تفاعل #495250

معادلة التفاعل

2′-azido-2′-deoxyuridine

2′-azido-2′-deoxyuridine

4,4-dimethoxytrityl chloride

acetic anhydride

→

5′-O-(4,4-dimethoxytrityl)-3′-O-acetyl-2′-azido-2′-deoxyuridine

المردود 90.8%

المذيبات

pyridine

ظروف التفاعل

المعالجة

1. 1
   أخرىprepared
2. 2
   أخرىreaction conditions

الإجراء التجريبي

Starting material was 2′-azido-2′-deoxyuridine prepared according to literature (Verheyden et al., J. Org. Chem. 36:250, 1971), which was 4,4-dimethoxytritylated at 5′-OH with 4,4-dimethoxytrityl chloride in pyridine and acetylated at 3′-OH with acetic anhydride in a one-pot reaction using standard reaction conditions. With 191 mg (0.71 mmole) 2′-azido-2′-deoxyuridine as starting material, 396 mg (0.65 mmol, 90.8%) 5′-O-(4,4-dimethoxytrityl)-3′-O-acetyl-2′-azido-2′-deoxyuridine was obtained after purification via silica gel chromatography. Reduction of the azido group was performed (Barta et al., Tetrahedron 46:587-94, 1990). Yield of 5′-O-(4,4-dimethoxytrityl) 3′-O-acetyl-2′-amino-2′-deoxyuridine after silica gel chromatography was 288 mg (0.49 mmole; 76%). This protected 2′-amino-2′-deoxyuridine derivative (588 mg; 1.0 mmole) was reacted with 2 equivalents (927 mg; 2.0 mmole) N-Fmoc-glycine pentafluorophenyl ester in 10 ml dry DMF overnight at room temperature in the presence of 1.0 mmole (174 μl) N,N-diisopropylethylamine. Solvents were removed by evaporation in vacuo and the residue purified by silica gel chromatography. Yield was 711 mg (0.71 mmole; 82%). Detritylation was achieved by a one hour treatment with 80% aqueous acetic acid at room temperature. The residue was evaporated to dryness, co-evaporated twice with toluene, suspended in 1 ml dry acetonitrile and 5′-phosphorylated with POCl3 and directly transformed in a one-pot reaction to the 5′-triphosphate using 3 ml of a 0.5 M solution (1.5 mmole) tetra(tri-n-butylammonium)pyrophosphate in DMF according to literature. The Fmoc and the 3′-O-acetyl groups were removed by a one-hour treatment with concentrated aqueous ammonia at room temperature and the reaction mixture evaporated and lyophilized. Purification also followed standard procedures by using anion-exchange chromatography on DEAE Sephadex with a linear gradient of triethylammonium bicarbonate (0.1 M-1.0 M). Triphosphate containing fractions, checked by thin layer chromatography on polyethyleneimine cellulose plates, were collected, evaporated and lyophilized. Yield by UV-absorbance of the uracil moiety was 68% or 0.48 mmole.

المصدر