Mild synthesis of asymmetric 2'-carboxyethyl-substituted fluoresceins.
Asymmetric fluoresceins bearing a carboxyethyl group in the chromophoric portion of the dyes were prepared by a reaction of substituted phthalic anhydride with a carboxyethyl substituted resorcinol analogue followed by a condensation with a second resorcinol analogue. In order to avoid an accumulation of symmetric side products, the second step was performed in two substeps: acid-catalyzed formation of a triphenylmethyl intermediate followed by base-catalyzed cyclization which furnished the desired dyes.
Lukhtanov
Eugeny A
EA
Nanogen Inc., 21720 23rd Drive SE, Suite 150, Bothell, Washington 98021, USA. elukhtanov@nanogen.com
Vorobiev
Alexei V
AV