Uracils, 5-halogeno

As in the case of electrochemical reduction, the photochemical transformation of 5-fluorouracil derivatives differs from that of the other 5-halogeno uracils. The primary photoproduct of 5-fluorouracil, its glycosides and poly(5-FU) is the photohydrate. However, at shorter wavelengths of irradiation, e.g. 254 nm where the photohydrate exhibits absorption, there is elimination of HF from the 5,6 bond and formation of barbituric acid 129 13I>. There is also some evidence for acetone photosensitized formation of cyclobutane dimers of 5-fluorouracil132), as well as dimer formation in irradiated poly(5-FU)133>. 

Treatment of 5-deoxy-5-halogeno nucleosides of adenine and uracil with trimethylamine yielded the corresponding 5-deoxy-5-trimethylammonium salts, whose interaction with anionic polynucleotides was then examined. Various A -alkyl, A -cycloalkyl, and iV-alkaryl derivatives of 3-amino-3-deoxy-and 3, 5 -diamino-3, 5 -dideoxy-adenosine have been prepared from the amino-sugar nucleosides the 3 -benzylamino derivative gave the unusual oxazolidine derivative (52). ° ... 

A convenient synthesis of 5 -deoxy-2-fluoroadenosine from guanosine has been reported. Ring-opening of l-(2,3-anhydro-P-D-lyxofuranosyl)-cytosine and -uracil with ammonium bromide, iodide, azide, and thiocyanate in refluxing ethanol has been used to prepare l-(3-deoxy-3-halogeno-P-D-arabinofuranosyl)-... 

Deoxy-2-halogeno-arabinosyl bromides have been used to prepare halo-nucleosides from 5-substituted-uracil or -cytosine bases leading to 2 -bromo, 2 -chloro, and 2 -fluoro-arabino-nucleoside analogues the 2 -fluoro analogues were most effective as anti-viral 48... 

K.A. Watanabe, T-L. Su, R.S. Klein, C.K. Chu, A. Matsuda, M.W. Chun, C. Lopez, and J.J. Fox, Nucleosides. 123. Synthesis of antiviral nucleosides 5-substituted l-(2-deoxy-2-halogeno-/3-D-arabinofuranosyl)cytosines and -uracils. Some structure-activity relationships. J. Med. Chem. 28 152 (1983). 

Nucleosides. 123. Synthesis of antiviral nucleosides 5-substituted l-(2-deoxy-2-halogeno-p-arabino-furanosyl)cytosines and -uracils. Some structure-activity relationships. J. Med. Chem. 26 152 (1983). 

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