2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 2-Chloro-4-(5-tosylthiophen-2-yl)pyrimidine

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium in hexanes (0.92 mL, 2.5 M, 2.30 mmol) was added dropwise to a solution of 2-tosylthiophene (0.5 g, 2.09 mmol) in anhydrous tetrahydrofuran (30 mL) at −78° C. The resulting mixture was stirred at −78° C. for 1 h and a solution of 2-chloropyrimidine (0.26 g, 2.30 mmol) in 3 mL of tetrahydrofuran was added slowly. The mixture was stirred at −78° C. for 1 h and then at −40° C. for 2 h. The reaction was quenched with a solution (0.22 mL) of acetic acid and methanol (1:1) at −40° C. and a solution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (0.57 g, 2.51 mmol) was added. After complete addition the reaction was stirred for 1 h, and then warmed to rt and stirred for an additional 15 h. 20 mL of aqueous sodium hydroxide (2 M) was added and the mixture was extracted with ethyl acetate (3×50 mL). The combined organic layer was washed with brine (80 mL), dried over anhydrous sodium sulfate and filtered. The solvent was evaporated in vacuo and the product was purified by flash chromatography eluting with ethyl acetate/hexane (1:3) to afford the title compound as a white solid (0.36 g, 49%).

Provenance & Evidence