Synthesis and photoreactivity of caged blockers for glutamate transporters

-TBOA ( -threo-β-benzyloxyaspartate) is, so far, the most potent non-transportable blocker for glutamate transporters. We synthesized α-CMCM- -TBOA (1a) possessing [7-(carboxymethoxy)coumarin-4-yl]methyl ester as a caging group. α-CMCM- -TBOA (1a) is biologically inactive until UV irradiation and the photolysis of 1a immediately released -TBOA to show glutamate uptake inhibition. The photoreactivity of the coumarin-type caging group was superior to that of the o-nitrobenzyl-type caging group.