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ChemicalBook CAS DataBase List Thymidine
50-89-5

Thymidine synthesis

10synthesis methods
-

Yield:50-89-5 97%

Reaction Conditions:

with β-naphthol in dichloromethane; for 0.166667 h;Product distribution / selectivity;Irradiation with mercury arc lamp;

Steps:

1

A solution containing 5'-O-dimethoxytrityl thymidine (1 mM) and 2-naphthol (10 mM) in methylene chloride was placed in a quartz cuvette having a 2 mm path length and exposed to light from a 200 W high-pressure mercury arc lamp for 10 minutes. The light was passed through bandpass and sharpcut filters to give maximum transmission at 360 nm wavelength with a cutoff at 320 nm. The irradiated solution was analyzed by high performance liquid chromatography (HPLC) and compared with a non-irradiated solution stored in the dark for the same period of time. The analyses showed essentially complete (97%) detritylation of the exposed nucleoside to give thymidine and no detritylation of the non-exposed sample. 2-Naphthol is known to be substantially more acidic in the excited state (SI, pK=3.1) than in the ground state (So, pK=9.5) (Calvert and Pitts, 1966). The efficiency of this reaction is somewhat surprising in view of the short lifetime of the S1 excited state (10 nanoseconds) and the fact that the triplet (T1) state is not acidic (pK8). A similar experiment was performed using 4-nitrophenol (So, pK=7.15) instead of 2-naphthol. 4-nitrophenol absorbs strongly at longer wavelengths than does 2-naphthol and was exposed using filters for 365 nm maximum transmission with a 345 nm cutoff. Although detritylation of 5'-O-dimethoxytrityl thymidine in the exposed solution proceeded more slowly with this phenol, it continued in the dark for several minutes after the exposure, indicating the formation of a long-lived acidic species.

References:

US2010/10209,2010,A1 Location in patent:Page/Page column 8

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