Citric Acid → Fmoc-Ala-Lys(Mtr)

Participants

Reaction Steps

A solution of Fmoc-Ala-OSu 7c (15.31 mmol) in DME (100 mL) was added to a stirred solution of Lys(Mtr) 2 (6.4080 g, 1 equiv) and potassium bicarbonate (1.5331 mg, 1 equiv) in 2:1 water/DME (150 mL). After 16 h the DME was removed in vacuo and the resulting suspension was treated with citric acid (3.22 g, 1.1 equiv) in water (25 mL). The mixture was extracted with ethyl acetate. The organic phase was washed with water (2×) and brine, dried over sodium sulfate, and concentrated in vacuo, giving a yellow foam which was carried on without further purification. 1H-NMR (CDCl3/CD3OD) δ 1.25 (m, 2H), 1.32 (d, 3H), 1.57 (m, 3H), 1.73 (m, 1H), 2.41 (brt, 2H), 3.72 (s, 3H), 4.14 (m, 1H), 4.29 (m, 4H), 6.79 (d, 2H), 7.22 (m, 16H), 7.38 (d, 4H), 7.52 (m, 2H), 7.72 (d, 2H). MS (FAB) 712.2 (MH)+, 750.2 (M+K)+.

Provenance & Evidence