1-Hydroxybenzotriazole → (4S,7S,11aR)-7-benzoylamino-6-oxo-1,3,4,6,7,8,11,11a-octahydro-2H-pyrido[1,2-a]azocine-4-carboxylic Acid

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Reaction Steps

Preparation of (4S,7S,11aR)-7-benzoylamino-6-oxo-1,3,4,6,7,8,11,11a-octahydro-2H-pyrido[1,2-a]azocine-4-carboxylic acid (2-ethoxy-5-oxo-tetrahydro-furan-3-yl)-amide (45) A catalytic amount of Pd(Ph3P)4 (35 mg, 0.03 mmol) is added to a solution of (2-Ethoxy-5-oxo-tetrahydrofuran-3-yl)-carbamic acid allyl ester (69 mg, 0.3 mmol) and N,N-dimethylbarbituric acid (156 mg, 1.0 mmol) in 2 mL CH2Cl2 at room temperature. The solution is stirred at rt for 15 minutes and (4S,7S,11aS)-7-benzoylamino-6-oxo-1,3,4,6,7,8,11,11a-octahydro-2H-pyrido[1,2-a]azocine-4-carboxylic acid, 44, (40 mg, 0.12 mmol) is added as a solution in 1 mL CH2Cl2, followed by 1-hydroxybenzotriazole (41 mg, 0.3 mmol) and 1-(3-dimethyl-aminopropyl)-3-ethyl-carbodiimide hydrochloride (58 mg, 0.3 mmol). The solution is stirred for 4 hours, diluted with EtOAc, washed with saturated NaHCO3 and brine, dried (MgSO4), and concentrated in vacuo. Purification by flash chromatography over silica gel afforded 32 mg of the desired product. 1H NMR (CDCl3) δ 7.88 (m, 2H), 7.72 (m, 1H), 7.51 (m, 3H), 5.75–5.25 (series of m, 4H), 5.02 (d, J=5.8 Hz, 1H), 4.66 (m, 2H), 3.98 (dq, J=9.3, 7.0 Hz, 1H), 3.73 (dq, J=9.3, 7.0 Hz, 1H), 3.24 (m, 1H), 2.96–1.45 (series of m, 11H), 1.37 (t, J=7.0 Hz, 3H); MS 470 (M+H)+.

Provenance & Evidence