5′-C-branched thymidines: Synthesis, stereochemistry, and incorporation into oligodeoxynucleotides

Surface modification and in vitro blood compatibilities of polyurethanes containing z‐lysine segments in the main chain

“…This epoxide had been obtained in three steps from 3′‐ O ‐( tert ‐butyldimethylsilyl)thymidine 5. 12 Oxidation and Wittig olefination gave the 5′‐methylene derivative in high yield, whereas the final mCPBA‐mediated oxidation of the alkene gave 6 as the pure 5′ ( S )‐isomer in a more modest 42 % yield 5. Several attempts failed to improve on the epoxidation, including mCPBA oxidation under microwave irradiation, Payne oxidation,13 methyltrioxorhenium(VII) (MTO), H 2 O 2 and pyridine,14 as well as DCC and H 2 O 2 15…”

“…The corresponding phosphoramidites for incorporating monomers N , O and P were synthesised by the CuAAC reaction 11. Introduction of the azido group in 6 by using a known protocol gave 10 ,12 and protection of the 5′‐hydroxy group by pixylation gave the key azide substrate, 11 . Formation of the triazole derivatives was achieved by using phenylacetylene, N 1‐benzoyl‐5‐ethynyluracil, which was made from 5‐(trimethylsilyl)ethynyluracil17 (see the Supporting Information), and trimethylsilylacetylen to give the nucleosides 12 , 15 and 18 , respectively, in high yields (81–97 %).…”

New Light-Sensitive Nucleosides for Caged DNA Strand Breaks

“…First we envisaged the development of a synthetic pathway to form the 5′ C ‐modified building blocks (Scheme ). Treatment of aldehyde 6 4 with o ‐nitrophenyl lithium (generated through metal–halide exchange) and subsequent transformation of the diastereomeric alcohols into the corresponding acetals yielded 7 a and 7 b in a ratio of 4.5:1 (5′ S :5′ R ) 5, 6. The diastereomers 7 a and 7 b were separated easily by flash column chromatography, converted into 8 a and 8 b , and incorporated into oligonucleotides by standard automated DNA synthesis except that, for the modified nucleotides, the 5′‐deprotection and coupling times were extended to 2 and 15 minutes, respectively.…”

Stereoselective Synthesis of (5′S)-5′-C-(5-Bromo-2-penten-1-yl)-2′-deoxyribofuranosyl Thymine, a New Convertible Nucleoside

“…Preliminary studies that we have performed on 5Ј-tosyloxypropylthymidine showed that pyridinium or aminoguanidinium can also be coupled under the same conditions. [8] The ∆Tm values observed for the diamine-oligonucleotide conjugates A* and B* (ϩ0.5°and Ϫ0.6°per modification) should be compared with those observed when aminomethyl (Ϫ0.3°), methoxymethyl (Ϫ0.6°) and allyl (Ϫ1.4°) moieties are introduced as (5ЈS)-5Ј-C-substituents on thymidine [14] and Ϫ with more caution, since those modified thymidine were used as 5Ј-C epimeric mixtures Ϫ with the values found when methyl (0°to Ϫ0.2°) and hydroxymethyl (Ϫ1°to Ϫ2°) moieties are introduced. [15Ϫ16] The longer the chain length, the greater the destabilisation of hybridisation.…”