Journal of Organic Chemistry 2003-08-22

Sugar conformational effects on the photochemistry of thymidylyl(3'-5')thymidine.

Tomasz Ostrowski, Jean-Claude Maurizot, Marie-Thérèse Adeline, Jean-Louis Fourrey, Pascale Clivio

Index: J. Org. Chem. 68(17) , 6502-10, (2003)

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Abstract

The synthesis and conformational analysis of 2'-O,5-dimethyluridylyl(3'-5')-2'-O,5-dimethyluridine (1a), the analogue of thymidylyl(3'-5')thymidine (TpT; 1b) in which a methoxy group replaces each 2'-alpha-hydrogen atom, are described. In comparison with TpT, such modification increases the population of the C3'-endo conformer of the sugar ring puckering at the 5'- and 3'-ends from 30 to 75% and from 37 to 66%, respectively. Photolyses of 1a and TpT at 254 nm are qualitatively comparable (the cis-syn cyclobutane pyrimidine dimer and the (6-4) photoproduct are formed), although it is significantly faster in the case of 1a. These results are explained by the increased propensity of the modified dinucleotide to adopt a base-stacked conformation geometry reminiscent of that for TpT.