Triethylamine → 2-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

The starting amine (5) (0.15 g, 0.12 mmol) and fluorescein isothiocyanate (FLITC) (0.056 g, 0.14 mmol) were dissolved in a mixture of DMF and CH2Cl2 (6 mL, 1:5 ratio) at room temperature. The reaction was cooled to 0° C., and then an excess amount of Et3N (66 μL, 0.48 mmol) was added dropwise. An orange colored precipitate was immediately formed and remained during the entire period of the reaction. After completion of the reaction, the insoluble precipitate was filtered off; and the solvent was removed under reduced pressure. The residue was diluted with CH2Cl2 (15 mL), washed with 1N HCl (2×15 mL) and H2O (2×15 mL). The organic phase was dried over anhydrous Na2SO4 and evaporated under reduced pressure to afford 0.18 g (92%) of fluorescein-labeled guanidine (17) as an orange colored foam-shaped solid. 1H NMR (CD3OD): δ 8.20 (s, 1H, ArH), 7.86 (m, 1H, ArH), 7.22 (m, 2H, ArH), 6.64 (m, 3H, ArH), 6.56 (m, 2H, ArH), 3.86 (m, 2H, CH2NHCS), 3.66 (m, 12H, CH2O), 3.46 (m, 6H, CH2NHCO), 3.38 (m, 6H, CH2NH), 2.58 (m, 2H, CH2CO), 2.42 (m, 6H, CH2CO), 1.48 (s, 27H, t-Bu), 1.46 (s, 27H, t-Bu).

Provenance & Evidence