Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• Organische Chemie, Universität Münster, Corrensstrasse 40, 48149 Münster, Germany 10.3762/bjoc.14.217 Abstract Copper(I)-promoted "click" cyclization in the presence of TBTA afforded nucleoside macrocycles in very high yields (≈70%) without using protecting groups. To this end, dU and dC derivatives

• and 1H,1H-NMR coupling constants. The sugar conformation (N vs S) was different in solution as compared to the solid state. Keywords: click cyclization; conformation; macrocycles; nucleosides; X-ray; Introduction The field of macrocycles was initiated by the work of Ruzicka and his structure

• performed on dC was carried out with 5-(1,7-octadiynyl)-dU (6) [32][33][44]. The latter was converted to 5’-azido-dU 7 using the same reaction conditions as described above (Scheme 2). By this means, compound 7 was isolated in 73% yield. Then, click cyclization was performed. In contrast to the cyclic dC