反应详情

To a solution of tert-butyl 3-oxocyclopentanecarboxylate (19.8 g, 107 mmol) in 1:1 DCM/methanol (150 mL) was added trimethylorthoformate (46.8 mL, 428 mmol), followed by TsOH.H2O (˜0.5 g). The reaction mixture was stirred at rt for 2 h. Then more TsOH.H2O (˜0.25 g) was added and the reaction mixture was stirred overnight. The reaction mixture was concentrated at rt and the resulting residue was dissolved in ether and washed with saturated NaHCO3 solution, then with brine. The ethereal layer was dried over anhydrous MgSO4, filtered, and concentrated. Purification by flash chromatography (silica, 15% ethyl acetate/hexane) gave tert-butyl 3,3-dimethoxycyclopentanecarboxylate. 1H NMR (500 MHz, CDCl3): 3.21 (s, 3H), 3.20 (s, 3H), 2.80 (m, 1H), 2.10 to 1.80 (bm, 6H), 1.46 (s, 9H). 13C NMR (125 MHz, CDCl3): 174.9, 111.2, 80.3, 67.8, 49.2, 42.5, 37.4, 33.8, 28.3, 22.0.

1. stirringthe reaction mixture was stirred overnight
2. concentrationThe reaction mixture was concentrated at rt
3. dissolutionthe resulting residue was dissolved in ether
4. washwashed with saturated NaHCO3 solution
5. dry with materialThe ethereal layer was dried over anhydrous MgSO4
6. filtrationfiltered
7. concentrationconcentrated
8. customPurification by flash chromatography (silica, 15% ethyl acetate/hexane)