[CH:1]1([C:5]([O:7][CH2:8][CH3:9])=[O:6])[CH2:4][CH2:3][CH2:2]1.[CH:10]([N-]C(C)C)([CH3:12])[CH3:11].[Li+].ICCC>C1COCC1.CS(C)=O>[CH2:8]([O:7][C:5]([C:1]1([CH2:11][CH2:10][CH3:12])[CH2:4][CH2:3][CH2:2]1)=[O:6])[CH3:9]Ethyl cyclobutanecarboxylate 1 (25.0 g, 0.195 mol) was added to a solution of lithium diisopropylamide (97.5 mL of a 2.0M solution in THF, 0.195 mol) in THF (200 mL) at −78° C. After 30 min the reaction solution was warmed to room temperature and transferred via canula to a solution of 1-iodopropane (49.7 g, 0.293 mol) in DMSO (104 mL) while maintaining the temperature between 15-20° C. After stirring for an additional 30 min the precipitated salts were removed by vacuum filtration. The filtrate was concentrated in vacuo, diluted with hexane and washed with 1N HCl, saturated aqueous NaHCO3 and brine. The organic portion was dried (MgSO4), filtered and concentrated in vacuo. The residue was purified by vacuum distillation (105-108° C., 20-30 mmHg) to give 16 g (48%) of the ester 2 as a clear, colorless oil.
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