Novel uridin-2′-yl carbamates:: synthesis, incorporation into oligodeoxyribonucleotides, and remarkable fluorescence properties of 2′-pyren-1-ylmethylcarbamate

A convenient method for the preparation of uridin-2'-yl carbamate derivatives is described. The stable 2'-O-(imidazol-1-ylcarbonyl)-3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)uridine, prepared from uridine, was treated with primary or secondary aliphatic amines to give 2'-carbamates in high yield. After 3',5'-O-deprotection with triethylamine trihydrofluoride, 5'-O-dimethoxytritylation, and 3'-O-phosphitylation with bis(N,N-diisopropyl-amino)-2-cyanoethoxyphosphine, modified phosphoramidites were obtained and used in machine-assisted synthesis of modified oligodeoxynucleotides containing uridin-2'-yl carbamate residues bearing various N-substituents. The influence of uridin-2'-yl carbamate moieties on the stability of modified oligonucleotide duplexes with complementary DNA and RNA was studied by thermal denaturation experiments. Pyrene-modified oligonucleotides showed a considerable increase influorescence intensity upon hybridisation to complementary RNA and interesting binding properties when hybridised to a mismatched DNA.