* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Reference:
[1] Journal of Organic Chemistry, 1985, vol. 50, # 3, p. 406 - 408
2
[ 6979-94-8 ]
[ 2140-67-2 ]
Reference:
[1] Canadian Journal of Chemistry, 2001, vol. 79, # 12, p. 1881 - 1886
3
[ 108-24-7 ]
[ 118-00-3 ]
[ 6979-94-8 ]
Yield
Reaction Conditions
Operation in experiment
98%
With dmap; triethylamine In acetonitrile at 0 - 20℃; for 3 h;
2.2 mL of acetic anhydride (22 mmol) was added dropwise to a suspension of guanosine (2 g, 7.0 mmol) (dried for 2 days over P4O10 in high vacuum), triethylamine (7.7 mL, 55.2 mmol) and N,N-(dimethylamino)pyridine (92 mg, 0.75 mmol) in 27 mL of acetonitrile at 0 °C. The mixture was stirred until it became homogeneous and kept an additional 3 h at room temperature. The reaction was quenched with methanol (2.3 mL). The volume was reduced to 1/3 using a rotary evaporator and diethyl ether was added dropwise to induce precipitation of a fine white powder. The product was collected by filtration, washed with diethyl ether, and then stirred for 2 hr with acetone (30 mL) at 50 °C. The filtrate produced 2.8 g (98percent) of a fine white powder. 1H NMR (200 MHz, DMSO) δ 10.54 (s, 1H, NH) 7.93 (s, 1H, H-8), 6.34 (br, 2H, NH2), 5.98 (d, J = 6.1 Hz, 1H, H-1'), 5.79 (t, J = 5.8 Hz, 1H, H-2'), 5.51-5.48 (m, 1H, H-3'), 4.40-4.37 (m, 1H, H-4'), 4.33-4.31 (m, 1H, H-5'), 4.23-4.28 (m, 1H, H-5), 2.11 (s, 3H, CH3, acetyl), 2.05 (s, 3H, CH3, acetyl), 2.04 (s, 3H, CH3, acetyl); 13C NMR (200 MHz, CDCl3) δ 172.1 (CO), 171.0 (CO), 169.9 (CO), 156.3 (C-6), 152.8 (C-2), 151.2 (C-4), 137.6 (C-8), 119.6 (C-5), 86.1 (C-1'), 82.3 (C-4'), 73.6 (C-2'), 72.3 (C-3'), 61.8 (C-5'), 21.1 (C, acetyl), 20.6 (C, acetyl), 20.2 (C, acetyl); m/z: calcd for C18H21N5O5 (M+H)+: 410.1306, found: 410.1305.
98%
With dmap; triethylamine In acetonitrile at 0 - 20℃; for 1 h;
2.2 mL of acetic anhydride (22 mmol) was added dropwise to a suspension of commercially available guanosine (2 g, 7.0 mmol), triethylamine (7.7 mL, 55.2 mmol) and N,N-(dimethylamino)pyridine (92 mg, 0.75 mmol) in 27 mL of acetonitrile at 0oC. The mixture was stirred until it became homogeneous and kept an additional 1 hr at room temperature. The reaction was quenched with methanol (2.3 mL). The volume was reduced to 1/3 using a rotary evaporator and diethyl ether was added dropwise to induce precipitation of a fine white powder. The product was collected by filtration, washed with diethyl ether, and then stirred for 2 hr with acetone (30 mL) at 50 C. The filtrate produced 2.8 g (98percent) of a fine white powder.
96%
With pyridine In DMF (N,N-dimethyl-formamide) at 75 - 80℃; for 3.75 h;
A suspension of 113 g (0.4 mol) of dry guanosine (6.1), acetic anhydride (240 mL, 2.5 mol), dry pyridine (120 mL) and dry DMF (320 mL) was heated for 3.75 hours at 75°C without allowing the temperature to exceed 80°C. The clear solution was then transferred to a 3L Erlenmyer flask and filled with 2-propanol. Upon cooling the solution to room temperature crystallization was initiated and allowed to proceed at 4°C overnight. The white solid filtrate was filtered, washed with 2-propanol and recrystallized from 2-propanol to give 6.2 (96percent). 1H NMR (300 Mhz, CDCl3) δ 8.20 (s, 1H, H-8), 6.17 (d, J= 5.41 Hz, 1 H, H-1') 5.75 (t, J= 5.39 Hz, 1H, H-2'), 5.56 (t, J = 5.0, H-3'), 4.41 (m, 3H, H-4',5'), 2.14 (s, 3H, Ac), 2.11 (s, 3H, Ac), 2.10 (s, 3H, Ac). 13C NMR (300 MHz, CD3OD) δ 171.0, 170.3, 1702, 157.7, 154.8, 152.4, 136.7, 117.7, 85.5, 80.4, 73.0, 71.3, 64.0, 31.3, 21.2, 21.0.
96%
With dmap; triethylamine In acetonitrile at 20℃; for 0.5 h;
Guanosine 1 (11.3 g, 40 mmol) and N,N-dimethylaminopyridine (366 mg, 3 mmol, 0.07 equiv) were dissolved in 500 mL acetonitrile. After addition of triethylamine (22.9 mL, 158.4 mmol) and Ac2O (13.6 mL, 144 mmol), the mixture was stirred at room temperature for 30 min. The reaction was quenched by addition of 5 mL MeOH and the solvent evaporated in vacuo. The oily residue was recrystallized from 2-propanol to afford 2 as a white powder (15.7 g, 96percent). mp 229-231 oC (lit.[1] mp 228-229 oC); 1H NMR (300 MHz, DMSO-d6): δ 10.75 (1H, br s, OH), 7.94 (1H, s, H-8), 6.55 (2H, br s, NH2), 5.98 (1H, d, J = 6.2 Hz, H-1'), 5.79 (1H, dd, J = 6.0, 6.2 Hz, H-2'), 5.59 (1H, dd, J = 3.9, 6.0 Hz, H-3'), 4.37 (1H, ddd, J = 3.9, 4.9, 5.5 Hz, H-4'), 4.31(1H, dd, J = 4.9, 12.4 Hz, H-5'a), 4.23 (1H, dd, J = 5.5, 12.4 Hz, H-5'b), 2.11 (3H, s, CH3CO), 2.04 (3H, s, CH3CO), 2.03 (3H, s, CH3CO).
80%
With dmap; triethylamine In acetonitrile at 20℃; for 2 h; Cooling with ice
To a stirred suspension of guanosine (5.0 g, 17.7 mmol) in MeCN (65 mL) was added Et3N (6.47 mL, 46.5 mmol) and DMAP (0.22 g, 1.8mmol). The resulting suspension was cooled in an ice bath prior to dropwise addition of Ac2O (5.84 mL, 61.84 mmol). Once the addition was completed, the mixture was allowed to reach room temperature and was stirred for a further 2 h. The reaction was quenched by the addition of MeOH (6.5 mL) and concentrated in vacuo to a white semi-solid precipitate which was boiled with iPrOH and filtered, leaving the product as a white solid. (5.79 g, 80percent). 1H NMR (500 MHz, DMSO-d6): δ (ppm) 10.70 (1H, s, NH); 7.91 (1H, s, H8); 6.49 (2H, s, NH2); 5.98 (1H, d, 3JH1'H2' = 6.1Hz, H1'); 5.79 (1H, t, 3JH2'H3' = 6.0 Hz, H2'); 5.50 (1H, dd, 3JH3'H4' = 4.2, H3'); 4.37 (1H, dd, 3JH5''H4' = 3.8 and 2JH5H5 =11.5 Hz, H5); 4.31 (1H, m, H4); 4.26 (1H, dd, 3JH5H4 = 5.7 Hz, H5'); 2.11 [3H, s, (CH3)3']; 2.04 [3H, s, (CH3)5']; 2.03 [3H, s, (CH3)2']. 13C NMR (125 MHz, DMSOd6): δ (ppm) 170.89 [(CO)5']; 170.24 [(CO)3']; 170.07 [(CO)2']; 157.46 (C6); 154.75 (C2); 151.95 (C4); 136.45 (C8); 117.74 (C5); 85.35 (C1'); 80.40 (C4'); 72.93 (C2'); 71.18 (C3'); 63.92 (C5'); 21.34 [(CH3)5']; 21.20 [(CH3)3'] and 21.01 [(CH3)2'].
79%
With dmap; N,N-dimethyl-ethanamine In acetonitrile at 20℃; for 1 h;
Guanosine (6) 8.40 g (29.7 mmol) and 0.2 g of dimethylaminopyridine were suspended in a mixture of ethyldimethylamine 8.8 g (120 mmol), acetic anhydride 10.2 g (100 mmol) and acetonitrile 100 mL. The reaction mixture was stirred for 60 minutes at room temperature until the solution becomes clear. Methanol was added to the reaction mixture and the solvents were removed under vacuum. The product was recrystallized from isopropanol, washed with acetone and dried to give 6a as pure product. Yield 9.6 g (79percent)
75%
With pyridine In N,N-dimethyl-formamide at 60 - 100℃; for 4 h;
Step A: Preparation of 2',3',5'-Tri-O-acetylguanosine A 12-liter, 3-necked, round bottom flask equipped with a mechanical stirrer, dropping funnel, condenser, and argon inlet is charged with dimethylformamide (9 liters) and guanosine (predried for 20 hours at 80° C. over P4O10, 988 g, 3.50 moles), then heated to 60° C. Pyridine (1.1 liters) followed by acetic anhydride (2.15 liters, 22.8 moles) is added and the mixture heated to 90-100° C. for 4 hours. After cooling to room temperature overnight, the mixture is evaporated to remove approximately 6 liters, then slurried with 10 liters of isopropanol while heating to 70° C. for 1 hour. The mixture is slowly cooled to room temperature, affording the product as a crystalline solid. After collecting by filtration, the solid is washed with isopropanol (2*2 liters), then dried under vacuum at 80° C. for 17 hours to provide the desired intermediate (1,080 g, 75percent).
70%
With pyridine In N,N-dimethyl-formamide at 75℃; for 4.15 h;
Guanosine (1) (90 g, 387.9 mmol) was dissolved in dry pyridine and DMF (95.4 mL) followed by the addition of acetic anhydride (191.15 mL, 2420.0 mmol) and the reaction mixture was stirred at 75 °C for 4.15 h. The resultant clear solution was mixed with 2-propanol and maintained at 4 °C for overnight to afford white solid which was recrystallized from 2-propanol,10percent methanol in chloroform to afforded compound2in 70percent yield.Spectral data is consistent with the literature.
Reference:
[1] Journal of the American Chemical Society, 2005, vol. 127, # 51, p. 18133 - 18142
[2] Synthesis, 1986, # 5, p. 385 - 386
[3] Nucleosides, Nucleotides and Nucleic Acids, 2007, vol. 26, # 6-7, p. 651 - 654
[4] Bioorganic and Medicinal Chemistry, 2012, vol. 20, # 15, p. 4781 - 4789
[5] Bioorganic and Medicinal Chemistry, 2015, vol. 23, # 15, p. 4660 - 4668
[6] Tetrahedron Letters, 2017, vol. 58, # 31, p. 3037 - 3040
[7] Patent: EP1194440, 2005, B1, . Location in patent: Page/Page column 9
[8] European Journal of Medicinal Chemistry, 2012, vol. 53, p. 114 - 123
[9] Tetrahedron Letters, 2005, vol. 46, # 7, p. 1165 - 1167
[10] Chemical Communications, 2012, vol. 48, # 89, p. 11014 - 11016
[11] Journal of Organic Chemistry, 2014, vol. 79, # 8, p. 3311 - 3326
[12] Bioorganic and Medicinal Chemistry, 2008, vol. 16, # 1, p. 19 - 26
[13] Synlett, 2006, # 20, p. 3474 - 3478
[14] Canadian Journal of Chemistry, 1981, vol. 59, # 17, p. 2601 - 2607
[15] Journal of Sulfur Chemistry, 2018, vol. 39, # 1, p. 8 - 22
[16] Angewandte Chemie - International Edition, 2014, vol. 53, # 34, p. 8913 - 8918[17] Angew. Chem., 2014, vol. 126, # 34, p. 9059 - 9064,6
[18] Nucleosides, Nucleotides and Nucleic Acids, 2016, vol. 35, # 2, p. 53 - 63
[19] Bioorganic and Medicinal Chemistry, 2013, vol. 21, # 2, p. 436 - 447
[20] Helvetica Chimica Acta, 1993, vol. 76, # 1, p. 385 - 401
[21] Journal of Labelled Compounds and Radiopharmaceuticals, 1996, vol. 38, # 8, p. 743 - 752
[22] Angewandte Chemie - International Edition, 2015, vol. 54, # 25, p. 7281 - 7284[23] Angew. Chem., 2015, p. 7389 - 7392,4
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[52] ChemBioChem, 2017, vol. 18, # 21, p. 2156 - 2164
4
[ 2466-76-4 ]
[ 118-00-3 ]
[ 6979-94-8 ]
Yield
Reaction Conditions
Operation in experiment
53%
With sodium hydroxide In water at 20℃; for 4 h;
General procedure: Nucleoside/nucleotide (2; 100 mM) and N-acetyl imidazole (1a;10 equiv) were dissolved in water (pH 8; adjusted with 4 MNaOH). The solution was incubated at r.t. for 4 h, and NMR spectra were periodically acquired. The product was purified byreverse-phase (C18) flash coumn chromatography (eluted at pH4 with 100 mM NH4HCO2/MeCN = 98:2 to 80:20). The fractions containing 5 were lyophilised to yield a white powder.
With dmap; triethylamine; In acetonitrile; at 0 - 20℃; for 3h;
2.2 mL of acetic anhydride (22 mmol) was added dropwise to a suspension of guanosine (2 g, 7.0 mmol) (dried for 2 days over P4O10 in high vacuum), triethylamine (7.7 mL, 55.2 mmol) and N,N-(dimethylamino)pyridine (92 mg, 0.75 mmol) in 27 mL of acetonitrile at 0 C. The mixture was stirred until it became homogeneous and kept an additional 3 h at room temperature. The reaction was quenched with methanol (2.3 mL). The volume was reduced to 1/3 using a rotary evaporator and diethyl ether was added dropwise to induce precipitation of a fine white powder. The product was collected by filtration, washed with diethyl ether, and then stirred for 2 hr with acetone (30 mL) at 50 C. The filtrate produced 2.8 g (98%) of a fine white powder. 1H NMR (200 MHz, DMSO) delta 10.54 (s, 1H, NH) 7.93 (s, 1H, H-8), 6.34 (br, 2H, NH2), 5.98 (d, J = 6.1 Hz, 1H, H-1'), 5.79 (t, J = 5.8 Hz, 1H, H-2'), 5.51-5.48 (m, 1H, H-3'), 4.40-4.37 (m, 1H, H-4'), 4.33-4.31 (m, 1H, H-5'), 4.23-4.28 (m, 1H, H-5), 2.11 (s, 3H, CH3, acetyl), 2.05 (s, 3H, CH3, acetyl), 2.04 (s, 3H, CH3, acetyl); 13C NMR (200 MHz, CDCl3) delta 172.1 (CO), 171.0 (CO), 169.9 (CO), 156.3 (C-6), 152.8 (C-2), 151.2 (C-4), 137.6 (C-8), 119.6 (C-5), 86.1 (C-1'), 82.3 (C-4'), 73.6 (C-2'), 72.3 (C-3'), 61.8 (C-5'), 21.1 (C, acetyl), 20.6 (C, acetyl), 20.2 (C, acetyl); m/z: calcd for C18H21N5O5 (M+H)+: 410.1306, found: 410.1305.
98%
With dmap; triethylamine; In acetonitrile; at 0 - 20℃; for 1h;
2.2 mL of acetic anhydride (22 mmol) was added dropwise to a suspension of commercially available guanosine (2 g, 7.0 mmol), triethylamine (7.7 mL, 55.2 mmol) and N,N-(dimethylamino)pyridine (92 mg, 0.75 mmol) in 27 mL of acetonitrile at 0oC. The mixture was stirred until it became homogeneous and kept an additional 1 hr at room temperature. The reaction was quenched with methanol (2.3 mL). The volume was reduced to 1/3 using a rotary evaporator and diethyl ether was added dropwise to induce precipitation of a fine white powder. The product was collected by filtration, washed with diethyl ether, and then stirred for 2 hr with acetone (30 mL) at 50 C. The filtrate produced 2.8 g (98%) of a fine white powder.
96%
With pyridine; In DMF (N,N-dimethyl-formamide); at 75 - 80℃; for 3.75h;
A suspension of 113 g (0.4 mol) of dry guanosine (6.1), acetic anhydride (240 mL, 2.5 mol), dry pyridine (120 mL) and dry DMF (320 mL) was heated for 3.75 hours at 75C without allowing the temperature to exceed 80C. The clear solution was then transferred to a 3L Erlenmyer flask and filled with 2-propanol. Upon cooling the solution to room temperature crystallization was initiated and allowed to proceed at 4C overnight. The white solid filtrate was filtered, washed with 2-propanol and recrystallized from 2-propanol to give 6.2 (96%). 1H NMR (300 Mhz, CDCl3) delta 8.20 (s, 1H, H-8), 6.17 (d, J= 5.41 Hz, 1 H, H-1') 5.75 (t, J= 5.39 Hz, 1H, H-2'), 5.56 (t, J = 5.0, H-3'), 4.41 (m, 3H, H-4',5'), 2.14 (s, 3H, Ac), 2.11 (s, 3H, Ac), 2.10 (s, 3H, Ac). 13C NMR (300 MHz, CD3OD) delta 171.0, 170.3, 1702, 157.7, 154.8, 152.4, 136.7, 117.7, 85.5, 80.4, 73.0, 71.3, 64.0, 31.3, 21.2, 21.0.
96%
With dmap; triethylamine; In acetonitrile; at 20℃; for 0.5h;
Guanosine 1 (11.3 g, 40 mmol) and N,N-dimethylaminopyridine (366 mg, 3 mmol, 0.07 equiv) were dissolved in 500 mL acetonitrile. After addition of triethylamine (22.9 mL, 158.4 mmol) and Ac2O (13.6 mL, 144 mmol), the mixture was stirred at room temperature for 30 min. The reaction was quenched by addition of 5 mL MeOH and the solvent evaporated in vacuo. The oily residue was recrystallized from 2-propanol to afford 2 as a white powder (15.7 g, 96%). mp 229-231 oC (lit.[1] mp 228-229 oC); 1H NMR (300 MHz, DMSO-d6): delta 10.75 (1H, br s, OH), 7.94 (1H, s, H-8), 6.55 (2H, br s, NH2), 5.98 (1H, d, J = 6.2 Hz, H-1'), 5.79 (1H, dd, J = 6.0, 6.2 Hz, H-2'), 5.59 (1H, dd, J = 3.9, 6.0 Hz, H-3'), 4.37 (1H, ddd, J = 3.9, 4.9, 5.5 Hz, H-4'), 4.31(1H, dd, J = 4.9, 12.4 Hz, H-5'a), 4.23 (1H, dd, J = 5.5, 12.4 Hz, H-5'b), 2.11 (3H, s, CH3CO), 2.04 (3H, s, CH3CO), 2.03 (3H, s, CH3CO).
80%
With dmap; triethylamine; In acetonitrile; at 20℃; for 2h;Cooling with ice;
To a stirred suspension of guanosine (5.0 g, 17.7 mmol) in MeCN (65 mL) was added Et3N (6.47 mL, 46.5 mmol) and DMAP (0.22 g, 1.8mmol). The resulting suspension was cooled in an ice bath prior to dropwise addition of Ac2O (5.84 mL, 61.84 mmol). Once the addition was completed, the mixture was allowed to reach room temperature and was stirred for a further 2 h. The reaction was quenched by the addition of MeOH (6.5 mL) and concentrated in vacuo to a white semi-solid precipitate which was boiled with iPrOH and filtered, leaving the product as a white solid. (5.79 g, 80%). 1H NMR (500 MHz, DMSO-d6): delta (ppm) 10.70 (1H, s, NH); 7.91 (1H, s, H8); 6.49 (2H, s, NH2); 5.98 (1H, d, 3JH1'H2' = 6.1Hz, H1'); 5.79 (1H, t, 3JH2'H3' = 6.0 Hz, H2'); 5.50 (1H, dd, 3JH3'H4' = 4.2, H3'); 4.37 (1H, dd, 3JH5''H4' = 3.8 and 2JH5H5 =11.5 Hz, H5); 4.31 (1H, m, H4); 4.26 (1H, dd, 3JH5H4 = 5.7 Hz, H5'); 2.11 [3H, s, (CH3)3']; 2.04 [3H, s, (CH3)5']; 2.03 [3H, s, (CH3)2']. 13C NMR (125 MHz, DMSOd6): delta (ppm) 170.89 [(CO)5']; 170.24 [(CO)3']; 170.07 [(CO)2']; 157.46 (C6); 154.75 (C2); 151.95 (C4); 136.45 (C8); 117.74 (C5); 85.35 (C1'); 80.40 (C4'); 72.93 (C2'); 71.18 (C3'); 63.92 (C5'); 21.34 [(CH3)5']; 21.20 [(CH3)3'] and 21.01 [(CH3)2'].
79%
With dmap; N,N-dimethyl-ethanamine; In acetonitrile; at 20℃; for 1h;
Guanosine (6) 8.40 g (29.7 mmol) and 0.2 g of dimethylaminopyridine were suspended in a mixture of ethyldimethylamine 8.8 g (120 mmol), acetic anhydride 10.2 g (100 mmol) and acetonitrile 100 mL. The reaction mixture was stirred for 60 minutes at room temperature until the solution becomes clear. Methanol was added to the reaction mixture and the solvents were removed under vacuum. The product was recrystallized from isopropanol, washed with acetone and dried to give 6a as pure product. Yield 9.6 g (79%)
77%
A mixture of guanosine 7 (7.5 g, 26.5 mmol), which was dried in vacuo at 100 C for 4days over P2O5, acetic anhydride (15 mL), dry pyridine (7 mL), and dry DMF (30 mL)was heated at 75 C and stirred for 3 h. The clear solution was filtered whilst hot,cooled to room temperature, and evaporated to produce a heavy crystallinesuspension. The residue was treated with 30 mL of 2-propanol and filtered. Theprecipitate was washed with 2-propanol to give a white solid. The residue was treatedwith boiling 2-propanol with vigorous magnetic stirring. The partially dissolvedsuspension was stirred at reflux for 5 min and then was refrigerated at 5 C overnight.The product was filtered, washed with 2-propanol, and dried in vacuo at 80 C, overP2O5, to give 8 as a white powder (8.4 g, 77%).
75%
With pyridine; In N,N-dimethyl-formamide; at 60 - 100℃; for 4h;
Step A: Preparation of 2',3',5'-Tri-O-acetylguanosine A 12-liter, 3-necked, round bottom flask equipped with a mechanical stirrer, dropping funnel, condenser, and argon inlet is charged with dimethylformamide (9 liters) and guanosine (predried for 20 hours at 80 C. over P4O10, 988 g, 3.50 moles), then heated to 60 C. Pyridine (1.1 liters) followed by acetic anhydride (2.15 liters, 22.8 moles) is added and the mixture heated to 90-100 C. for 4 hours. After cooling to room temperature overnight, the mixture is evaporated to remove approximately 6 liters, then slurried with 10 liters of isopropanol while heating to 70 C. for 1 hour. The mixture is slowly cooled to room temperature, affording the product as a crystalline solid. After collecting by filtration, the solid is washed with isopropanol (2*2 liters), then dried under vacuum at 80 C. for 17 hours to provide the desired intermediate (1,080 g, 75%).
70%
With pyridine; In N,N-dimethyl-formamide; at 75℃; for 4.15h;
Guanosine (1) (90 g, 387.9 mmol) was dissolved in dry pyridine and DMF (95.4 mL) followed by the addition of acetic anhydride (191.15 mL, 2420.0 mmol) and the reaction mixture was stirred at 75 C for 4.15 h. The resultant clear solution was mixed with 2-propanol and maintained at 4 C for overnight to afford white solid which was recrystallized from 2-propanol,10% methanol in chloroform to afforded compound2in 70% yield.Spectral data is consistent with the literature.
With pyridine; In DMF (N,N-dimethyl-formamide); at 75℃; for 4h;
The compound of formula (1), guanosine, was converted to the compound of formula [(LA),] (2R, 3R, 4R, [5R)-4-ACETYLOXY-5- (ACETYLOXYMETHYL)-2- (2-AMINO-6-OXOHYDROPURIN-9-] yl) oxolan-3-yl acetate, by the method of Robins et al. (Can J Chem (1981). 59: 2601), as follows. Guanosine was dissolved in dry pyridine and N, [N-DIMETHYLFORMAMIDE] and acetic anhydride was added. The mixture was heated at [75C] for 4 hours, filtered while hot, then the solvent was removed under reduced pressure. The residue was washed with isopropanol and dried to provide crude (2R, 3R, 4R, 5R)-4-acetyloxy-5- (acetyloxymethyl)-2- (2-amino-6- oxohydropurin-9-yl) oxolan-3-yl acetate, which can be used in the next step with no further purification, or purified by recrystallization from isopropanol.
dmap; triethylamine; In acetonitrile; for 2h;
Example 1Synthesis of the compounds according to the inventionFor obtaining the 2' , 3' , 5' -tri-O-acetyl-guanosine (Nucl 1), 2' , 3' , 5' -tri-O-acetyl-inosine (Nucl 7), 2' , 3' , 5' -tri-O-acetyl- adenosine (Nucl 3) and 6-chloro-2' , 3' , 5' -tri-O-acetyl-purine EPO <DP n="28"/>riboside (Nucl 4), the corresponding free nucleoside was used as a starting material (10 mmol guanosine, inosine, adenosine or 6-chloro-purine riboside) and they were reacted in the presence of an acylating agent (40 mmol acetic anhydride) , using acetonitrile as the solvent (125 ml) and catalytic amounts of triethylamine (40 mmol) and dimethylaminopyridine(105 mg) . After 2 hours, the reaction was stopped by adding methanol (15 ml) . The obtained mixture was evaporated in vacuo using a rotary evaporator. The purification step was performed by column chromatography using dichloromethane/methanol as the elution solvent. The structure of the compound was confirmed by nuclear magnetic resonance.
With dmap; triethylamine; In acetonitrile; at 20℃; for 0.5h;
General procedure: Compound 13 (11.0 g, 30.4 mmol) and 4-dimethylaminopyridine (296.9 mg, 2.4 mmol) were dissolved in 100 mL acetonitrile. After slow addition of triethylamine (16.7 mL, 120.0 mmol) and Ac2O (10.0 mL, 106.3 mmol), the mixture continued to stir at room temperature for 30 min. The reaction was quenched by addition of 5 mL MeOH and then the solvent was evaporated in vacuo. The residue was recrystallized from the mixture of 2-propanol and water (v/v, 1:7) to afford 14 as white powder (12.6 g, 85%), mp 192-196 C; 1H NMR (400 MHz, CDCl3): delta 11.70 (1H, s), 6.57 (2H, s), 6.37 (1H, s), 6.02 (1H, d, J = 5.2 Hz), 5.96 (1H, d, J = 3.6 Hz), 4.50 (1H, m), 4.34 (2H, t, J = 6.4 Hz), 2.16 (3H, s), 2.14 (3H, s), 2.03 (3H, s). 13CNMR (100 MHz, CDCl3): delta 170.8, 169.6, 169.5, 157.6, 153.7, 152.3, 121.6, 117.7, 88.4, 79.7, 72.2, 70.4, 62.9, 20.7, 20.6, 20.5.
With N-benzyl-N,N,N-triethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; at 90℃; for 0.166667h;
In an oven-dried flask, peracetylated guanosine 4 [23] (1.56 g, 3.81 mmol), benzyltriethylammonium chloride (1.74 g, 7.64 mmol) and N,N-dimethylaniline (530 muL, 4.18 mmol) were dissolved in dry MeCN (15 mL). POCl3 (1.8 mL, 19.3 mmol) was added and the reaction immersed in a pre-heated oil bath at 90 C for 10 min. All volatiles were flash-evaporated and the blue residue dissolved in chloroform and stirred with crushed ice for 15 min. The organic phase was washed with water (3 * 5 mL), and 5% aq. NaHCO3 solution (3 * 10 mL), and dried over MgSO4. All solvents were removed in vacuo to give 5 as an oil in quantitative yield, which was used in the next step without further purification. 1H NMR (400 MHz, DMSO-d6): delta 7.87 (s, 1H, H-8), 6.01 (d, J = 4.93 Hz, 1H, H-1'), 5.95 (t, J = 5.07, 5.07 Hz, 1H, H-2'), 5.74 (t, J = 4.97, 4.97 Hz, 1H, H-3'), 5.20 (s, 2H, NH2), 4.42 (m, 3H, H-4', H2-5'), 2.15 (s, 3H, OAc), 2.10 (s, 3H, OAc), 2.09 (s, 3H, OAc); 13C NMR (100 MHz, DMSO-d6) ppm 170.5, 169.6, 169.3, 159.1, 153.0, 151.9, 140.7, 125.8, 86.6, 80.0, 72.7, 70.4, 62.9, 20.7, 20.5, 20.4.
82%
Acetonitrile (15 mL) and 1,2-dichloroethane (30 mL) were placed into a 100 mL three-neck round-bottom flask, then the compound 2 (10 g, 24.4 mmol), Et4NCl (11.0 g, 66.4 mmol), N,N-dimethylaniline (4.78 g, 5.0 mL, 35.1 mmol) and phosphoryl chloride (16.8 g, 10.0 mL, 109.6 mmol) were added to the stirred solution. After refluxing for 20-30 min, the solution was added dropwise into the crush ice and stirred vigorously until the ice was dissolved completely. Then the mixture was separated and the aqueous phase was extracted with 1,2-dichloroethane (3 x 50 mL), the combined organic phase was made to PH = 7 by addition of 5% sodium bicarbonate solution, the mixture was separated again and the organic phase was washed with cold water (3 x 60 mL). The organic phase was dried by anhydrous magnesium sulfate (MgSO4). After filtrating and evaporating the solvent, the crude product was recrystallized from ethanol to give 3 as a crystalline solid (8.56 g, 82%), mp 152-153 C (lit.[2] mp 147.5-148.5 oC); 1H NMR (600 MHz, CDCl3): delta 7.89 (1H, s, H-8), 6.01 (1H, d, J = 4.8 Hz, H-1'), 5.94 (1H, dd, J = 4.8, 5.0 Hz, H-2'), 5.74 (1H, dd, J = 4.8, 5.0 Hz, H-3'), 5.29 (2H, br s, NH2), 4.46 (1H, ddd, J = 4.6, 4.8, 5.9 Hz, H-4'), 4.44 (1H, dd, J = 4.6, 13.2 Hz, H-5'a), 4.38 (1H, dd, J = 5.9, 13.2 Hz, H-5'a), 2.15 (3H, s, CH3CO), 2.10 (3H, s, CH3CO), 2.09 (3H, s, CH3CO).
79%
With tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; In acetonitrile; at 20 - 100℃; for 0.166667h;
To a round bottom flask were added compound 8 (8.4 g, 20.5 mmol) and Et4NCl (6.8g, 41 mmol, 2 equiv.), which were both pre-dried in vacuo at 85 C overnight overP2O5, in freshly distilled acetonitrile (20 mL), and the solution was stirred at roomtemperature. Subsequently, distilled N,N-dimethylaniline (2.6 mL, 20.5 mmol, 1 equiv.)and phosphoryl chloride (11.6 mL, 123 mmol, 6 equiv.) were added to the stirredsolution at room temperature. The flask was placed in a preheated hot plate at 100 Cand the solution was heated, whilst stirring at reflux, for 10 min. Volatile materials wereevaporated in vacuo. The resulting yellow foam was dissolved in 100 mL of CHCl3,and stirred vigorously with crushed ice for 15 min. The layers were separated and theaqueous phase was extracted with 5 × 35 mL of CHCl3. The combined organic phasewas kept cold by addition of crushed ice and was washed with 6 × 25 mL of cold water,5% NaHCO3/H2O to pH 7, dried over MgSO4 for 1 h, and filtered. A 60 mL portion of2-propanol was added and the combined filtrate was slowly evaporated in vacuo. Theremaining residue solidified on cooling to room temperature. The residue was filtered,washed with 2-propanol (20 mL) and dried in vacuo overnight. The product wasrecrystallized from 150 mL of boiling 2-propanol yielding 9 as a solid (6.99 g, 79%).
77%
To a 1000 mL flask was added 80 g (0.195 mol) [(2R,3R,4R,5R)-3-4-diacetyloxy-5-(2-amino-6-oxohyropurin-9-yl)oxolan-2-yl]methyl acetate (6.2), tetramethylammonium chloride (44 g, 0.4 mol), anhydrous acetonitrile (400 mL) and N,N-dimethlaniline (25 mL). The flask was placed in an ice salt bath and cooled to 2C. To this solution was added dropwise POCl3 (107 mL 1.15 mol) at a rate that maintained the temperature below 5C (45 minutes). The flask was then removed from the ice bath, outfitted with a condenser, placed in an oil bath and allowed to reflux for 10 minutes whereas the solution changed to a red/brown color. The solvent was then removed under reduced pressure to yield an oily residue which was transferred to a beaker containing 1000 g of ice and 400 mL of CHCl3 and allowed to stir for 1.5 hours to decompose any remaining POCl3. The organic phase was then removed and the aqueous phase extracted with 3 x 50 mL of CHCl3 and pooled with the organic phase. The pooled organic was then back extracted with 50 mL of water followed by stirring with 200 mL of saturated NaHCO3. The organic was further extracted with NaHCO3 until the aqueous extract was neutral (2X). The organic was finally extracted with brine and then dried over MgSO4 for 16 hours. To the solution was added 800 mL of 2-propanol after which the solution was concentrated under reduced pressure. To the oily solid was added 200 mL of 2-propanol and the solution was refrigerated overnight. The crystalline product was filtered, washed, and allowed to dry overnight to give 6.3 (77%). 1H NMR (300 MHz, CD3OD) delta 8.31 (s, 1H, H-8), 7.00 (s, 2H, NH2) 6.06 (d, J= 5.8 Hz, 1H, H-1'), 5.83 (t, J = 6.16 Hz, 1H, H-2'), 5.67 (m, 1H, H-3'), 4.29 (m, 3H, H-4',5'), 2.07 (s, 3H, Ac), 1.99 (s, 3H, Ac), 1.98 (s, 3H, Ac). 13C NMR (300 MHz, CD3OD) delta 171.0,170.4,170.2, 160.8, 154.6, 150.8, 142.2, 124.5, 85.8, 80.6, 72.8, 71.2, 63.9, 21.4, 21.3, 21.1.
64.1%
With tetramethlyammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; In acetonitrile; for 16.75h;Cooling;
In the presence of tetra methyl ammonium chloride, the acetylated purine nucleoside2(100 g, 244.9 mmol) was dissolved in anhydrous acetonitrile (5 mL) and added N,N-Dimethylaniline (31.25 mL, 121.18 mmol) then it was cooled to 2 C. To this solution, POC13(133.7 mL, 1437.0 mmol) was added drop wise maintaining the temperature below 5 C for 45 minutes. The mixture was refluxed for 16 h. The residue was transferred in to ice cold water and extracted with 3 x 50 mL of CHC13.The combined organic phase was washed with saturated NaHCO3followed by brine and dried over MgSO4. To this mixture, 2-propanol was added and evaporated under reduced pressure to get oily residue. The oily residue was again dissolved in 2-propanol and refrigerated overnight followed by filtration and drying under vacuum to affordcompound3in 64.1% yield.
56%
With tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; In acetonitrile; at 45 - 78℃; for 0.5h;
Step B: Preparation of 2-Amino-6-chloro-9-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)purine An 8-liter, 3-neck, round bottom flask equipped with a mechanical stirrer, a condenser, a thermometer, and an argon inlet is charged with dry acetonitrile (2.2 liters) and <strong>[6979-94-8]2',3',5'-tri-O-acetyl-guanosine</strong> (550 g, 1.344 moles). Tetraethylammonium chloride (423 g, 2.55 moles), previously dried for 18 hours over P2O5 at 110 C./high vacuum is added to afford a clear, green solution. After heating to 45-50 C., N,N-dimethylaniline (179 g, 1.48 moles) is added, followed by phosphorus oxychloride (825 g, 5.38 moles) over 15 minutes, during which the temperature rose to 75+-3 C. The mixture was kept at 75+-3 C. for 15 minutes, flash evaporated (TBath<40 C.), and the dark red residue taken up in dichloromethane (4 liters). With vigorous stirring, the mixture is washed with ice water (2.5 L), the organic phase is collected, and the aqueous phase extracted with additional dichloromethane (2*1 L). The combined organic phases are washed with cold water (2*2 liters), saturated aqueous NaHCO3 (2*2 L), dried (Na2SO4), filtered, and concentrated to approximately 1.5 liters. Absolute ethanol (1.5 L) is added and the mixture concentrated to approximately 2 liters. Upon cooling to room temperature, the product crystallizes as a colorless solid (321 g, 56%) after drying in vacuo at 40 C. for 17 hours.
Ca. 55%
With tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; at 100℃;
Compound <strong>[6979-94-8](2R,3R,4R,5R)-2-(acetoxymethyl)-5-(2-amino-6-oxo-1H-purin-9(6H)-yl)tetrahydrofuran-3,4-diyl diacetate</strong> (6a) 5.5 g (13.4 mmol) and 1.88 g (11.8 mmol) of tetraethylammonium chloride were dried at 140 C for several hours. After that, a mixture of 1.41 g (11.8 mmol) of dimethylaniline and 10.96 g (70.8 mmol) of phosphorus oxychloride were added. The reaction mixture was heated to 100 C for 15-30 min. till the solution becomes clear and colored orange indicating the completion of the reaction. The excess phosphorus oxychloride was removed under reduced pressure and the residue was suspended in an ice while stirring. The product was extracted with 100 mL dichloromethane three times and the organic phase was collected, washed with 100 mL 1N HCl three times followed by washing two times with 100 mL water and one time with 100 mL saturated NaCl solution. The organic layer was dried over sodium sulfate and the dichloromethane was evaporated under vacuum to produce the pure compound 6b as yellowish foam in about 55% yield
With tetraethylammonium chloride; trichlorophosphate;N,N-dimethyl-aniline; In acetonitrile; at 20℃; for 0.166667h;Heating / reflux;
The compound of formula [(LA)] was converted to the compound of formula [(LB),] (2R, 3R, 4R, [5R)-4-ACETYLOXY-5- (ACETYLOXYMETHYL)-2- (2-AMINO-6-CHLOROPURIN-9-YL) OXOLAN-3-YL] acetate following the method of Robins et al. (Can J Chem (1981). 59: 2601), as follows. To a mixture of (2R, 3R, 4R, [5R)-4-ACETYLOXY-5- (ACETYLOXYMETHYL)-2- (2-AMINO-6-] oxohydropurin-9-yl) oxolan-3-yl acetate and tetraethylammonium chloride in acetonitrile was added N, N-dimethylaniline and phosphoryl chloride at room temperature. The mixture was heated at reflux for 10 minutes, then solvent removed under reduced pressure. The residue was dissolved in chloroform, stirred with ice, then washed with water, sodium bicarbonate solution, water, dried over magnesium sulfate, and filtered. Isopropanol was added to the filtrate, which was reduced in volume under reduced pressure. The crystalline product that separated was filtered off, washed with isopropanol, and dried under reduced pressure, to provide (2R, 3R, 4R, [5R)-4-ACETYLOXY-5- (ACETYLOXYMETHYL)-2- (2-AMINO-6-CHLOROPURIN-9-YL) OXOLAN-3-YL] acetate.
With tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; In acetonitrile; for 2h;Heating / reflux;
EXAMPLE 1; Preparation of a Compound of Formula (2); To a solution of 2',3',5'-triacetylguanosine (4.0 g, 9.78 mmol) and tetraethylammonium chloride (4.9 g, 29.3 mmol) in acetonitrile (60 ml) was added N,N-dimethylaniline (1.85 ml, 14.67 mmol), followed by phosphorus oxychloride (7.28 ml, 78 mmol). The resulting solution was refluxed for 2 hours, after which the solvent was removed under reduced pressure. The residue was diluted with methylene chloride, washed with aqueous saturated sodium bicarbonate, and the organic layer dried over sodium sulfate. The solvent was removed under reduced pressure, and the residue chromatographed on silice gel, eluting with 4% methanol/methylene chloride, to provide (2R,3R,4R,5R)-4-acetyloxy-5-(acetyloxymethyl)-2-(2-amino-6-chloropurin-9-yl)oxolan-3-yl acetate, the compound of formula (2). 1H NMR (CDCl3) was satisfactory.
With tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate; In 1,2-dichloro-ethane; acetonitrile; for 0.5h;Reflux;
Acetonitrile (20 mL) and 1, 2-dichloroethane (40 mL) were placed into a 100 mL round-bottom flask, then the compound 14 (10.0 g, 20.5 mmol), Et4NCl (6.2 g, 41.0 mmol), N,N-dimethylaniline (5.2 mL, 41.0 mmol) and phosphoryl chloride (7.5 mL, 81.9 mmol) were added slowly to the solution. After refluxing for 30 min, the reaction solution was added drop wise into the crush ice and stirred vigorously until the ice was dissolved completely. Then the mixture was separated and the aqueous phase was extracted with 1, 2-dichloroethane (3 x 50 mL). The combined organic phase was neutralized with 5% sodium bicarbonate solution and dried by MgSO4. After filtrating and evaporating the solvent, the crude product was recrystallized from ethanol to give 15 as crystalline solid (7.4 g, 71%), mp 138-140 C; 1H NMR (400 MHz, CDCl3): delta 6.26 (1H, m), 6.05 (1H, d, J = 4.0 Hz), 6.00 (1H, t, J = 6.0 Hz), 5.57 (2H, s), 4.48 (1H, m), 4.41 (1H, m), 4.33 (1H, m), 2.15 (3H, s), 2.14 (3H, s), 2.00 (3H, s). 13C NMR (100 MHz, CDCl3): delta 170.7, 169.6, 169.5, 158.9, 153.4, 150.4, 139.6, 123.8, 87.3, 79.6, 72.0, 70.2, 62.6, 20.6, 20.5, 20.47.
With 1,3-dibromo-5,5-dimethylimidazolidine-2,4-dione In acetonitrile at 25℃; for 4h;
Typical procedure for the bromination of unprotected nucleosides: DBH (323 mg, 1.13 mmol) was added to a stirred solution of 1d (500 mg, 2.05 mmol) in DMF (5 mL). The resulting pale-yellow solution was stirred at room temperature for 20 minutes or until TLC showed absence of starting material and formation of less polar product. Volatiles were evaporated and the residue was coevaporated with MeCN. The resulting pale solid was crystallized from hot acetone to give 2d (500 mg, 75%) as colorless crystals with data as reported.14
84%
With bromine In water at 20℃;
Syntheses of 8-bromo-2',3',5'-tri-O-acetyl-guanosine (2)
Compound 1 (5.77mg, 14.1mmol) was suspended in distilled water (34 mL). Saturated bromine water (ca. 20 mL) was added with vigorous stirring at room temperature at such a rate that the orange colour dissipated between additions. Once the orange color persisted, the mixture was allowed to stir for a further 30 min before filtering. The solution was filtered and the solid washed with ice cold iPrOH leaving the product as a pale orange solid. (5.79 g, 84%). 1H NMR (500 MHz, DMSO-d6): δ (ppm) 10.86 (1H, s, NH); 6.55 (2H, s, NH2); 6.03 (1H, dd, 3JH2'H1' = 4.5 and 3JH2'H3' = 6.4 Hz, H2'); 5.88 (1H, d, H1'); 5.65 (1H, t, 3JH3'H4' = 6.3, H3'); 4.42 (1H, dd, 3JH5'H4' = 3.8 and 2JH5'H5'' = 11.9 Hz, H5'); 4.32 (1H, td, 3JH4'H5'' = 6.1, H4'); 4.21 (1H, dd, H5''); 2.11 [3H, s, (CH3)3']; 2.07 [3H, s, (CH3)2']; 1.99 [3H, s, (CH3)5']. 13C NMR (125MHz, DMSO-d6): δ (ppm) 171.02 [(CO)5']; 170.40 [(CO)3']; 170.33[(CO)2']; 156.33 (C6); 154.73 (C2); 152.84 (C4); 121.03 (C8); 118.11 (C5); 88.55 (C1'); 80.23 (C4'); 72.19 (C2'); 70.84 (C3'); 63.69 (C5'); 21.41 [(CH3)5']; 21.23 [(CH3)3'] and 21.17 [(CH3)2'].
With Etamon chloride; <i>N</i>,<i>N</i>-dimethyl-aniline; trichlorophosphate In 1,2-dichloro-ethane; acetonitrile at 20℃; Reflux;
2 Example 2: Preparation of 2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl) purine (3)
Anhydrous acetonitrile (15 mL) and anhydrous 1,2-dichloroethane (30 mL) were placed into a 100 ml three-necked bottle. While stirring at room temperature, 10.0 g (24.4 mmol) compound 2, 11.0 g (66.4 mmol) Et4NCl and 16.8 g (10.0 mL, 109.6 mmol) POCl3, and 4.78 g (5.0 mL, 35.1 mmol) N,N-dimethylaniline were successively added therein, and rapidly heated to reflux. After holding 20-25 min, the resultant mixed solution was slowly and dropwise added to brash ice and stirred, and 10 mL 1,2-dichloroethane was supplemented. After brash ice was completely dissolved, the resultant mixed solution was poured into a 250 mL separating funnel for separation. After the aqueous phase was extracted three times with 50 mL 1,2-dichloroethane, the organic phases were combined together and adjusted to a pH of 7 with cold 5% sodium carbonate solution, then a liquid separation was carried out. The organic phase was washed three times with 50 mL cold water, and dried over anhydrous MgSO4, filtered and evaporated under reduced pressure to remove the solvent, and then 70 mL anhydrous ethanol was added to the residue which was recrystallized therefrom as a white crystal 3 (8.56 g, with a yield of 81.9%), m.p 155-156 °C; 1H NMR (600 MHz, CDCl3) δ 7.88 (1H, s), 5.99 (1H, d, J = 4.8 Hz), 5.93 (1H, t, J = 4.9 Hz), 5.72 (1H, t, J = 4.9 Hz), 5.27 (2H, br s), 4.35-4.44 (3H, m), 2.13 (3H, s), 2.09 (3H, s), 2.07 (3H, s).
81.9%
With Etamon chloride; <i>N</i>,<i>N</i>-dimethyl-aniline; trichlorophosphate In 1,2-dichloro-ethane; acetonitrile Reflux;
2 EXAMPLE 2 Preparation of 2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (3)
EXAMPLE 2 Preparation of 2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (3) Anhydrous acetonitrile (15 mL) and anhydrous 1,2-dichloroethane (30 mL) were placed into a 100 ml three-necked bottle. While stirring at room temperature, 10.0 g (24.4 mmol) compound 2, 11.0 g (66.4 mmol) Et4NCl and 16.8 g (10.0 mL, 109.6 mmol) POCl3, and 4.78 g (5.0 mL, 35.1 mmol) N,N-dimethylaniline were successively added therein, and rapidly heated to reflux. After holding 20-25 min, the resultant mixed solution was slowly and dropwise added to brash ice and stirred, and 10 mL 1,2-dichloroethane was supplemented. After brash ice was completely dissolved, the resultant mixed solution was poured into a 250 mL separating funnel for separation. After the aqueous phase was extracted three times with 50 mL 1,2-dichloroethane, the organic phases were combined together and adjusted to a pH of 7 with cold 5% sodium carbonate solution, then a liquid separation was carried out. The organic phase was washed three times with 50 mL cold water, and dried over anhydrous MgSO4, filtered and evaporated under reduced pressure to remove the solvent, and then 70 mL anhydrous ethanol was added to the residue which was recrystallized therefrom as a white crystal 3 (8.56 g, with a yield of 81.9%), m.p 155-156° C.; 1H NMR (600 MHz, CDCl3) δ 7.88 (1H, s), 5.99 (1H, d, J=4.8 Hz), 5.93 (1H, t, J=4.9 Hz), 5.72 (1H, t, J=4.9 Hz), 5.27 (2H, br s), 4.35-4.44 (3H, m), 2.13 (3H, s), 2.09 (3H, s), 2.07 (3H, s).
80%
With 4-dimethylaminopyridine; anhydrous tetramethylammonium chloride; trichlorophosphate In acetonitrile Reflux;
2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine(3)
2',3',5'-O-triacetyl-guanosine (2) (81.88 g, 0.20 mol) and tetramethylammonium chloride (43.84 g, 0.40 mol) were suspended in250 ml of dry acetonitrile. Dimethylaniline (25.4 ml, 0.20 mol) and phosphorus oxychloride (110 ml, 1.17 mol) were added and the reaction mixture was boiled under reflux until the precipitate was almost completely dissolved (nearly 20 min). The mixture was concentrated to a minimal volume, the residue was dissolved in chloroform (700 ml),stirred with crushed ice and shaken until the precipitate was completely dissolved. The aqueous phase was washed twice with chloroform. Thecombined organic phase was washed twice with cold water, then with 5%NaHCO3 up to pH 8-9, and with cold water until neutral reaction. The solution was concentrated up to oil, isopropanol (50 ml) was added, the solution was evaporated until crystals forming and cooled. The precipitate was filtered off and washed with cold isopropanol and hexane.The final product was purified by flash chromatography (35 g of silica,elution by 50 ml of chloroform), eluate was evaporated and the residuewas crystallized from 450 ml of isopropanol. Yield was 68 mg (0.16 mol,80%) purity 100% (Rt = 10.690 min), m.p. 153-155 °C. M/z:428.1009/430.0952 [M+H]+ (calc. 428.0968/430.0952 [M+H]+ 35/37Cl).1H NMR (700 MHz, DMSO-d6, J, Hz, 30 C): 1H NMR (700 MHz,DMSO-d6, J, Hz, 30 C): 8.36 (s, 1 H, H8), 7.04 (s, 2 H, NH2), 6.11 (d, J= 5.8, 1 H, H1’), 5.80 (dd, J = 5.8; 5.8, 1 H, H2’), 5.55 (dd, J = 5.8; 5.7, 1H, H3’), 4.41 (dd, J = 11.7; 3.9, 1 H, H5’a), 4.37 (m, 1 H, H4’), 4.29 (dd, J= 11.9; 5.9, 1 H, H5’b), 2.13 (s, 3 H, CH3CO), 2.05 and 2.04 ppm (2 s, 6H, 2 CH3CO).
With dmap; triethylamine In acetonitrile at 20℃; for 0.5h;
1 Example 1: Preparation of 2-amino-6-hydroxyl-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (2)
;At room temperature, dried guanosine 1 (11.3 g, 40 mmol), triethylamine (22.9 mL, 158.4 mmol) and acetic anhydride (13.6 mL, 144 mmol) were respectively dissolved in 500 ml anhydrous acetonitrile, and 4-dimethylamino pyridine (366 mg, 3 mmol) was added therein. The resultant mixed solution was sharply stirred at room temperature for 30 min, and then continuously stirred for 10 min after 5 ml anhydrous methanol was added. The solvent was evaporated under reduced pressure, and the resultant solid was recrystallized with 180 mL isopropanol to obtain white crystals 2 (15.7 g, 96%), m.p 229-231 °C; 1H NMR (300 MHz, DMSO-d6) δ 10.75 (1H, br s),7.94 (1H, s), 6.55 (2H, br s), 5.98 (1H, d, J = 4.8 Hz), 5.79 (1H, t, J = 5.5 Hz), 5.59 (1H, t, J = 5.5 Hz), 4.40-4.24 (3H, m), 2.11 (3H, s), 2.04 (3H, s), 2.03 (3H, s).
96%
With dmap; triethylamine In acetonitrile at 20℃; for 0.666667h;
1 EXAMPLE 1 Preparation of 2-amino-6-hydroxyl-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (2)
EXAMPLE 1 Preparation of 2-amino-6-hydroxyl-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine (2) At room temperature, dried guanosine 1 (11.3 g, 40 mmol), triethylamine (22.9 mL, 158.4 mmol) and acetic anhydride (13.6 mL, 144 mmol) were respectively dissolved in 500 ml anhydrous acetonitrile, and 4-dimethylamino pyridine (366 mg, 3 mmol) was added therein. The resultant mixed solution was sharply stirred at room temperature for 30 min, and then continuously stirred for 10 min after 5 ml anhydrous methanol was added. The solvent was evaporated under reduced pressure, and the resultant solid was recrystallized with 180 mL isopropanol to obtain white crystals 2 (15.7 g, 96%), m.p 229-231° C.; 1H NMR (300 MHz, DMSO-d6) δ 10.75 (1H, br s),7.94 (1H, s), 6.55 (2H, br s), 5.98 (1H, d, J=4.8 Hz), 5.79 (1H, t, J=5.5 Hz), 5.59 (1H, t, J=5.5 Hz), 4.40-4.24 (3H, m), 2.11 (3H, s), 2.04 (3H, s), 2.03 (3H, s).
General Nucleoside Acetylation Protocol
General procedure: Nucleoside/nucleotide (2; 100 mM) and N-acetyl imidazole (1a;10 equiv) were dissolved in water (pH 8; adjusted with 4 MNaOH). The solution was incubated at r.t. for 4 h, and NMR spectra were periodically acquired. The product was purified byreverse-phase (C18) flash coumn chromatography (eluted at pH4 with 100 mM NH4HCO2/MeCN = 98:2 to 80:20). The fractions containing 5 were lyophilised to yield a white powder.