55662-33-4Relevant articles and documents
Duplex DNA and DNA-RNA hybrids with parallel strand orientation: 2′-deoxy-2′-fluoroisocytidine, 2′-deoxy-2′-fluoroisoguanosine, and canonical nucleosides with 2′-fluoro substituents cause unexpected changes on the double helix stability
Ingale, Sachin A.,Leonard, Peter,Tran, Quang Nhat,Seela, Frank
, p. 3124 - 3138 (2015/03/30)
Oligonucleotides with parallel or antiparallel strand orientation incorporating 2′-fluorinated 2′-deoxyribonucleosides with canonical nucleobases or 2′-deoxy-2′-fluoroisocytidine (FiCd, 1c) and 2′-deoxy-2′-fluoroisoguanosine (FiGd, 3c) were synthesized. To this end, the nucleosides 1c and 3c as well as the phosphoramidite building blocks 19 and 23 were prepared and employed in solid-phase oligonucleotide synthesis. Unexpectedly, FiCd is not stable during oligonucleotide deprotection (55 °C, aq NH3) and was converted to a cyclonucleoside (14). Side product formation was circumvented when oligonucleotides were deprotected under mild conditions (aq ammonia-EtOH, rt). Oligonucleotides containing 2′-fluoro substituents (FiCd, FiGd and fluorinated canonical 2′-deoxyribonucleosides) stabilize double-stranded DNA, RNA, and DNA-RNA hybrids with antiparallel strand orientation. Unexpected strong stability changes are observed for oligonucleotide duplexes with parallel chains. While fluorinated oligonucleotides form moderately stable parallel stranded duplexes with complementary DNA, they do not form stable hybrids with RNA. Furthermore, oligoribonucleotide duplexes with parallel strand orientation are extremely unstable. It is anticipated that nucleic acids with parallel chains might be too rigid to accept sugar residues in the N-conformation as observed for ribonucleosides or 2′-deoxy-2′-fluororibonucleosides. These observations might explain why nature has evolved the principle of antiparallel chain orientation and has not used the parallel chain alignment.
SYNTHESES AND ALKALINE HYDROLYSES OF 2,2'-IMINO- AND 2,2'-(SUBSTITUTED IMINO)-1-(2'-DEOXY-β-D-ARABINOFURANOSYL)URACILS
Minamoto, Katsumaro,Azuma, Kishiko,Tanaka, Toshihiro,Iwasaki, Hiroshi,Eguchi, Shoji,et al.
, p. 2955 - 2962 (2007/10/02)
In order to examine the possibility of 'up' amination of sugar part of pirimidine nucleosides through pyrimidine N-cyclonucleosides, 2,2'-imino-1-(2'-deoxy-β-D-arabinofuranosyl)uracil (6g) and various N-substituted derivatives of (6g), (6a-f) were synthesized by amination-cyclization reactions of 2'-O-tosyl-2,5-anhydrouridine (5).The latter was synthesized from 2,5'-anhydrouridine (4) by 2',3'-O- dibutylstannylation followed in situ tosylation.N-p-Methoxyphenylisocytidine (7) obtainable from (4) was also cyclized to (6d) by treatment with 1,1'carbonyldi-imidazole. 2,2'-Arylamino analoques (6c,d) were hydrolysed with 2M NaOH-MeOH (1:1) e xtremely rapidly to give 2'-deoxy-2'arylamino uracil-arabinosides (8a,b).The 2',3'-dideoxy-2',3'-(N-phenyl)imino analoque of arabinoside (8a),(9), was used for the purpose of structural corroboration of (8a,b).Similar dehydrative cyclization of (6g) gave the 5',N-anhydro derivative, compound (10), while alkali-treatment gave a fragmentation product, imidazopyrimidin-7(8H)-one (11).Spectroscopic arquments which support structures (6), (10), and (11) are also presented.
