Nucleotides. LXXIV Synthesis of a-D-Arabino-oligonucleotides
摘要:
The 5 alpha-D-arabinofuranosylnucleosides alpha-araU (15), alpha-araT (18), alpha-araC (22), alpha-araA (25), and alpha-araG (28) have been synthesized by the modified silyl-method. The amino groups at the nucleobases and the 2'-hydroxy group at the sugar moiety were protected by the 2-(4-nitro-phenyl) ethoxycarbonyl (npeoc) group (37-40) and the amide function in alpha-araG was additionally blocked by the 2-(4-nitrophenyl)ethyl group (63) to improve solubility in organic solvents. Mono-and dimethoxytritylation of the 5'-OH group was performed in the usual manner to give 41-48, 64, and 65 in high yields and further substitution of the 3'-OH group led to the monomeric building blocks 66-75 as well as the 3'-O-succinoyl derivatives 76-85 functioning as starting units in solid-support oligonucleotide synthesis. A large number of oligo-alpha-arabinonucleotides have been prepared on modified CPG-material applying the npeoc/npe strategy as a very efficient synthetic tool for highly purified, homogenous oligomers. Hybridizations between alpha-arabinonucleotide strands revealed in analogy to earlier findings an antiparallel orientation whereas the combination of an oligo-alpha-D-arabinonucleotide with a complementary oligo-2'-deoxy-beta-D-ribofuranosylnucleotide showed base-pairing only if a parallel polarity was present. The advantages in oligo-alpha-arabinonucleotide synthesis were furthermore demonstrated by the synthesis of the t alpha-ANA(his) a structural analog of the natural tRNA(his) of the phage T5.
A Procedure for Facile Synthesis of Nucleosides Using N, O-Bistrimethylsilylacetamide in the Presence of Natural Phosphate Coated with Potassium Iodide
作者:Laila Baddi、Michael Smietana、Said Sebti、Jean-Jacques Vasseur、Hassan B. Lazrek
DOI:10.2174/157017810791112441
日期:2010.4.1
yields under mild conditions by N-glycosylation of 1-O-acetyl D/L- arabino, and xylofuranose, with silylated nucleobases (uracil, thymine and 6- azauracil) in acetonitrile using natural phosphate (NP) coated with potassiumiodide in BSA as catalyst.
Condensation of 1-Fluorofuranoses and Silylated Nucleobases Catalyzed by Tetrafluorosilane
作者:Ryoji Noyori、Masahiko Hayashi
DOI:10.1246/cl.1987.57
日期:1987.1.5
The title reaction provides a generally useful tool for nucleosidesynthesis. The stereoselectivities are highly influenced by the fluoride substrates, and steric course of the reaction of O-benzylated ribofuranosyl fluoride is solvent dependent.