[Br:1][C:2]1[N:7]=[CH:6][C:5](I)=[CH:4][N:3]=1.[C:9]([Si:11]([CH3:14])([CH3:13])[CH3:12])#[CH:10].C(N(CC)CC)C>C1COCC1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.Cl[Pd]Cl.[Cu]I>[Br:1][C:2]1[N:7]=[CH:6][C:5]([C:10]#[C:9][Si:11]([CH3:14])([CH3:13])[CH3:12])=[CH:4][N:3]=1
2-Bromo-5-iodopyrimidine (1.2 g, 4.2 mmol) was dissolved under nitrogen in 25 ml THF. Bis-(triphenylphosphine)-palladium(II)dichloride (300 mg, 420 μmol, 0.1 equiv.), ethynyltrimethylsilane (540 mg, 0.77 ml, 5.48 mmol, 1.3 equiv.), triethylamine (0.85 g, 1.17 ml, 8.4 mmol, 2 equiv.) and copper(I)iodide (40 mg, 210 μmol, 0.05 equiv.) were added and the mixture was stirred for 4 hours at 50° C. The reaction mixture was cooled and evaporated to dryness. The crude product was purified by flash chromatography on silica gel, eluting with an ethyl acetate:heptane gradient 0:100 to 40:60. The desired 2-bromo-5-trimethylsilanylethynyl-pyrimidine (0.75 g, 70% yield) was obtained as a yellow solid, MS: m/e=255/257 (M+H+).
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