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NMR (75 MHz, CDCl3): δ 172.3, 169.7, 137.7, 137.3, 137.2, 135.4, 131.1, 129.5, 128.3, 128.1,
126.7, 126.4, 122.0, 101.2, 73.1, 62.3, 56.4, 52.6, 52.0, 47.1, 45.7, 39.1, 29.4, 29.0, 22.3, 14.1;
IR (thin film): ν 3418, 2928, 1732, 1622, 1405, 1259 cm -1 ; MS m/z (%) 486 (26), 395 (30), 105
(76), 57 (100). EI-HRMS calcd for C30H34N2O4 m/z [M] + 486.2519; found 486.2510.
General procedure S for the Stetter reaction with glyoxylamides.
BzN O
MeO2C Bn
H O
2-Benzoyl-1-benzyl-6-(2,3-dioxo-3-pyrrolidin-1-ylpropyl)-5-oxo-1,2,3,5,6,6a-
305
hexahydrocyclopenta[c]pyrrole-1-carboxylic acid methyl ester (305). To a solution of 287b
(840 mg, 2.17 mmol) in 1,4-dioxane (20 mL) was added oxo-pyrrolidin-1-yl-acetaldehyde 303 mm
(1.38 g, 11.8 mmol), 292 (175 mg, 0.651 mmol) and Et3N (905 µL, 6.51 mmol). The reaction
mixture was heated to 70 °C for 10 min and then poured in water (200 mL). The aqueous layer
was extracted with Et2O (3 x 100 mL) and the extracts were combined, washed with brine, dried
over MgSO4 and concentrated under vacuum. The crude residue was purified by flash
chromatography (gradient elution; hexanes-EtOAc, 3 : 1 to 0 : 1, v/v) to give 305 (1.17 g,
>95%).
1 H NMR (300 MHz, CDCl3): δ 7.54-7.42 (m, 5H), 7.36-7.29 (m, 3H), 7.23-7.20 (m, 2H), 5.91 (s,
1H), 4.27 (d, J = 15.7 Hz, 1H), 4.17 (d, J = 14.3 Hz, 1H), 4.07 (d, J = 15.7 Hz, 1H), 3.82 (s, 3H),
3.66 (t, J = 6.4 Hz, 2H), 3.58 (t, J = 6.4 Hz, 2H), 3.52-3.44 (m, 2H), 3.33 (dd, J = 18.7, 5.3 Hz,
1H), 3.23 (d, J = 14.3 Hz, 1H), 2.47 (q, J = 4.7 Hz, 1H), 1.99-1.90 (m, 4H); 13 C NMR (75 MHz,
mm Aldehydes 302 and 303 was prepared according to previously reported procedures. 208, 209
263
O
N