反应详情

To a solution of 2-tert-butyl 2-ethyl 5-oxohexahydropentalene-2,2(1H)-dicarboxylate (0.8 g, 2.70 mmol) in DCM (4 mL) was added TFA (2.080 mL) and the reaction mixture was stirred at rt for 4 h. The reaction mixture was evaporated to dryness and the residue was dissolved in pyridine (5 mL) and heated to reflux for 4 h until decarboxylation was complete. Pyridine was evaporated and the residue was purified by silica gel chromatography (10% EtOAC in DCM) to afford ethyl 5-oxooctahydropentalene-2-carboxylate (a mixture of endo/exo isomers) as a clear oil. 1H NMR (500 MHz, CDCl3) δ ppm 4.10-4.18 (2H, m), 2.85-3.02 (2H, m), 2.69-2.80 (1H, m), 2.44-2.56 (2H, m), 2.20-2.36 (2H, m), 2.10-2.20 (1H, m), 2.04 (1H, dd, J=19.45, 4.65 Hz), 1.66-1.80 (2H, m), 1.22-1.31 (3H, m).

1. customThe reaction mixture was evaporated to dryness
2. dissolutionthe residue was dissolved in pyridine (5 mL)
3. temperatureheated
4. temperatureto reflux for 4 h until decarboxylation
5. customPyridine was evaporated
6. customthe residue was purified by silica gel chromatography (10% EtOAC in DCM)