Oligonucleotide Analogues with Integrated Bases and Backbone

Abstract

AbstractThe thiomethylene‐linked U*[s]U(*) dimers 9–14 were synthesized by substitution of the 6‐[(mesyloxy)methyl]uridine 6 by the thiolate derived from the uridine‐5′‐thioacetates 7 and 8 followed by O‐deprotection. Similarly, the thiomethylene‐linked A*[s]A(*) dimers 9–14 were obtained from the 8‐(bromomethyl)adenosine 15 and the adenosine‐5′‐thioacetates 16 and 17. The concentration dependence of both HN(3) of the U*[s]U(*) dimers 9–14 evidences the formation of linear and cyclic duplexes, and of linear higher associates, C(8 or 6)CH2OH and/or C(5′/II)OH groups favouring the formation of cyclic duplexes. The concentration dependence of the chemical shift for both H2NC(6) of the A*[s]A(*) dimers 18–23 evidences the formation of mainly linear associates. The heteroassociation of U*[s]U(*) to A*[s]A(*) dimers is stronger than the homoassociation of U*[s]U(*) dimers, as evidenced by diluting equimolar mixtures of 11/20 and 13/22. A 1 : 1 stoichiometry of the heteroassociation is evidenced by a Job's plot for 11/20, and by mole ratio plots for 9/18, 10/19, 12/21, 13/22, and 14/23.