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Base-modified octanucleotides derived from d(G1–G2–A–A–T–T–C–C–) ( 11 ) but containing 8-aza-7-deaza-2′-deoxyguanosine ( 2 ) instead of 2′-deoxyguanosine ( 1 ) have been prepared by solid-phase synthesis employing P(III) chemistry. Isobutyrylation of 2 , followed by 4, 4′-dimethoxytritylation and subsequent phosphitylation yielded the methyl or the cyanoethyl phosphoramidites 6a or 6b , respectively. They were used as building blocks in automated DNA synthesis. The resulting octanucleotides 12–14 containing 2 showed increased Tm values compared to the parent oligomer 11 . The oligomers 11 – 14 were employed as sequence-specific probes in endo-deoxyribonuclease Eco RI oligonucleotide recognition. Whereas displacement of dG-2 (enzymic cleavage site of 11 ) abolished phosphodiester hydrolysis, replacement of dG-1 enhanced the cleavage rate compared to 11 . 相似文献
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Driller KM Libnow S Hein M Harms M Wende K Lalk M Michalik D Reinke H Langer P 《Organic & biomolecular chemistry》2008,6(22):4218-4223
N-glycosides of 6H-indolo[2,3-b]quinoxalines were prepared and structurally characterized. The synthesis relies on the cyclocondensation of isatine-N-glycosides with 1,2-diaminobenzenes. Some products exhibit weak cytotoxic activity against human ceratinocytes (HaCaT). 相似文献
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The synthesis of 6-amino-1-(2′,3′-dideoxy-β-D -glycero-pentofuranosyl)-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one ( =8-aza-7-deaza-2′,3′-dideoxyguanosine; 1 ) from its 2′-deoxyribofuranoside 5a by a five-step deoxygenation route is described. The precursor of 5a, 3a , was prepared by solid-liquid phase-transfer glyscosylation which gave higher yields (57%) than the liquid-liquid method. Ammonoloysis of 3b furnished the diamino nucleoside 3c . Compound 1 was less acid sensitive at the N-glycosydic bond than 2′,3′-dideoxyguanosine ( 2 ). 相似文献
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