Saha M, Kresbach G M, Giese R W, Annan R S, Vouros P
Department of Medicinal Chemistry, Northeastern University, Boston, Massachusetts.
Biomed Environ Mass Spectrom. 1989 Nov;18(11):958-72. doi: 10.1002/bms.1200181103.
Pentafluorobenzyl (PFBz) derivatives of the following nucleobases were prepared: cytosine, 5-methylcytosine, O2-methylcytosine, O2-ethylthymine, O4-ethylthymine, 5-hydroxymethyluracil, N6-methyladenine, O6-methylguanine, O6-hydroxyethylguanine and O6-hydroxyethylpurine. 13C nuclear magnetic resonance was diagnostic for O- versus N-attachment of the PFBz moiety: the resonance of the methylene carbon appeared in the range 29.15-42.13 ppm for NCH2C6F5, and 58.45-69.01 for OCH2C6F5. Considerable structural information was provided by mass spectrometry with ionization by electron impact. All of the derivatives were detected with high sensitivity and specificity by gas chromatography with detection by electron capture negative ion mass spectrometry, reflecting not only their chemical and physical stability, but also their strong tendency to form a structurally diagnostic anion, [M - PFBz]-, in high yield under these ionization conditions. PFBz derivatives are therefore attractive forms of alkyl-substituted nucleobases for analysis by mass spectrometry.
制备了以下核碱基的五氟苄基（PFBz）衍生物：胞嘧啶、5-甲基胞嘧啶、O2-甲基胞嘧啶、O2-乙基胸腺嘧啶、O4-乙基胸腺嘧啶、5-羟甲基尿嘧啶、N6-甲基腺嘌呤、O6-甲基鸟嘌呤、O6-羟乙基鸟嘌呤和O6-羟乙基嘌呤。13C核磁共振可诊断PFBz部分的O-与N-连接：对于NCH2C6F5，亚甲基碳的共振出现在29.15 - 42.13 ppm范围内，对于OCH2C6F5则出现在58.45 - 69.01 ppm范围内。电子轰击电离质谱提供了大量结构信息。通过电子捕获负离子质谱检测的气相色谱法以高灵敏度和特异性检测到所有衍生物，这不仅反映了它们的化学和物理稳定性，还反映了它们在这些电离条件下以高产率形成结构诊断性阴离子[M - PFBz]-的强烈倾向。因此，PFBz衍生物是用于质谱分析的烷基取代核碱基的有吸引力的形式。
