<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Manetto, Antonio</style></author><author><style face="normal" font="default" size="100%">Georganakis, Dimitris</style></author><author><style face="normal" font="default" size="100%">Leondiadis, Leondios</style></author><author><style face="normal" font="default" size="100%">Gimisis, Thanasis</style></author><author><style face="normal" font="default" size="100%">Mayer, Peter</style></author><author><style face="normal" font="default" size="100%">Carell, Thomas</style></author><author><style face="normal" font="default" size="100%">Chatgilialoglu, Chryssostomos</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">{Independent Generation of C5‘-Nucleosidyl Radicals in Thymidine and 2‘-Deoxyguanosine}</style></title><secondary-title><style face="normal" font="default" size="100%">J. Org. Chem.</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">may</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://pubs.acs.org/doi/abs/10.1021/jo062518c</style></url></web-urls></urls><number><style face="normal" font="default" size="100%">10</style></number><volume><style face="normal" font="default" size="100%">72</style></volume><pages><style face="normal" font="default" size="100%">3659–3666</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">(Chemical Equation Presented) The synthesis of the C5′ tert-butyl ketone of thymidine 1a and 2′-deoxyguanosine 2 is achieved by reaction of 5′-C-cyano derivatives with tert-butyl lithium followed by acid hydrolysis. The 5′R configuration is assigned by X-ray crystal structure determination of an opportunely protected derivative of 1a. The (5′S)-isomers of both nucleosides are not stable, and a complete decomposition occurs in the reaction medium. The photochemistry of 1a and 2 effectively produced the thymidin-5′-yl radical and the 2′-deoxyguanosin-5′-yl radical, respectively. In the thymidine system, the C5′ radical is fully quenched in the presence of a physiological concentration of thiols. In the 2′-deoxyguanosine system, the C5′ radical undergoes intramolecular attack onto the C8-N7 double bond of guanine leading ultimately to the 5′,8-cyclo-2′-deoxyguanosine derivative. The cyclization of the 2′-deoxyguanosin-5′-yl radical occurs with a rate constant of ca. 1 × 106 s-1 and is highly stereoselective affording only the (5′S)-diastereomer. © 2007 American Chemical Society.</style></abstract></record></records></xml>