Nucleosides and Nucleotides. 108. Synthesis and Optical Properties of Syn-Fixed Carbon-Bridged Pyrimidine Cyclonuclesides.
作者:Yuichi YOSHIMURA、Brian A. OTTER、Tohru UEDA、Akira MATSUDA
DOI:10.1248/cpb.40.1761
日期:——
6, 1'-Propanouridine (10), a carbon-bridged cyclouridine fixed in the syn-conformation, was synthesized from D-fructose. Two additional carbon-units were introduced at the 1'-position of 1'-hydroxymethyl-O2, 2'-anhydrouridine 13 and inversion of the 2' hydroxyl group was achieved by sequential oxidation-reduction reactions. Finally, the spiro-carbon bridge was constructed by radical cyclization of the 1'-iodopropyl derivative of 5-chlorouridine. Dehydrochlorination followed by deprotection gave the desired 10. The circular dichroism (CD) spectrum of 10 showed a negative Cotton effect ([θ]=-6100) at the main absorption region, whereas 5'-O-tert-butyldimethylsilyl-2', 3'-O-isopropylidene-6, 1'-propanouridine (30) showed almost no Cotton band at the same absorption region. These results suggest that the critical region in which the CD Cotton effect changes from negative to positive is present in the syn region where 10 is located. Correlation of the magnitude and the direction of the sign of the CD Cotton effect and the torsion angle (χ) is also discussed.
6, 1'-丙尿苷 (10) 是一种以顺式构象固定的碳桥环尿苷,由 D-果糖合成。在1'-羟甲基-O2、2'-脱水尿苷13的1'位引入两个额外的碳单元,并通过连续的氧化还原反应实现2'羟基的反转。最后,通过5-氯尿苷的1'-碘丙基衍生物的自由基环化构建了螺碳桥。脱氯化氢,然后脱保护得到所需的10。10的圆二色性(CD)光谱在主吸收区域显示负Cotton效应([θ]=-6100),而5'-O-叔丁基二甲基甲硅烷基-2', 3'-O-异亚丙基-6, 1'-丙尿苷 (30) 在同一吸收区域几乎没有显示出 Cotton 谱带。这些结果表明,CD Cotton效应从负值变为正值的关键区域存在于10所在的syn区域中。还讨论了 CD Cotton 效应的符号大小和方向与扭转角 (χ) 的相关性。