Trifluoromethanesulfonic anhydride → 1-(tert-Butyl) 3-ethyl 4-(((trifluoromethyl)sulfonyl)oxy)-5,6-dihydropyridine-1,3(2H)-dicarboxylate

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Reaction Steps

Trifluoromethanesulfonic anhydride (15.5 mL, 92.0 mmol) was added over approximately 0.1 h, via syringe, to a stirred solution of the product of step B (33.8 g, 84.0 mmol) and N,N-diisopropylethylamine (17.6 mL, 101.0 mmol) in methylene chloride (300 mL) at −78° C. After allowing to warm to ambient temperature overnight, the reaction mixture was quenched with saturated aqueous sodium bicarbonate, poured into water and extracted three times with methylene chloride. The combined organic extracts were washed with brine, dried (MgSO4) and concentrated in vacuo. Purification of the residue by flash chromatography on silica gel (gradient elution; 0–20% ethyl acetate/hexanes as eluent) gave the title compound as an amber colored oil (23.0 g).

Provenance & Evidence