Acyclic Nucleic Acid Analogues: Synthesis and Oligomerization of γ,4-Diamino-2-oxo-1(2H)-pyrimidinepentanoic Acid and δ,4-Diamino-2-oxo-1(2H)-pyrimidinehexanoic Acid

Article abstract of DOI:10.1021/jo00021a010

Alkylation of the tosylates of N-t-Boc-5-(hydroxymethyl)-2-pyrrolidinone and N-t-Boc-6-(hydroxymethyl)-2-piperidinone with the sodium salt of cytosine in dimethyl sulfoxide, followed by acylation of the base exocyclic amine and selective opening of the lactam ring by alkaline hydrolysis, gave the title compounds, respectively, in protected form.Oligomerization was achieved by activation of the carboxylic group as the p-nitrophenyl ester and coupling with the free amine of another subunit in dimethlformamide or dimethyl sulfoxide.A hexamer of the pentanoic acid system could be easily prepared by stepwise coupling of the monomeric units or by block synthesis via trimers.The hexanoic acid derived hexamer could only be prepared by stepwise elongation, mostly due to problems of solubility for this backbone.