Triphenylphosphine → 4-(2-Ethoxy-vinyl)-2-methylsulfanyl-pyrimidine

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Reaction Conditions

Reaction Steps

Ethyl ethynyl ether (2.50 g, 35.7 mmol) was dissolved in 50 mL anhydrous THF under N2. The solution was cooled to 0° C. and BH3-THF (1.0 M in THF, 11.9 mL, 11.9 mmol) was added drop-wise. The reaction was allowed to warm to RT and after 2 h the tris-(2-ethoxy-vinyl)borane that was generated was used in the next step. A flame dried flask under N2 was charged with 4-chloro-2-(methylthio)pyrimidine (0.200 g, 1.25 mmol), Pd(OAc)2 (0.003 g, 0.01 mmol), PPh3 (0.010 g, 0.040 mmol), NaOH (0.149 g, 3.73 mmol). Anhydrous THF, 2 mL, was added followed by the addition of 0.700 mL (0.50 mmol) of the solution of tris-(2-ethoxy-vinyl)borane generated above. The reaction was heated at reflux for 16 h, then was cooled to RT and quenched with sat NaHCO3 (aq). The mixture was extracted 3× with EtOAc and the combined organic extracts were dried over Na2SO4, filtered and concentrated. The product was purified to moderate purity by flash column chromatography and used in the next step.

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