2,2,6,6-Tetramethylpiperidine → 2-Fluoro-3-(tributylstannyl)pyrazine

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium (1.6 M in hexane, 0.920 mL, 10.99 mmol) was added to 2,2,6,6-tetramethylpiperidine (2.024 mL, 11.99 mmol) in THF (50 mL) at −50° C. Following the addition, the mixture was stirred at 0° C. for 20 min and then cooled down to −100° C. 2-Fluoropyrazine (980 mg, 9.99 mmol) in THF (5 mL) was then added dropwisely. After 5 min, tributyltin chloride (3.25 mL, 11.99 mmol) in THF (5 mL) was added dropwisely and stirring was continued for 1 h. The reaction was quenched with a solution of 35% aqueous HCl, ethanol, THF (1:4:5) and allowed to warm to 20° C. The reaction mixture was diluted with sat. aqueous NaHCO3 (30 mL) and extracted with EtOAc (2×50 mL). The organic extract was washed with saturated aqueous NaCl (30 mL) and dried over Na2SO4. The solution was filtered and concentrated in vacuo to give the crude material as orange oil. The crude material was adsorbed onto a plug of silica gel and purified by chromatography through a silica gel column eluting with 50% CH2Cl2/hexanes to give 2-fluoro-3-(tributylstannyl)pyrazine (2980 mg, 7.70 mmol, 77% yield) as colorless oil. 1H NMR (300 MHz, CDCl3) δ 8.63 (s, 1H); 8.02 (s, 1H); 1.46-1.68 (m, 6H); 1.12-1.42 (m, 12H); 0.88 (t, J=7.23 Hz, 9H).

Provenance & Evidence