[OH:1][C:2]([CH3:8])([CH3:7])[C:3]([O:5][CH3:6])=[O:4].[H-].[Na+].[CH2:11](Br)[C:12]#[CH:13]>CN(C)C=O.C1(C)C=CC=CC=1>[C:11]([O:1][C:2]([CH3:8])([CH3:7])[C:3]([O:5][CH3:6])=[O:4])#[C:12][CH3:13]55 g (0.47 mol) of methyl 2-hydroxy-2-methylpropionate in 400 ml of dry dimethylformamide were added dropwise while stirring during 0.75 hour to 14 g (0.47 mol, 80% oil dispersion) of sodium hydride in 200 ml of dry dimethylformamide. After 3 hours at 20° C. 62.5 g (0.42 mol) of propargyl bromide (as a 80% solution in toluene) in 200 ml of dimethylformamide was added during 0.5 hour while cooling to maintain the temperature below 25° C. After stirring at 20° C. for 17 hours the mixture was poured on to ice and extracted with toluene. The toluene phase was evaporated carefully and the residue was distilled at 80° C./15 mmHg to give 26.8 g (41%) of methyl 2-propynyloxy-2-methylpropionate.
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