Reaction Steps
To a solution of (2-Ethoxy-5-oxo-tetrahydro-furan-3-yl)-carbamic acid allyl ester (183 mg, 0.8 mmol) in dichloromethane (6 mL) is added barbituric acid (300 mg, 1.9 mmol) and tetrakis triphenylphosphine palladium (92 mg, 0.08 mmol). The solution is stirred for 10 minutes and 6-benzoylamino-9-methyl-5-oxo-decahydro-pyrrolo[1,2-a]azocine-3-carboxylic acid, 20, (105 mg, 0.32 mmol) is added followed by HOBt (99 mg, 0.74 mmol) and EDCI (141 mg, 0.74 mmol). The solution is stirred for 6 hours. Water is added and the organics are washed with NaHSO4, Brine, NaHCO3, and water. The organics are dried with MgSO4 and concentrated under reduced pressure. The residue is purified over silica to afford an oil which is dissolved in dichloromethane and treated with TFA (5 mL) and water (1 mL). The solution is stirred for 2 hours and the solvent is removed. The residue is purified over silica to afford the desired product as a white powder. 1H NMR (CDCl3): δ 7.83 (m, 2H), 7.56–7.39 (m, 3H), 7.26 (m, 2H), 5.51 (d, J=5.2, 1H), 5.16 (m,1H), 4.72 (m, 1H), 4.56 (t, J=8.1 Hz, 1H), 4.35 (m, 1H), 3.95 (m, 1H), 3.71 (m, 2H), 2.90 (m, 1H), 2.52–2.38 (m, 2H), 2.26–2.05 (m, 4H), 1.87–1.61 (m, 5H), 1.32 (t, J=6.9 Hz, 3H). 13C NMR (CDCl3): δ 173.7, 172.2, 171.7, 166.6, 131.9, 128.8, 127.3, 101.3, 65.9, 60.8, 59.5, 50.6, 48.6, 36.9, 36.3, 33.1, 32.4, 25.7, 25.6, 23.6, 15.2. ESI MS: 458.16 (M+H), 480.11 (M+Na).
