Dioxaphosphorinane-Constrained Nucleic Acid Dinucleotides as Tools for Structural Tuning of Nucleic Acids

Scheme 4

Synthesis of δ, ε, ζ-Dioxaphosphorinane-Constrained Nucleic Acid dinucleotides (δ,ε,ζ-D-CNA). Reagents and conditions: (i) DMTrCl, DMAP, pyr, 90%, (ii) TBAF, THF, 95% and (iii) 5′-thymidine phosphoramidites, 1H-tetrazole, acetonitrile, then I₂/H₂O, 90%, (iv) 3% TFA, DCM, 95%, (v) Et₃N, acetonitrile, 60°C, quant, and (vi) 1-(mesitylene-2-sulfonyl)-3-nitro-1,2,4-triazole (MSNT), pyr, 80°C, quant, (vii) TBAF, THF, 90%.