3-Chlorobenzoic Acid → 4-chloro-N-[5-chloro-2-(7-chloro-3-oxo-1,3-dihydro-isobenzofuran-1-yl)-pyridin-3-yl]-N-methoxymethyl-3-trifluoromethyl-benzene-sulfonamide

Participants

Reaction Conditions

Reaction Steps

To a solution of n-BuLi in hexane (0.69 mL, 1.1 mmol, 1.6 M solution in hexane) under N2 atm at −20° C. was added a solution of 2,2,6,6-tetramethyl piperidine (TMP, 187 μL) in THF (1 mL). The mixture cooled to −50° C. and a solution of 3-chlorobenzoic acid (78.3 mg, 0.5 mmol) in THF (0.5 mL) was added. The resulting reaction mixture was stirred at −50° C. for 4 h and treated slowly with 4-chloro-N-(5-chloro-2-formyl-pyridin-3-yl)-N-methoxymethyl-3-trifluoromethyl-benzenesulfonamide (884 mg, 2.0 mmol) in THF (1 mL), warmed to room temperature and stirred for 2 h. The reaction mixture was slowly poured in ice cold water (10 mL), and ether was added. The bilayer was separated and the aqueous portion was washed with diethyl ether (2×25 mL) and separated. The aqueous layer was acidified with 4 N HCl solutions to pH 2 and extracted with diethyl ether (2×25 mL). The combined organic extracts were dried (Na2SO4), filtered and evaporated. The residual solid was dissolved in CH2Cl2 (5 mL), treated with p-toluenesulfonic acid monohydrate (100 mg), and stirred at room temperature for 2 h. The reaction mixture was concentrated and purified by flash chromatography (25% EtOAc in hexanes) to obtain 4-chloro-N-[5-chloro-2-(7-chloro-3-oxo-1,3-dihydro-isobenzofuran-1-yl)-pyridin-3-yl]-N-methoxymethyl-3-trifluoromethyl-benzenesulfonamide (77 mg) in 26.6% yield. MS m/z: 581 (M+H).

Provenance & Evidence