L-Lysine → Ninhydrin

Participants

Reaction Steps

To a stirred solution of diallyl glutamate (3.96 g, 15 mmol) and triphosgene (1.47 g, 4.95 mmol) in CH2Cl2 (143 mL) at −78° C. was added Et3N (6.4 mL, 46 mmol) in CH2Cl2 (28 mL). The reaction mixture was allowed to warm to room temperature and stirred for 1.5 h. The Lysine derivative (2.6 g, 9.09 mmol) in a solution of CH2Cl2 (36 mL) was then added at −78° C. and the reaction was stirred at room temperature for 12 h. The solution was diluted with CH2Cl2, washed twice with H2O, dried over MgSO4 (anh.) and purified by column chromatography (Hexane:AcOEt 3:1→2:1→AcOEt) to give 4 g (82%) (TLC in CH2Cl2:MeOH 20:1 Rf=0.3, revealed with ninhydrin). 1H-NMR (CDCl3, 300 MHz) δ 5.97-5.84 (m, 3H, 3-CH2CHCH2), 5.50 (bt, 2H, 2NHurea), 5.36-5.20 (m, 6H, 3-CH2CHCH2), 4.81 (bs, 1H, NHBoc), 4.68-4.40 (m, 8H, 3-CH2CHCH2, CH(Lys), CH(glu)), 3.09-3.05 (m, 2H, CH2NHBoc), 2.52-2.39 (m, 2H, CH2(glu.)), 2.25-2.14 and 2.02-1.92 (2m, 2H, CH2(glu.)), 1.87-1.64 (m, 4H, 2CH2(Lys)), 1.51-1.35 (m, 2H, CH2(Lys)), 1.44 (s, 9H, Boc).

Provenance & Evidence