Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences & IOCB Research Center, Flemingovo nam. 2, CZ-16610 Prague 6, Czech Republic.
J Org Chem. 2011 Jul 1;76(13):5309-19. doi: 10.1021/jo2006494. Epub 2011 May 26.
A new regioselective synthesis of 5- and 6-aryluracil bases based on direct C-H arylations of diverse 1,3-protected uracils has been developed. Benzyl-protected uracils were selected as the most practical in terms of stability during the arylation and facile cleavage of the benzyl groups. Pd-catalyzed C-H arylations in the absence of CuI gave preferentially 5-aryl-, whereas the reactions in the presence of CuI gave 6-aryl-1,3-dibenzyluracils. Final deprotection either by transfer hydrogenolysis over Pd/C or by treatment with BBr(3) gave the desired free arylated uracil bases in good yields.
已经开发出一种新的基于各种 1,3-保护尿嘧啶的直接 C-H 芳基化反应的 5-和 6-芳基尿嘧啶碱基的区域选择性合成方法。在芳基化过程中以及苄基基团的易于裂解方面，苄基保护的尿嘧啶被选择为最实用的。在不存在 CuI 的情况下，Pd 催化的 C-H 芳基化反应优先得到 5-芳基产物，而在存在 CuI 的情况下，反应得到 6-芳基-1,3-二苄基尿嘧啶。最终通过 Pd/C 上的转移氢化或用 BBr(3)处理进行脱保护，以良好的收率得到所需的游离芳基化尿嘧啶碱基。
