Other Types of Nucleoside Analogue

There has been a further report on altritol nucleic acids (ANA, 258) (see Vol. 33, p. 316), which notes that they are superior to the corresponding DNA, RNA or hexitol nucleic acids (as 258, but lacking the hydroxy groups) in supporting efficient non-enzymatic template-directed synthesis of complementary RNAs from nucleoside 5 -phosphoro-2-methylimidazolides  

3 -0-Thiocarbamoylthymidine has been converted into various species with heterocycles joined to thymidine through an ether link. Water-soluble C-linked nucleoside-porphyrins have been made by reaction of 2, 3 -0-iso-propylideneuridine-5 -carboxaldehyde with pyrrole to give a dipyrromethane, which was treated with p-fluorobenzaldehyde to give after oxidation a porphyrin 

The hydrolysis of the the 3 -thioinosine derivative 280 has been studied over a 

In connection with mechanisms for the alkaline hydrolysis of DNA, the kinetics of hydrolysis of thymidine 3 -phosphodiesters with alcohols such as 2,2,2-trichloroethanol, and also of thymidinyl-(3 -5 )-thymidine, have been studied. With the trifluoroethyl phosphate, the 3, 5 -cyclic phosphate is an intermediate in alkaline hydrolysis, but this was not the case with the dinucleotide. Studies using density functional theory calculations were also reported.  

The hydrolysis of the cyclic phosphorothiolate 281 has been studied between pH —2 and pH 7.6. Below pH 2, the products 282 and 283 were obtained with 283 predominating, whereas between pH 2 and pH 5, the cyclic phosphorothiolate 282 was the main product. Above pH 5, 283 and 284 were obtained, with the latter predominating by 2 1. Mechanisms were discussed, with the uncatalysed reaction to give 282 occurring through attack of water on the methyl group, with C-O bond cleavage.  

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