Hexane → 5-Chloropyridin-3-yl trifluoromethanesulfonate

Participants

Reaction Conditions

Reaction Steps

Trifluoromethanesulfonic anhydride (5.0 mL, 30 mmol) was dissolved in CH2Cl2 (100 mL), and cooled to 0° C. 5-Chloro-3-pyridinol (3.10 g, 23.9 mmol), and triethylamine (6.5 mL, 47 mmol) were dissolved in CH2Cl2 (50 mL), and the resulting solution was added to the cold trifluoromethanesulfonic anhydride solution dropwise via cannula. The resulting dark brownish-red solution was stirred at 0° C. for 5 minutes, and then the ice bath was removed and the reaction mixture was allowed to warm to ambient temperature. After stirring for 16 h at ambient temperature the reaction was quenched by pouring into water and basified by addition of saturated aqueous sodium carbonate. The basic aqueous phase was extracted with CH2Cl2 (2×50 mL), the combined organics dried over Na2SO4, filtered and concentrated in vacuo. The resulting black viscous oil was filtered through a plug of silica gel and fractions were collected while eluting with 1:1 hexane:ethyl acetate. Fractions containing the desired product were combined, concentrated in vacuo, and further purified by column chromatography eluting with 15:1 then 10:1 hexane:ethyl acetate to afford 5-chloro-3-pyridinyl trifluoromethanesulfonate (3.68 g, 59% yield) as a golden liquid. 1H NMR (CDCl3, 300 MHz) δ 8.65 (d, J=2 Hz, 1H), 8.52 (d, J=2 Hz, 1H), 7.70 (t, J=3 Hz, 1H). MS (ESI) 261 (M+, 35Cl), 263 (M+, 37Cl).

Provenance & Evidence