6-Tert-butoxycarbonylamino-5-oxo-1,2,3,5,6,7,10,10a-octahydro-pyrrolo[1,2-a]azocine-3-carboxylic acid methyl ester → (3S,6S,10aS)-6-amino-5-oxo-1,2,3,5,6,7,10,10a-octahydro-pyrrolo[1,2-a]azocine-3-carboxylic acid methyl ester

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Reaction Steps

6-tert-butoxycarbonylamino-5-oxo-1,2,3,5,6,7,10,10a-octahydro-pyrrolo[1,2-a]azocine-3-carboxylic acid methyl ester, 7, (3.46 g, 10.2 mmol) is treated with a solution of 1:1 trifluoroacetic acid/CH2Cl2 (50 mL) and allowed to stir for 2 hours at room temperature after which the solution is concentrated in vacuo and the resulting residue purified over silica (5% methanol/methylene chloride) to afford 2.43 g (100% yield) of the desired product as dark orange crystals. 1H NMR (CDCl3): δ 8.11 (bs, 2H), 5.76 (m, 2H), 4.66 (dd, J=9.3, 6.0 Hz, 1H), 4.50 (dd, J=8.7, 3.6, 1H), 4.21 (m, 1H), 3.68 (s, 3H), 2.95 (m, 1H), 2.73 (dt, J=15.3, 6.0, 1H), 2.43 (m, 2H), 2.15 (m, 2H), 1.94 (m, 2H). 13C NMR (CDCl3): δ 172.3, 168.5, 127.1, 60.7, 58.7, 52.3, 51.9, 32.7, 32.6, 31.2, 27.3. ESI MS 239.12 (M+H).

Provenance & Evidence