Dimethyl Sulfoxide → (3S,6S,10aS)-6-tert-butoxycarbonylamino-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

5-Allyl-1-(2-tert-butoxycarbonylamino-pent-4-enoyl)-pyrrolidine-2-carboxylic acid methyl ester, 6, (3.2 g, 8.7 mmol) is dissolved in dichloromethane (40 mL). Grubbs catalyst (0.7 g, 0.85 mmol) is added and the mixture heated to reflux for 4 hours. The reaction is allowed to cool and methylsulfoxide (2 mL) is added. After 2 hours the solution is reduced to a oil, which is purified over silica (50% ethyl acetate hexane) to afford 1.76 g (60% yield) of the desired product as a dark yellow oil. 1H-NMR (300 MHz, CDCl3): δ 5.79 (m, 2H), 5.61 (d, J=6.9, 1H), 4.89 (dd, J=15, 7.2, 5.79 (m, 2H), 5.61 (d, J=6.9, 1H), 4.89 (dd, J=15, 7.2, 5.79 (m, 2H), 5.61 (d, J=6.9, 1H), 4.89 (dd, J=15, 7.2, 1H), 4.54 (m, 1H), 4.15 (m, 1H), 3.75 (s, 3H), 2.81 (m, 2H) 2.49–1.98 (m, 6H), 1.47 (s, 9H). 13C NMR (CDCl3): □ 172.6, 171.3, 155.4, 129.4, 126.0, 79.9, 60.3, 58.9, 52.2, 52.1, 35.5, 33.2, 33.1, 28.6, 27.4. ESI MS: 339.18 (M+H).

Provenance & Evidence