4-Chlorophenyl Isocyanate → N-[[(4-chlorophenyl)amino]carbonyl]-2-benzofuransulfonamide

Participants

Reaction Steps

To a solution of benzofuran (4.55 g, 38.5 mmol) in 100 mL of anhydrous tetrahydrofuran under a nitrogen atmosphere at -78° C. was added a 1.3 M hexanes solution of n-butyllithium (29.6 mL, 38.5 mmol). The reaction was warmed to 0° C. and stirred for 30 minutes. Sulfur dioxide gas was bubbled through this mixture for 20 minutes at 0° C. and the reaction was concentrated under vacuum. The residue was dissolved in 100 mL of water, to which were added 304 millimoles of sodium acetate and 100 millimoles of hydroxylamine-0-sulphonic acid. This reaction was stirred at room temperature for 1.5 hours. The mixture was diluted with 200 mL of water, and the aqueous layer was separated and poured into 600 mL of diethyl ether. The ether layer was extracted with 1 N sodium hydroxide (3×100 mL). The combined aqueous extract was acidified with about 300 mL of 1 N hydrochloric acid, and then extracted with methylene chloride. The combined methylene chloride extract was dried with anhydrous sodium sulfate, filtered, and concentrated under vacuum to provide 2.3 g of 2benzofuransulfonamide. The sulfonamide (11.7 mmol) was reacted with 4-chlorophenylisocyanate (11.7 mmol) as described in Method A above to obtain 2 grams of the title product as a solid. 1H NMR (CD3SOCD3); δ9.23 (s, 1 H), 7.87 (d, J=9 Hz, 1 H), 7.82 (s, 1 H), 7.78 (d, J=9 Hz, 1 H), 7.58 (dd, J=9, 9 Hz, 1 H), 7.46 (m, 1 H), 7.44 (d, J=9 Hz, 2 H), 7.32 (d, J=9 Hz, 2 H).

Provenance & Evidence