Method for Preparing New Flavin Derivatives:  Synthesis of Flavin−Thymine Nucleotides and Flavin−Oligonucleotide Adducts Christelle Frier Jean-Luc Décout Marc Fontecave 10.1021/jo962361w.s001 https://acs.figshare.com/articles/journal_contribution/Method_for_Preparing_New_Flavin_Derivatives_Synthesis_of_Flavin_Thymine_Nucleotides_and_Flavin_Oligonucleotide_Adducts/3705468 In order to link to the 5‘-end of oligonucleotides the flavin analogs <b>9a</b>,<b>b</b> possessing only one terminal hydroxy group on the side chain, the phosphoramidite and the H-phosphonate coupling methods were developed. Surprisingly, after reaction of compounds <b>9a,b</b> with 2-cyanoethyl <i>N</i>,<i>N</i>-diisopropylchlorophosphoramidite, the flavin phosphoramidates <b>11a,b </b>were isolated instead of the expected phosphoramidite derivatives <b>10a,b</b>. A very efficient photooxidation process occurred probably during the isolation of the products. From the prepared flavin H-phosphonates <b>12a,b</b>, flavin−thymine nucleotides and flavin−oligonucleotide adducts were synthesized for the first time. The versatility of the method was demonstrated in the oxidation step with the synthesis of the flavin−thymine nucleotides <b>15</b>−<b>17</b> possessing a phosphodiester, a phosphorothioate, and a methyl phosphate linkage, respectively. This method is of general interest with regard to the extensive research developed for preparing flavin analogs and modified oligonucleotides possessing interesting biological or/and catalytic properties. 1997-05-30 00:00:00 flavin analogs phosphoramidite derivatives 10 side chain photooxidation process method compounds 9 flavin phosphoramidates 11 terminal hydroxy group methyl phosphate linkage oxidation step flavin analogs 9 Flavin