| Abstract
| - Three routes to regioisomerically pure 5- and6-iodofluoresceins or 5- and 6-bromofluoresceins are described. The first, shown in Scheme , involves diazotization/iodination of the corresponding aminofluoresceins. In thesecond approach (Scheme ) a mixture of regioisomericfluoresceins was prepared, and the 5-bromo isomers wereisolated as the ring closed diacetates 9b and 11 by fractionalcrystallization. Scheme shows an approach to sulfonic acidderivatives 3 and 4 of 5-iodofluorescein. This is the mostconvenient procedure of the three, and it is particularlyuseful as sulfofluoresceins have more favorable water solubility characteristics than fluoresceins that lack the sulfonicacid group.
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