Synthesis and spectral properties of DEAC450-Glu. (a) Reagents and conditions: (a) tert-Butyldimethylsilylchloride, imidazole. (b) N-bromosuccinimide, NaOAc. (c) tert-Butylacrylic acid, Pd(OAc)2, LiCl, NaHCO3, Bu4NCl. (d) TFA. (e) Di-tert-butylaspartate, EDC. (f) TBAF. (g) tert-Butyl-BOC-L-glutamate, EDC followed by TFA. (b) Absorption spectra of CDNI-Glu (cyan), N-DCAC-GABA (DEAC core in pink) and DEAC450-Glu (red). (c) Absorption spectra of RuBi-Glu (green), ANBP-GABA (orange) and DEAC450-Glu (red).