Syntheses of regioisomerically pure 5- or 6-halogenated fluoresceins.
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.
Jiao
Guan-Sheng
GS
Department of Chemistry, Texas A & M University, Box 30012, College Station, Texas 77842-3012, USA.
Han
Jin Wook
JW
Burgess
Kevin
K
D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006846:Hydrocarbons, Halogenated / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D005452:Fluoresceins; D005456:Fluorescent Dyes; D006846:Hydrocarbons, Halogenated