High yield protection of purine ribonucleosides for phosphoramidite RNA synthesis

Tetrahedron Letters

Volumn 40, Issue 22, 1999, Pages 4153-4156

  Song, Quanlai ^a   Wang, Weimin ^a   Fischer, Artur ^a   Zhang, Xiaohu ^a   Gaffney, Barbara L ^a   Jones, Roger A ^a  

^a RUTGERS UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

NEBULARINE; PHOSPHONIC ACID DERIVATIVE; PHOSPHORAMIDOUS ACID DERIVATIVE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL MODIFICATION; RNA SYNTHESIS;

EID: 0033612261     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)00733-9     Document Type: Article

References (12)

1. Zhang, X.; Abad, J.-L.; Huang, Q.; Zeng, F.; Gaffney, B. L.; Jones, R. A. Tetrahedron Lett. 1997, 38, 7135-7138.
2. 12 was prepared by adding 38.3 mL of diphenyl phosphite (0.20 mol) over 10 min to 400 mL of 7.4 M aq ammonia. This mixture was stirred for 1 h and then concentrated. The residue was coevaporated with absolute ethanol (2 x 100 mL) and triturated with ethyl ether (400 mL) for 30 minutes. The product was isolated as 29.9 g of a colorless crystalline solid (0.17 mol, 85%). A portion of ammonium phenyl-H-phosphonate (2.63 g, 15 mmol) was converted to the DBU (1,8- diazabicyclo[5.4.0]undec-7-ene) salt by addition of DBU (2.3 mL, 15 mmol) and co-evaporation with pyridine (50 mL).The residue was dissolved in anhydrous pyridine (100 mL), and 4 (3.52 g, 5 mmol) was added, followed by BDMS-C1 (tert-butyldimethylsilyl chloride) (2.26 g, 15 mmol) and DBU (3.8 mL, 25 mmol). The mixture was stirred for 48 h and then poured into aq potassium phosphate (100 mL, 0.5 M, pH 7.0) and extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried and concentrated. To a mixture of the residue and glycerol (1.38 g, 15 mmol), first dried by co-evaporation with pyridine (50 mL) and dissolved in dry pyridine (50 mL), was added 1-adamantanecarbonyl chloride (2.98 g, 15 mmol). After stirring 10 min, the solution was poured into aq potassium phosphate (100 mL) and extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried and concentrated. The residue was purified by chromatography on silica gel using petroleum ether:ethyl acetate (3:2) to give 2.65 g of 12a (3.24 mmol, 65% from 4, 59% from 1).
3. Synthesis of 12b: To guanosine (5.66 g, 20 mmol) dried by co-evaporation with pyridine (2 x 100 mL) and suspended in anhydrous pyridine (200 mL) was added over 5 min trimethylchlorosilane (15.2 mL, 120 mmol). This solution was stirred for 1 h. The acylating reagent was prepared by co-evaporating 1-hydroxybenzotriazole (5.40 g, 40 mmol) and N-methylmorpholine (4.40 mL, 40 mmol) with dry acetonitrile (2 x 50 mL), dissolving the mixture in dichloromethane (100 mL), adding phenoxyacetyl chloride (5.53 mL, 40 mmol) to it, and shaking the mixture for 10 min. This reagent was then added to the nucleoside solution. After 36 h, water (50 mL) was added, the mixture was concentrated, and the residue was co-evaporated with water (2 x 50 mL). The crystalline solid that formed during concentration was shaken with water (50 mL), filtered and washed with water (20 mL) and 2-propanol (3 x 20 mL) to give 7.90 g of 6 as a colorless solid (18.9 mmol, 95%). To a portion of 6 (4.17 g, 10 mmol) dissolved in anhydrous pyridine (50 mL) was added dimethylformamide dimethyl acetal (1.59 mL, 11.6 mmol). After 1 h, the solution was concentrated to a gum. To the residue dissolved in dry pyridine (50 mL) was added dimethoxytrityl chloride (4.07 g, 12 mmol). The mixture was stirred for 2 h and then poured into aq potassium phosphate (100 mL, 0.5 M, pH 7.0). The mixture was extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried and concentrated. The residue was dissolved in dichloromethane (10 mL) and precipitated by addition to diethyl ether. Filtration of the precipitate gave 7.3 g of crude 8 (est. 94% pure). To 3.7 g of crude 8 dissolved in anhydrous pyridine (100 mL) was added ammonium phenyl-H-phosphonate (2.63 g, 15 mmol), prepared as above, and DBU (2.3 mL, 15 mmol), that had been co-evaporated with pyridine (50 mL), followed by BDMS chloride (2.26 g, 15 mmol) and DBU (3.8 mL, 25 mmol). The mixture was stirred for 48 h and then poured into aq potassium phosphate (100 mL, 0.5 M, pH 7.0) and extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried and concentrated. To the residue and glycerol (1.38 g, 15 mmol), dried by co-evaporation with pyridine (50 mL) and dissolved in dry pyridine (50 mL), was added 1 - adamantanecarbonyl chloride (2.98g, 15 mmol). After 10 min of stirring, the solution was poured into aq potassium phosphate (100 mL) and extracted with dichloromethane (2 x 100 mL). The combined organic layers were dried and concentrated. The residue was purified by chromatography on silica gel using acetone:dichloromethane (5:95 to 15:85), to give 2.63 g of 12b (3.15 mmol, 63% from 5).
4. Wu, T.; Ogilvie, K. K.; Pon, R. T. Tetrahedron Lett. 1988, 29, 4249-4252.
5. Chaix, C.; Duplaa, A. M.; Molko, D.; Téoule, R. Nucleic Acids Res. 1989, 17, 7381-7393.
6. Singh, K. K.; Nahar, P. Synthetic Communications 1995, 25, 1997-2003.
7. Sinha, N. D.; Davis, P.; Schultze, L. M.; Upadhya, K. Tetrahedron Lett. 1995, 36, 9277-9280.
8. Gryaznov, S. M.; Letsinger, R. L. J. Am. Chem. Soc. 1991, 113, 5876-5877.
9. Gryaznov, S. M.; Letsinger, R. L. Nucleic Acids Res. 1992, 20, 1879-1882.
10. Hayakawa, Y.; Kataoka, M. J. Am. Chem. Soc. 1998, 120, 12395-12401.
11. Zemlicka, J. Collect. Czech. Chem. Commun. 1963, 28, 1060-1062.
12. Ozola, V.; Reese, C. B.; Song, Q. Tetrahedron Lett. 1996, 37, 8621-8624.