid.
Rf = 0.23 (petroleum ether/EtOAc 3:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.29-6.92 (m, 20 H, Ar-H), 5.11-4.95 (m, 2 H, CH2), 4.78-4.44 (m, 6 H, 2x CH2, H-1, H-6), 4.26-4.17 (m, 2 H, CH2), 4.04-3.96 (m, 1 H, H-2), 3.75-3.65 (m, 2 H, H-3, H-4), 3.37, 3.35 (s, 3 H, C=CH-OMe), 2.78 (s ,3 H, OCH3), 2.18, 2.11 (s, 3 H, C(O)CH3);
13C NMR (100 MHz, CDCl3): [ppm] = 128.6-126.2 (CAr, C-5), 102.8, 99.9 (C-6, C-1), 80.4 (C-4), 77.4 (C-2), 74.29 (CBn), 74.0 (CBn), 70.9 (C-3), 67.6 (CBn), 55.6 (C=CHOCH3), 54.8 (OCH3), 47.6 (CBn); RP HPLC: tr = 9.35 min (EC 125/4 Nucleodur C-18 Gravity, 3 µm, 0.4 mL/min, 80-100 % MeCN in 10 min); MS (ESI): m/z calcd for C37H39NO7
+ H+: 610.3 [M+H]+, found: 610.2.
2-O-Benzyl-(2’S,3’S)-methyl-3,4-O-(2’,3’-dimethoxy-butane-2’,3’-diyl)-α-D-mannopyranoside 222[202]
The methylglycoside 222 was synthesized from methyl -D-mannoside in 32 % yield (over four steps) according to Yamasaki et al.[202]
Rf = 0.41, (petroleum ether/EtOAc 1:1) anisaldehyde.
Spectroscopic data according to literature.[202]
2-O-Benzyl-(2’S,3’S)-5-carbaldehyde-methyl-3,4-O-(2’,3’-dimethoxy-butane-2’,3’-diyl)-α-D-mannopyranoside 218A
To a solution of oxalyl chloride (50 µL, 0.58 mmol) in dry CH2Cl2 (2 mL) at –50°C, DMSO (90 µL, 1.25 mmol) dissolved in dry CH2Cl2 (2 mL) was added and the solution was stirred for 15 min at –78°C. A solution of methylglycoside 222 (200 mg, 0.50 mmol) in dry CH2Cl2 (3 mL) was added dropwise and the reaction mixture was stirred 1 h at –78°C. NEt3 (0.35 mL, 2.5 mmol) was added and the solution was allowed to warm to rt. The solvent was removed under reduced pressure and the residue was purified by FC (petroleum ether/EtOAc 2:1) yielding the aldehyde 218A (110 mg, 55 %) as colorless oil.
Rf = 0.35, red smearing (petroleum ether/EtOAc 1:1) anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 9.76
Oxalylchloride (25 μL, 0.29 mmol) was dissolved in dry CH2Cl2 (1 mL) and cooled to -78°C. A solution of DMSO (43 μL, 0.62 mmol) in dry CH2Cl2 (1 mL) was added and the mixture was stirred for 15 minutes at –78°C. A solution of 222 (100 mg, 0.25 mmol) in CH2Cl2 (1.5 mL) was added and the mixture was stirred for 1.5 h at -78°C. Then NEt3 (0.18 mL, 1.25 mmol) was added and the reaction was allowed to warm to rt. The solvent was removed under reduced pressure. MeCN (2 mL), Ac2O (0.26 mL, 3 mmol), K2CO3 (0.16 g, 1.15 mmol) and pyridine (0.4 mL, 5 mmol) were added and the mixture was stirred at 80°C for 20 h. The mixture was filtrated and the filter cake was washed with EtOAc. The solvent was removed under reduced pressure and the remaining residue was purified by FC (petroleum ether/EtOAc 3:1) yielding enol acetate 218 (80 mg, 73 %).
Rf = 0.60 (petroleum ether /EtOAc 3:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.45-7.26 (m, 5 H,
(2S,3S,4aS,6R,7R,8R,8aR)-8-(benzyloxy)-7-hydroxy-2,3-dimethoxy-2,3-dimethyl-5-oxooctahydrobenzo[b][1,4]dioxin-6-yl acetate 219
A solution of enol acetate 218 (50 mg, 0.11 mmol) and mercury sulfate (16.9 mg, 0.1 mmol) in dioxane/5 mM H2SO4 (1 mL/0.5 mL) was stirred for 2 h at 60°C. Brine (1 mL) was added and the mixture was stirred for another
Cyclohexanon derivative 219 (100 mg, 0.23 mmol) was dissolved in dry CH2Cl2 (2 mL). DIPEA (60 µL, 0.53 mmol) and chloromethylmethyl ether (30 µL, 0.53 mmol) were added and the reaction was stirred at rt for 5 d. The mixture was concentrated and the residue was purified by FC (petroleum ether/EtOAc 2:1) yielding
(CAr), 99.9, 99.7 (quart. C), 97.4 (O-CH2-O), 77.1 (C-1), 75.5 (C-2), 74.9 (C-6), 74.3 (CH2), 71.9 (C-1), 71.5 (C-4), µmol) was added and the suspension was stirred for 10 min at 0°C. Keton 223 (40 mg, 80 µmol) dissolved in dry DMSO (1.5 mL) and dry THF (0.5 mL) was added dropwise. After stirring for 1 h at rt water was added and the mixture was extracted with CH2Cl2 (3x) and dried (MgSO4). The solvent was removed under reduced pressure and the residue was purified by preparative HPLC (Kinetex 5u C18, 250x21.2 mm, 40-80 % MeCN in 20 min) yielding the epoxide 224 (10 mg, 28 %) as colorless solid.
Rf = 0.30 (petroleum ether /EtOAc 1:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.44-7.29 (m, 5 H, green color. Unreacted zinc was filtered of using a hollow needle under schlenk technique. The epoxide 224 (246 mg, 0.56 mmol) and cylcohexa-1,4-diene (526 µL, 5.6 mmol) were dissolved in anhydrous, degassed THF (2.0 mL) and CpTiCl solution from above was added slowly and the reaction mixture was stirred for 2 h at rt.
Water was added and the mixture was extracted with CH2Cl2 (3x). After concentration, the residue was dissolved in small amounts of MeCN, filtered and purified by FC (petroleum ether /EtOAc 1:1 to 1:2) yielding the alcohol 226 (186 mg, 75 %) as colorless solid.
Rf = 0.22 (petroleum ether /EtOAc 1:2), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 7.34-7.21 (m, 5 H,
Alcohol 226 (85 mg, 0.19 mmol) was dissolved in dimethoxymethane (5 mL, 56.5 mmol). Phosphorpentoxide (163.2 mg, 1.15 mmol) was added under vigorous stirring and the reaction was stirred at rt for 1 h. The mixture was neutralized with NaHCO3, extracted with EtOAc and dried over MgSO4. The Solvent was removed under reduced pressure and the residue was purified by FC (petroleum ether/EtOAc 2:1) yielding MOM-protected alcohol 227 (62 mg, 61 %) as colorless oil.
(2S,3S,4aR,5R,6R,7S,8S,8aR)-2,3-dimethoxy-6,7-bis(methoxymethoxy)-8-((methoxymethoxy)methyl)-2,3-dimethyloctahydrobenzo[b][1,4]dioxin-5-ol 228
According to GP 9, 60 mg (0.11 mmol) of the benzyl protected cyclohexane derivative 227 was deprotected.
Thus the free alcohol 228 (41 mg, 85 %) was obtained as colorless oil.
Rf = 0.18 (petroleum ether /EtOAc 2:1), anisaldehyde; 1H NMR (400 MHz, CDCl3): [ppm] = 4.79-4.74 (m, 2 H, removed under reduced pressure at rt and the residue was used for the next step without further purification.
The residue was dissolved in dry DMF (2 mL) and sodium azide (58 mg, 900 µmol) was added. The resulting mixture was stirred at 80°C overnight. The suspension was filtered and washed with EtOAc. After removal of the solvent under reduced pressure, the residue was purified by FC (petroleum ether/EtOAc 2:1) yielding azide 229 (8 mg, 19 % over two steps) as a colorless oil.
48.0 (OCH3), 40.2 (C-5), 18.0, 17.9 (CH3); RP HPLC: tr = 6.1 min (EC 125/4 Nucleodur C-18 Gravity, 3 µm, 0.4
Amino-functionalized microtiter plates were treated with a 0.5 % solution of 1,4-phenylene diisothiocyanate (PDC) in DMSO containing 0.4 % EtN(i-Pr)2 for 3 h at room temperature (100 µl per well). Plates were emptied and rinsed twice with isopropanol, twice with water, and twice with sodium carbonate/bicarbonate buffer (100 mM, pH 10.1) to give modified microtiter plates 64 (Scheme 5, chapter 3.1).