[CH3:1][O:2][C:3]1[C:8]([O:9][CH3:10])=[CH:7][C:6]([C:11]#[C:12][Si](C)(C)C)=[CH:5][N:4]=1.[OH-].[Na+]>CO>[C:11]([C:6]1[CH:7]=[C:8]([O:9][CH3:10])[C:3]([O:2][CH3:1])=[N:4][CH:5]=1)#[CH:12]2,3-Dimethoxy-5-[(trimethylsilyl)ethynyl]pyridine (Intermediate 31) (9.8 g, 42 mmol) was dissolved in a mixture of aqueous sodium hydroxide (21 ml, 2 M, 42 mmol) and methanol (50 ml) to give a colourless solution which was stirred for 16 hours. The reaction was evaporated and the residue was partitioned between ethyl acetate and water before the organic layer was dried and concentrated in vacuo. The crude material was purified by (SiO2; 0-10% ethyl acetate in petrol) to afford 5-ethynyl-2,3-dimethoxypyridine (5.6 g, 82%).
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