(S)-tert-Butyl 2-((tert-butoxycarbonyl)amino)-5-(4-methoxy-7-nitroindolin-1-yl)-5-oxopentanoate is an intermediate in the synthesis of MNI-caged-L-glutamate, which is a new caged neuroactive amino acid, that use 4-methoxy-7-nitroindolinyl- (MNI) group to make caged ligands specific for glutamate receptor sub-types. MNI-caged-L-glutamate, rapidly release glutamate when photolysed.