Nucleic Acids in Chemistry and Biology
the most nucleophilic heteroatom on the base component. Such syntheses have, therefore, been widely employed for the preparation ...
their great metabolic stability to the phosphorylase enzymes, which cleaves the glycosylic bond of normal nucleosides. The carbo ...
Aristeromycin was first prepared in racemic form by Shealy and Clayson in 1966 and its laevorotatory enantiomer was discovered 2 ...
Nucleosides and Nucleotides 91 N N N N X Y N N NH 2 O NH N O O Z NH N N N O NH 2 HO OAc MeOCO 2 OCO 2 Me MeOCO 2 B (+) 10 steps ...
purine, which can be converted into adenine or guanine as a result of metabolic deamination or hydroxy- lation (i.e.prodrugs, Se ...
through nucleophilic addition of the 5-hydroxyl group to C-6. The lower reactivity of iodine and the require- ment for acidic c ...
terminal alkynes to 5-iodo- or 5-triflate esters of 2-deoxyuridine (Figure 3.27). Coupling with allylamine or propargylamine (F ...
transformation has allowed the syntheses of several pyranopyrimidine nucleosides (Figure 3.27d) that have been shown to display ...
The Sonogashira substitution has also been widely employed by Seela in the syntheses of C7-modified 7-deazapurine (pyrrolo[2,3-d ...
Nucleosides and Nucleotides 97 AcO O AcO N NH O O X AcO O AcO N N N O X N N O HO HO N N NH 2 O X HO O HO N N Y O X X = H , F, NH ...
Oligonucleotides containing thioguanine have been used widely for studying RNA and DNA–protein interactions, as the thiocarbonyl ...
produces the 2-monoalkylated nucleoside together with the 2,3-bis alkylated by-product. Subsequent hydrolysis provides a simp ...
3.2 CHEMISTRY OF ESTERS AND ANHYDRIDES OF PHOSPHORUS OXYACIDS 3.2.1 Phosphate Esters The predominant forms of phosphorus in biol ...
oxygen atoms are non-equivalent (i.e.diastereotopic) and the phosphorus atom is a pro-chiral centre. By substituting one of thes ...
Both C O and P O cleavage pathways (which give the same overall products) are observed. For attack at phosphorus, associative (S ...
formation from phosphorus to the nucleophile and the leaving group. If this is greater in the transition state than in the start ...
basic conditions without competing cleavage of the oligonucleotide chain (Figure 3.47). Consequently, it is the protecting group ...
The essential observation is the acceleration of both ring closure and ring opening. Furthermore, exo- cyclic P O bond cleavage ...
5 -O-nucleoside residue. The enzymatic reaction is completed by the regioselective ring opening of the cyclic phosphate to give ...
very good leaving groups, the difference between mono- and dianion reactivity is small, but for poor leaving groups, the monoani ...
«
2
3
4
5
6
7
8
9
10
11
»
Free download pdf