Hydrochloric Acid → 4-[4-(3-Cyclopentylpropyl)-5-Tetrazolon-1-Yl]-Benzenesulfonyl Chloride

Participants

Reaction Steps

To a solution of 32 mL of concentrated hydrochloric acid and 8 mL of glacial acetic acid at -20° C. was added 5.42 g of powdered 1-(4-aminophenyl)-4-(3-cyclopentylpropyl)-5-tetrazolone from Step D. The mixture was stirred for 5 min before a solution of 1.6 g of sodium nitrite in 10 mL of water was added at a rate which kept the temperature from rising above -10° C. The diazonium salt mixture was stirred an additional 40 min at -20° C. and then added in one portion to a solution of 32 mL of glacial acetic acid containing 690 mg of copper (I) chloride saturated with sulfur dioxide at 0° C. The resultant reaction mixture instantly changed in color from a dark green with nitrogen evolution to a lime green slurry as time progressed. The reaction mixture was allowed to warm from 0° C. to room temperature over 50 min. The mixture was then poured into ice-water and extracted with ethyl acetate. The combined organic extracts were washed once with cold water, dried over magnesium sulfate, filtered, and concentrated in vacuo to remove acetic acid. The crude sulfonyl chloride was purified by flash chromatography (silica gel, dichloromethane) to yield 3.4 g of the title compound as a white solid: 1H NMR (CDCl3) δ8.37 (d, 2H, J=9.1 Hz), 8.20 (d, 2H, J=8.6 Hz), 4.06 (t, 2H, J=7.1 Hz), 1.93 (m, 3H), 1.81 (m, 2H), 1.62 (m, 2H), 1.55 (m, 2H), 1.41 (m, 2H), 1.11 (m, 2H).

Provenance & Evidence