Jiao Guan-Sheng, Han Jin Wook, Burgess Kevin
Department of Chemistry, Texas A & M University, Box 30012, College Station, Texas 77842-3012, USA.
J Org Chem. 2003 Oct 17;68(21):8264-7. doi: 10.1021/jo034724f.
Three routes to regioisomerically pure 5- and 6-iodofluoresceins or 5- and 6-bromofluoresceins are described. The first, shown in Scheme 1, involves diazotization/iodination of the corresponding aminofluoresceins. In the second approach (Scheme 2) a mixture of regioisomeric fluoresceins was prepared, and the 5-bromo isomers were isolated as the ring closed diacetates 9b and 11 by fractional crystallization. Scheme 3 shows an approach to sulfonic acid derivatives 3 and 4 of 5-iodofluorescein. This is the most convenient procedure of the three, and it is particularly useful as sulfofluoresceins have more favorable water solubility characteristics than fluoresceins that lack the sulfonic acid group.
描述了制备区域异构体纯的5-和6-碘荧光素或5-和6-溴荧光素的三种方法。第一种方法如图1所示，涉及相应氨基荧光素的重氮化/碘化反应。第二种方法（图2）是制备区域异构体荧光素的混合物，通过分步结晶将5-溴异构体分离为闭环二乙酸酯9b和11。图3展示了一种制备5-碘荧光素磺酸衍生物3和4的方法。这是三种方法中最简便的一种，特别有用，因为磺酸荧光素比不含磺酸基团的荧光素具有更良好的水溶性特征。
