[C:1]1([C:7]#[CH:8])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[Li]CCCC.[CH3:14][O:15][C:16]1[C:21]([CH:22]=[O:23])=[CH:20][CH:19]=[C:18]([O:24][CH3:25])[N:17]=1.[Cl-].[NH4+]>C1COCC1>[CH3:14][O:15][C:16]1[C:21]([CH:22]([OH:23])[C:8]#[C:7][C:1]2[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=2)=[CH:20][CH:19]=[C:18]([O:24][CH3:25])[N:17]=1
To a solution of phenylacetylene (0.61 g, 5.98 mmol) in dry THF (10 mL), cooled to −78° C., was added 2.5 M nBuLi in hexanes (2.4 mL, 6.0 mmol). The mixture was stirred for 15 min at −78° C., followed by addition of a solution of 2,6-dimethoxypyridine-3-carbaldehyde (1.0 g, 6.0 mmol) in THF (10 mL) was added over 5 minutes. The reaction mixture was allowed to warm to 0° C. and saturated ammonium chloride was added. The resultant biphasic mixture was separated and extracted twice with ethyl acetate. The combined organic phase was washed with brine, dried (Na2SO4), filtered and concentrated in vacuo. The resultant residue was subjected to flash chromatography (SiO2, gradient 10 to 30% ethyl acetate in cyclohexane) to afford the title compound (1.60 g, 99%) as a colourless gum. LCMS (Method B): RT=4.38 min, [M+H]+=270.
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