2-(Methylthio)-4-(tributylstannyl)pyrimidine → Methyl-[3-(2-methylsulfanyl-pyrimidin-4-yl)-imidazo[1,2-a]pyrazin-8-yl]-carbamic acid tert-butyl ester

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Reaction Steps

2-Methylsulfanyl-4-tributylstannanyl-pyrimidine (19.1 g, 46.0 mmol) was stirred in degassed toluene (achieved by bubbling nitrogen though solvent for 2 hours) (200 mL) under nitrogen, then (3-bromo-imidazo[1,2-a]pyrazin-8-yl)-methyl-carbamic acid tert-butyl ester (13.1 g, 40.0 mmol) (from Example 7 supra) was added followed by bis(triphenylphosphine)palladium (II) chloride (1.12 g, 1.60 mmol) and the reaction was heated at reflux. The reaction was cooled to room temperature and concentrated to dryness. The residue was purified by column chromatography on silica gel (petroleum ether to EtOAc, TLC Rf=0.17, 20% EtOAc in petroleum ether) and then triturated with DIPE to give methyl-[3-(2-methylsulfanyl-pyrimidin-4-yl)-imidazo[1,2-a]pyrazin-8-yl]-carbamic acid tert-butyl ester. (Yield 8.00 g, 54%).

Provenance & Evidence