Nucleobase analogues

Hattori H, et al. Nucleosides and nucleotides. 158. l-(3-C-ethynyl-P-D-ribo-pentofuranosyl)-cytosine, 1 -(3-C-ethynyl-P-D-ribo-pentofuranosyl)uracil, and their nucleobase analogues as new potential multifunctional antitumor nucleosides with a broad spectrum of activity. J Med Chem 1996 39 5005. 

By reacting N-functionalized imidazole-4,5-dicarboxylates 77 with guanidine-HCl and NaOMe/MeOH, Hosmane et al. prepared a series of ring-expanded nucleoside analogues 79 ( fat nucleobase analogues) (Equation 12), which... 

Figure 1. (a) The structure of an oligonucleotide composed of the four naturally occurring nucleotides adenine (A), guanine (G), cytosine (C), and thymine (T). (b) The structures of nucleobase analogues employed in electron transfer studies, and abbreviations used in this chapter. 

The nucleobase analogue 7,8-dihydro-8-oxoguanine (OG Figure lb) is of particular interest as a likely intermediate in the oxidation of guanine [6, 7], Calculations by Prat et al. [39] indicate that the IP of OG is c. 0.4 eV lower than that of G. Stacking of OG with guanine (either 3 or 5 ) results in a further decrease in the IP of OG. 

The syntheses of six different ribonucleoside phosphoramidites with fluorobenzenes or fluorobenzimidazoles as nucleobase analogues and of one inosine analogue have been described. Lithiation of the required bromoarene with BuLi was followed by its addition to 2,3,5-tri-O-benzyl-D-ribono-1,4-lac-tone to yield an intermediate lactol which was directly dehydroxylated with triethylsilane and BFj-OEti to afford stereoselectively the respective precursors to (57a-f).""... 

Two-photon excitation of the fluorescent nucleobase analogues 2-aminopurine and cytosine analog l,3-diaza-2-oxophenothiazine has been studied. " ... 

The synthesis of the cyclobutane derivative 76, as well as its enantiomer, by a noncarbohydrate method has been achieved. These compounds are useful for preparing nucleobase analogues. 

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