Treatment of ribonucleosides with thionyl chloride/pyridine/acetonitrile (0 °C to ambient temperature) resulted in essentially quantitative formation of 5′-chloro-5′-deoxy-2′,3′-O-sulfinylnucleoside derivatives. These diastereomeric sulfite esters underwent deprotection readily with aqueous methanolic ammonia. This gave 5′-chloro-5′-deoxynucleosides without use of the suspected carcinogen, hexamethylphosphoramide (HMPA). Nucleophilic displacement with sodium thiolates in dimethylformamide (−30 °C to ambient temperature) gave 5′-S-aryl(or alkyl)-5′-thionucleosides in high yields. Treatment of ribonucleosides with thionyl chloride/acetonitrile without pyridine followed by aqueous work-up gave diastereomeric 2′,3′-O-sulfinylnucleosides with an unmodified 5′-hydroxyl group. Diagnostic NMR shifts for cyclic sulfite ester stereochemistry are noted. Key words: adenosine, 5′-S-aryl(or alkyl)-5′-thionucleosides, 5′-chloro-5′-deoxynucleosides, uridine, nucleosides.
使用硫酰氯/吡啶/乙腈(0°C至室温)处理核糖核苷可基本定量形成5'-氯-5'-脱氧-2',3'-O-亚磺酰核苷衍生物。这些对映异构的亚硫酸酯酯可以轻松地通过甲醇氨水溶液去保护基。这样就可以不使用疑似致癌物六甲基磷酰胺(HMPA)制备5'-氯-5'-脱氧核苷。在二甲基甲酰胺中,通过钠硫醇的亲核置换反应(-30°C至室温),可以高产得到5'-S-芳基(或烷基)-5'-硫代核苷。使用硫酰氯/乙腈而不是吡啶处理核糖核苷,然后进行水处理,可以得到未修饰的5'-羟基核苷的对映异构的2',3'-O-亚磺酰核苷。文中还提到了环状亚硫酸酯立体化学的诊断NMR位移。关键词:腺苷,5'-S-芳基(或烷基)-5'-硫代核苷,5'-氯-5'-脱氧核苷,尿苷,核苷。