Synthesis of 2'-modified oligodeoxynucleotides via on-column conjugation.
Oligodeoxynucleotides modified at the 2'-position of 2'-amino-2'-deoxyuridine or uridine were prepared in high yield and purity using phosphoramidites 2 and 3, respectively. Oligodeoxynucleotide conjugates were prepared on the solid-phase synthesis support following selective unmasking of the nucleophile incorporated in these phosphoramidites. Synthesis of oligodeoxynucleotides modified at the 2'-position of an internal nucleotide provides molecules that are complementary to those previously prepared via a similar approach using C5-substituted pyrimidines. The efficiency of functionalization of the 2'-O-alkylamino-uridine derived from 3 in a protected oligodeoxynucleotide was less susceptible to steric hindrance than the 2'-amino-2'-deoxyuridine in the same polymeric substrate. However, the greater reactivity of the 2'-O-alkylamine containing nucleotide gave rise to undesired acetamide formation resulting from nucleophilic attack on the 5'-terminal acetate in capped failure sequences. This problem was overcome by using 2,2,2-trimethylacetyl anhydride as a capping agent during the automated synthesis cycles. Finally, the efficiency of the photochemical unmasking of the support bound alkylamine on a 1 mumole scale was improved by using two 20 min photolysis cycles, coupled with removing reaction byproducts between cycles.
Hwang
J T
JT
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Greenberg
M M
MM
D000577:Amides; D001483:Base Sequence; D003857:Deoxyuridine / Q000031:analogs & derivatives*; D007202:Indicators and Reagents; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000737:chemistry; D010756:Phosphoric Acids; D012116:Resins, Plant; D014529:Uridine
C410434:2'-amino-2'-deoxyuridine; D000577:Amides; D007202:Indicators and Reagents; D009838:Oligodeoxyribonucleotides; D010756:Phosphoric Acids; D012116:Resins, Plant; C011067:phosphoramidic acid; D003857:Deoxyuridine; D014529:Uridine