844681-04-5Relevant articles and documents
Oligonucleosides with a nucleobase-including backbone: Part 11. Linear and convergent synthesis of ethynylene-linked uridine-derived oligomers
Eppacher, Simon,Solladie, Nathalie,Vasella, Andrea
, p. 2926 - 2942 (2004)
A linear and a convergent synthesis of uridine-derived backbone-base- dedifferentiated (backbone including) oligonucleotide analogues were compared. The Sonogashira cross-coupling of the alkyne 1 and the iodide 2 gave the dimer 4 that was C-desilylated and again coupled with 2 to give the trimer 6 (Scheme 1). Repeating this linear sequence led to the pentamer 10. Coupling yields were satisfactory up to formation of the trimer 6, but decreased for the coupling to higher oligomers. Similarly, coupling of the alkynes 5, 7, and 9 with the iodouridine 3 gave, in decreasing yields, the trimer 12, tetramer 13, and pentamer 14, respectively. The dimeric iodouracil 20 was synthesized by coupling the alkyne 17 with the iodide 16 to the dimer 18, followed by iodination at C(6/I) to 19 and O-silylation (Scheme 2). The iodinated dimer 23 was prepared by iodinating and O-silylating the known dimer 21. Coupling of 20 and 23 with the dimer 5, trimer 7, and tetramer 9 gave the tetramers 8 and 13, the pentamers 10 and 14, and the hexamer 15, respectively (Scheme 3). The oligomers up to the pentamer 14 were deprotected to provide the trimer 24, tetramer 25, and pentamer 26 (Scheme 4). There was no evidence for the heteropairing of the pentamer 26 and rA7, nor for the pairing of rU5 and rA7, while a UV melting experiment showed the beginning of a sigmoid curve for the interaction of rU7 with rA7. Therefore, the pentamer 26 does not pair more strongly with rA7 than rU5.
