4-Methylmorpholine → Ampicillin

Participants

Reaction Steps

To a solution of acid 9 (22 mg, 0.023 mmol) and N-methyl morpholine (2.5 μL, 0.023 mmol) in 1 mL of anhydrous THF cooled to 0° C. was added isobutyl chloroformate (3.0 μL, 0.023 mmol) and the mixture was stirred for 1 hour at that temperature. A solution of ampicillin trihydrate (10.6 mg, 0.026 mmol) and Et3N (10 μL) in 1 mL of THF/H2O 4:1 was added and the mixture was stirred for 1 h at 0° C. and 1 h at room temperature. After removal of the THF under vacuum, the residue was dissolved in 5 mL of water and the solution was acidified to pH=2 with 1 N HCl. The resulting suspension was extracted with EtOAc (5 mL×3) and the combined organic layers were washed with brine, dried over Na2SO4 and filtered. The solvent was removed under vacuum and the residue was purified by preparative HPLC. The fractions containing product was combined and lyophilized to give conjugate 10 (16.4 mg, 55%) as a white solid: 1H NMR (600 MHz, DMSO-d6) δ9.06 (d, J=7.6 Hz, 1H), 8.54 (d, J=8.5 Hz, 1H), 8.31 (t, J=5.6 Hz, 3H), 7.40-7.44 (m, 5H), 7.24-7.36 (m, 9H), 7.12 (s, 1H), 5.71 (d, J=8.2 Hz, 1H), 5.46 (dd, J=7.9, 4.1 Hz, 1H), 5.35 (d, J=4.1 Hz, 1H), 4.11 (s, 1H), 3.12-3.16 (m, 6H), 2.43-2.45 (m, 2H), 2.30-2.34 (m, 2H), 2.27 (s, 9H), 2.20 (s, 9H), 1.59-1.65 (m, 6H), 1.53 (s, 3H), 1.37-1.43 (m, 9H); HRMS (ESI) calcd. for C63H72N7O21S (M+H)+: 1294.4496, found 1294.4522; HPLC retention time 5.57 min.

Provenance & Evidence