A Highly Stereoselective Samarium Diiodide-Promoted Aldol Reaction with 1‘-Phenylseleno-2‘-keto Nucleosides. Synthesis of 1‘α-Branched Uridine Derivatives
作者:Tetsuya Kodama、Satoshi Shuto、Satoshi Ichikawa、Akira Matsuda
DOI:10.1021/jo020266j
日期:2002.11.1
the corresponding samarium enolate, which was highly stereoselectively condensed with aldehydes, such as PhCHO, MeCHO, i-PrCHO, or (CH(2)O)(n)(), to give the corresponding 1'alpha-1' 'S-branched products 12a-d. This is the first time an enolate has been generated by reductively cleaving a C-Se bond. The highly selective stereochemical results suggest that the aldol reaction proceeds via a chelation-controlled
由于1'-支链核苷在药物化学中是生物学上重要的靶标,因此需要更有效的制备方法。1'α支化尿苷衍生物已成功地通过二碘化((SmI(2))促进的羟醛反应合成。用SmI(2)在THF中于-78℃下用SmI(2)处理易于从尿苷制备的1'α-苯基硒基2'-酮尿苷衍生物6,将其异头Se-C键还原性裂解,生成相应的烯醇sa。与醛如PhCHO,MeCHO,i-PrCHO或(CH(2)O)(n)()高度立体选择性缩合,得到相应的1'alpha-1''S支链产物12a-d。这是第一次通过还原性裂解C-Se键生成烯醇盐。高度选择性的立体化学结果表明,羟醛反应通过螯合控制的过渡态进行。当使用过量的醛并逐渐加热反应混合物时,进行串联的羟醛-季申科反应以得到具有2'-“上位”羟基和1'alpha-1的“阿拉伯型”核苷14a-c。 ''S支链。从醛醇缩合反应产物10合成了1'α-羟甲基尿苷(21),它是抗肿瘤抗生素阿古