Adams D R, Boyd A S, Ferguson R, Grierson D S, Monneret C
Chemistry Department, Heriot-Watt University, Riccarton, Edinburgh, UK.
Nucleosides Nucleotides. 1998 Jun;17(6):1053-75. doi: 10.1080/07328319808004220.
1,3-Dipolar cycloaddition of 1-vinylthymine to azides, nitrile oxides, nitrones and nitronates has been investigated as a route to heterocyclic nucleoside analogues in which the nucleoside ribose moiety has been replaced by an alternative heterocycle. Reaction of 1-vinylthymine with highly reactive nitrile oxides affords 1-(isoxazolin-5-yl)thymine products in excellent yield at room temperature. The less reactive nitrone dipoles undergo cycloaddition to 1-vinylthymine at elevated temperature to afford 1-(isoxazolidin-5-yl)thymine cycloadducts in good-to-moderate yields, but show a tendency to eliminate thymine from the cycloaddition products over long reaction times. Azide cycloadditions to 1-vinylthymine proceed only under forcing conditions to which the fragile triazoline products are unstable.
研究了1-乙烯基胸腺嘧啶与叠氮化物、腈氧化物、硝酮和硝酯的1,3-偶极环加成反应，以此作为合成杂环核苷类似物的一条途径，其中核苷核糖部分已被另一种杂环取代。1-乙烯基胸腺嘧啶与高活性腈氧化物反应，在室温下以优异的产率得到1-(异恶唑啉-5-基)胸腺嘧啶产物。活性较低的硝酮偶极体在高温下与1-乙烯基胸腺嘧啶发生环加成反应，以良好至中等的产率得到1-(异恶唑烷-5-基)胸腺嘧啶环加合物，但在较长反应时间内显示出从环加成产物中消除胸腺嘧啶的趋势。1-乙烯基胸腺嘧啶的叠氮环加成反应仅在苛刻条件下进行，而脆弱的三唑啉产物对此不稳定。
