Bretner M, Kulikowski T, Dzik J M, Balińska M, Rode W, Shugar D
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa.
J Med Chem. 1993 Nov 12;36(23):3611-7. doi: 10.1021/jm00075a016.
A convenient synthesis of 5-fluoro-2-thiouracil (11) is based on hydrolytic deamination of 5-fluoro-2-thiocytosine (9). Lewis acid-catalyzed condensation of di-TMS-5-fluoro-2-thiouracil (13) or di-TMS-2-thiouracil (14) with 2-deoxy-3,5-di-O-p-toluyl-D-ribofuranosyl chloride (15) led to mixtures of the beta- and alpha-anomers of 3',5'-toluylated 2'-deoxy-5-fluoro-2-thiouridine (16 and 18) or 2'-deoxy-2-thiouridine (17 and 19), each of which was deblocked with MeOH-NH3 to give the desired free anomeric nucleoside pairs 1, 5 and 3, 7, respectively. These were selectively converted to the corresponding 5'-monophosphates 2, 6 and 4, 8, with the aid of the wheat shoot phosphotransferase system. Conformations of the nucleosides 1, 3, 5, 7 are deduced from 1H NMR spectra, and circular dichroism spectra for nucleotide anomeric pairs 2, 6 and 4, 8 are reported. Whereas beta-2-thio-dUMP (4) was a good substrate (Km approximately 10(-5) M), beta-5-fluoro-2-thio-dUMP (2) proved to be a potent competitive, slow-binding inhibitor (Ki approximately 10(-8) M) of the purified enzymes from Ehrlich ascites carcinoma and L1210 cells. The alpha-anomer 6 was a weak inhibitor, with Ki in the mM range, and its congener 8 hardly interacted with the enzyme. The beta-anomer 1 exhibited antitumor activity in a mouse leukemic cell line L5178Y (IC50 approximately 10(-6) M), hence 40-100-fold weaker than 5-fluoro-dUrd. Its alpha-anomer 5 was 10-fold less active, but exhibited at least 10-fold higher selectivity with respect to the tumor cells than the beta-anomer 1.
5-氟-2-硫尿嘧啶（11）的简便合成方法是基于5-氟-2-硫代胞嘧啶（9）的水解脱氨反应。二-TMS-5-氟-2-硫尿嘧啶（13）或二-TMS-2-硫尿嘧啶（14）与2-脱氧-3,5-二-O-对甲苯甲酰基-D-核糖呋喃糖基氯（15）在路易斯酸催化下缩合，得到3',5'-甲苯酰化的2'-脱氧-5-氟-2-硫代尿苷（16和18）或2'-脱氧-2-硫代尿苷（17和19）的β-和α-异头物混合物，每一种混合物都用甲醇-氨脱保护，分别得到所需的游离异头核苷对1、5和3、7。借助小麦芽磷酸转移酶系统，将它们选择性地转化为相应的5'-单磷酸酯2、6和4、8。核苷1、3、5、7的构象由1H NMR光谱推导得出，并报道了核苷酸异头物对2、6和4、8的圆二色光谱。虽然β-2-硫代-dUMP（4）是一种良好的底物（Km约为10^(-5) M），但β-5-氟-2-硫代-dUMP（2）被证明是来自艾氏腹水癌和L1210细胞的纯化酶的一种强效竞争性、慢结合抑制剂（Ki约为10^(-8) M）。α-异头物6是一种弱抑制剂，Ki在毫摩尔范围内，其同系物8与该酶几乎不相互作用。β-异头物1在小鼠白血病细胞系L5178Y中表现出抗肿瘤活性（IC50约为10^(-6) M），因此比5-氟-dUrd弱40-100倍。其α-异头物5的活性低10倍，但相对于肿瘤细胞，其选择性比β-异头物1至少高10倍。
