Study of the Factors that Control the Ratio of the Products between 5-Fluorouracil, Uracil, and Tetrahydrobenzoxazepine <i>O</i>,<i>O</i>-Acetals Bearing Electron-Withdrawing Groups on the Nitrogen Atom
作者:Mónica Díaz-Gavilán、José A. Gómez-Vidal、Antonio Entrena、Miguel A. Gallo、Antonio Espinosa、Joaquín M. Campos
DOI:10.1021/jo052167m
日期:2006.2.1
derivatives for the Lewis acid mediated condensation reaction with pyrimidine bases to give O,N-acetals. Acetonitrile, stannic chloride, 50 °C, and a reaction time higher than 48 h are the optimum conditions for such condensation reactions. Under these conditions, 5-fluorouracil preferably links to the aminalic carbon through its N-1‘ ‘ position, while the attachment of the uracil fragment is through N-3‘ ‘
(RS)-1-(2-硝基苯磺酰基)-和(RS)-1-(4-硝基苯磺酰基)-3-甲氧基-1,2,3,5-四氢-4,1-苯并x庚因是比1-更好的底物酰基-3-甲氧基-1,2,3,5-四氢-4,1-苯并x并庚因衍生物,在路易斯酸介导的与嘧啶碱的缩合反应中生成O,N-乙缩醛。乙腈,氯化锡,50°C和高于48小时的反应时间是此类缩合反应的最佳条件。在这些条件下,5-氟尿嘧啶优选通过其N -1''位置连接至氨基碳,而尿嘧啶片段的连接通过N -3''或N-1''分别为环状或非环状产物。分析和讨论了影响反应过程的原因。所述的检查1核磁共振光谱揭示了单一形式的存在下,仲胺11和两种构象异构体的叔磺酰胺7a中,b,图9a,b,和图10b以及用于酰胺7D和13,具有以下的分布:7a,59/41; 7b,53/47;9a,52/48;9b,59/41; 10b,56/44;7d,50/50; 13,80/20。随着温度的升高,7b的1