Reaktion #49785

Reaktionsgleichung

2-Amino-6-methoxy-9-b-D-arabinofuranosyl-9H-purine

2,2,2-trichloroethanol

Trichloroethyl acetate

Acetyl chloride

trichloroethyl acetate

trichloroethyl propionate

→

desired product

2-Amino-6-methoxy-9-(5-O-acetyl-β-D -arabinofuranosyl)-9H-purine

Lösungsmittel

H2O

pyridine

potassium phosphate

pyridine

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewas synthesized
2. 2
   Sonstigeequipped with argon inlet valve
3. 3
   workup.ADDITIONadded over a ten minute period
4. 4
   Sonstigethe temperature below 25° C.
5. 5
   WaschenThe resulting product was washed with H2O (2×100 mL), 5% NaHCO3 (2×100 mL), and H2O (2×100 mL)
6. 6
   TrocknenThe organic layer was dried over MgSO4
7. 7
   Filtrationfiltered through Whatman #1 paper
8. 8
   workup.DISTILLATIONdistilled under vacuum
9. 9
   workup.ADDITIONwere added to the reaction
10. 10
    workup.STIRRINGAfter stirring at 40° for an additional 24 hours the reaction
11. 11
    Sonstigewas quenched
12. 12
    Filtrationby filtering off the enzyme
13. 13
    Sonstigethe solvent was removed in vacuo
14. 14
    SonstigeThe crude product was purified by chromatography on a 4.5×25 cm silica gel column with CH2Cl2 :CH3OH (9:1) as eluant

Vorschrift

2-Amino-6-methoxy-9-b-D-arabinofuranosyl-9H-purine (1.0 g, 3.3 mmol) was suspended in 40 ml of pyridine that contained 300 μL of H2O and 1 ml of trichloroethyl propionate (Trichloroethyl acetate was synthesized as follows:2,2,2-trichloroethanol (19.1 mL, 197.1 mmole) and dry pyridine (40 mL) were placed in a three-neck, round-bottom flask equipped with argon inlet valve, thermometer, dropping funnel, magnetic stirring, and ice/H2O bath. Acetyl chloride (14.5 mL, 199.8 mmole) was placed in the dropping funnel and added over a ten minute period, keeping the temperature below 25° C. while stirring under argon. The resulting product was washed with H2O (2×100 mL), 5% NaHCO3 (2×100 mL), and H2O (2×100 mL). The organic layer was dried over MgSO4, then filtered through Whatman #1 paper, and distilled under vacuum. A middle cut of 5.18 g was the desired material, contaminated with a small amount of acetic acid: 1H-NMR (CDCl3): δ4.73 (s, 2H, CH2O), 2.20 (s, 3H, CH3CO); MS (Cl, CH4): m/z 197 (M+H, C4H5O237Cl3), 195 (M+H, C4H5O237Cl235Cl), 193 (M+H, C4H5O2O35Cl237Cl), 191 (M+H, C4H5O235Cl3), 159 (195-HCl, C4H4O237Cl2), 157 (193-HCl, C4H4O237Cl35Cl), 155 (191-HCl, C4H4O235Cl2); (El): m/z 195 (M+H), 193 (M+H), 191 (M+H), 157 (193-HCl), 155 (191-HCl). Analysis for C4H5Cl3O2 +0.054 mole CH3COOH: C, 25.35; H, 2.70; CI, 54.62. Found: C, 25.57; H, 2.72; Cl, 54.66.). The reaction was initiated with 0.050 g of subtilisin (Sigma Chemical Co., St. Louis, Mo., P-5380, lot#38F-0356,), which had been activated by dissolving 1 g of the enzyme in 20 ml of 0.1M potassium phosphate at pH 7.8 and lyophilizing to dryness. After stirring for 23 hours at 40° C. an additional 50 mg of subtilisin and 2 mL of trichloroethyl acetate were added to the reaction. After stirring at 40° for an additional 24 hours the reaction was quenched by filtering off the enzyme and the solvent was removed in vacuo. The crude product was purified by chromatography on a 4.5×25 cm silica gel column with CH2Cl2 :CH3OH (9:1) as eluant. Product fractions were pooled and lyophilized from water to yield 0.28 g of the desired product as a white powder. TLC Rf =0.35 (silica gel; CH2Cl2 :CH3OH (9:1)); UV λmax (ε, mM-1 cm-1) at pH 7.0, 279 nm (8.8). 1H-NMR(200 MHz, DMSO-d6): δ7.83 (s, 1H, H8), 6.45 (s, 2H, 2-NH2), 6.14(d, 1H, J=3.7 Hz, H1'), 5.75 (d, 1H, J=4.5 Hz, 2'--OH), 5.65 (d, 1H, J=3.7 Hz, 3'--OH), 4.26(m, 2H, H2' and H3'), 4.07 (m, 2H, H5') 3.94 (s, 3H, --OCH3) 3.92 (m, 1H, H4'), 2.01 (s, 3H, CH3CO2--); MS (Cl) 340 (M+1), 280 (M--CH3CO2). Anal. Calcd. for C14H19N5O6.0.52 H2O: Calcd: C, 44.77; H, 5.22; N, 20.12. Found: C, 44.79; H, 5.21; N, 20.09.

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