To obtain the new compound useful as a fluorescent labeling agent.
This compound of formula I (R is H, a lower alkylamino), e.g. 6-dimethylamlno-2-[4-(N-acryloyl)amino]phenylbenzofuran. The compound of formula I is obtained by reacting a compound of formula II with a compound of formula III (L is a releasable group) in a solvent (e.g. methylene chloride), if necessary, in the presence of a base (e.g. sodium blcarbonate) at -20°C to the boiling point of the solvent. The compound of formula III is used in an amount of 1-2 moles, preferably at least 1 mole, per mole of the compound of formula II. The compound of formula I is stable, does not emit fluorescent light by itself, reacts with a thiol compound to produce the adduct having a strong fluorescent light intensity, and does not by-produce a geometrical isomer and/or an optical isomer on the reaction. The compound is especially useful as a fluorescent labeling agent for highly sensitively determining a thiol compound in a biological specimen.
KAWAI SHINJI
ENDO TAKESHI
