A stereoselective radical-mediated hydrogermylation of the protected 5-ethynyluracil nucleosides with trialkyl-, triaryl,- or tris(trimethylsilyl)germanes gave (Z)-5-(2-germylvinyl)uridine, 2′-deoxyuridine, or ara-uridine as major products. Reaction of the β-triphenylgermyl vinyl radical intermediate with oxygen and fragmentation of the resulting peroxyradical provided also 5-[2-(triphenylgermyl)acetyl]pyrimidine
受保护的5-
乙炔基尿
嘧啶核苷与三烷基- ,三芳基,的立体选择性自由基介导的hydrogermylation -或三(三甲
硅烷基)
锗,得到(ż)- 5-(2- germylvinyl)
尿苷,
2'-脱氧尿苷,或
ARA -
尿苷作为主要产品。β-三苯基
锗烷基
乙烯基自由基中间体与氧的反应和所得过氧自由基的断裂也以低至中等产率提供了5-[2-(三苯基
锗烷基)乙酰基]
嘧啶核苷。后者在 MeOH 中的热异构化通过四中心活化的复合物发生,随后所得O-
锗基取代的烯醇的
水解以定量产率产生 5-乙酰尿
嘧啶核苷。