Parallel-Stranded DNA Formed by New Base Pairs Related to the Isoguanine-Cytosine or Isocytosine-Guanine Motifs
摘要:
Parallel-stranded (ps) oligonucleotide duplexes containing several new base pairs formed between 7-deazaisoguanine and cytosine, 8-aza-7-deaza-isoguanine and cytosine, and 5-aza-7-deaza guanine and guanine are described. The stability of the ps-hybrids increased if the duplex contains 8-aza-7-deazaisoguanine instead of isoguanine and is decreased by 7-deazaisoguanine incorporation. The purine-purine base pair between 5-aza-7-deazaguanine and guanine was found to be more stable than that of 5-methylisocytosine with guanine.
synthesis of 2′-deoxyisoguanosine (2), and the pyrrolo[2,3-d]pyrimidine and pyrazolo[3,4-d]pyrimidine 2′-deoxyribonucleosides 3 and 4 is described. Condensation of the imidazole precursor 5 with benzoyl isocyanate followed by reaction with ammonia gave 2. Its N(7) regioisomer was obtained from 6. Compound 2 was also prepared by the photochemically induced conversion of 2-Chloro- and 2-bromopurine 2′-deoxyribofuranosides
描述了2'-脱氧异鸟苷(2),吡咯并[2,3- d ]嘧啶和吡唑并[3,4- d ]嘧啶2'-脱氧核糖核苷3和4的合成。咪唑前体5与苯甲酰基异氰酸酯缩合,然后与氨反应,得到2。它的N(7)区域异构体是从6获得的。还通过分别在水溶液中将2-氯-和2-溴嘌呤2'-脱氧核糖呋喃糖苷9a和10进行光化学诱导的转化来制备化合物2,进一步将光反应用于化合物3的合成。和4分别从氨基-氯-2'-脱氧核苷9b和9c开始。
Oligonucleotide duplexes containing N<sup>8</sup>-glycosylated 8-aza-7-deazaguanine and self-assembly of 8-aza-7-deazapurines on the nucleoside and the oligomeric level
作者:Frank Seela、Rita Kröschel
DOI:10.1039/b309485p
日期:——
8-aza-7-deazaguanine N8-(2'-deoxy-beta-D-ribofuranoside) (1) was synthesized, converted into the phosphoramidite 4 and incorporated into oligonucleotides. Nucleoside 1 forms stable base pairs with 2'-deoxy-5-methylisocytidine in DNA with antiparallel chainorientation (aps) and with 2'-deoxycytidine in duplexes with parallelchains (ps). According to the CD spectra self-complementary oligonucleotides d(1-m5isoC)3