[OH:1][CH2:2][C:3]([CH3:12])([CH3:11])[C:4]([O:6][C:7]([CH3:10])([CH3:9])[CH3:8])=[O:5].CS(O[CH2:18][CH2:19][O:20][CH2:21][CH2:22][O:23][CH2:24][C:25]1[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1)(=O)=O.[H-].[Na+]>CN(C=O)C>[CH2:24]([O:23][CH2:22][CH2:21][O:20][CH2:19][CH2:18][O:1][CH2:2][C:3]([CH3:12])([CH3:11])[C:4]([O:6][C:7]([CH3:10])([CH3:9])[CH3:8])=[O:5])[C:25]1[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1To a solution of tert-butyl 3-hydroxy-2,2-dimethylpropanoate (353 mg, 2.03 mmol) and 2-(2-(benzyloxy)ethoxy)ethyl methanesulfonate (47) (500 mg, 1.82 mmol) in DMF (6 mL) at 0° C. was added NaH (60 wt % in oil) (109 mg, 2.73 mmol), and the reaction mixture was allowed to stir at RT for 30 min. The reaction mixture was quenched with sat. NH4Cl (aq.) (1 mL) diluted with water (20 mL) and washed with EtOAc (4×20 mL). The combined organic layers were dried (MgSO4), filtered and concentrated in vacuo. The crude product was purified by silica gel chromatography (12 g, 0-40% Et2O in isohexane) to afford tert-butyl 3-(2-(2-(benzyloxy)ethoxy)ethoxy)-2,2-dimethylpropanoate (48) (619 mg, 96%) as a colourless oil: m/z 375 (M+Na)+ (ES+). 1H NMR (400 MHz, CDCl3) δ: 7.32-7.25 (m, 5H), 4.54 (s, 2H), 3.66-3.56 (m, 8H), 3.41 (s, 2H), 1.40 (s, 8H), 1.10 (s, 6H).
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