Ammonium Chloride → N-(5-Chloro-1,3-thiazol-2-yl)-3-cyano-N-(2,4-dimethoxybenzyl)-4-fluorobenzenesulfonamide

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Under an atmosphere of nitrogen, 5-chloro-N-(2,4-dimethoxybenzyl)-1,3-thiazol-2-amine (Preparation 208, 3.0 g 10.5 mmol) was dissolved in tetrahydrofuran (20 ml) and cooled to −70° C. Lithium hexamethyldisilazane (1 M in tetrahydrofuran, 12.6 ml, 12.6 mmol) was added dropwise, keeping the temperature below −60° C. After 5 minutes, the cooling bath was removed and the reaction warmed to room temperature, stirred for a further 5 minutes then cooled back to −70° C. 3-Cyano-4-fluorobenzenesulfonyl chloride (2.54 g, 11.6 mmol) in tetrahydrofuran (10 ml) was added dropwise keeping the temperature below −60° C. and the reaction mixture was warmed to room temperature. Saturated aqueous ammonium chloride solution (50 ml) was added followed by water to dissolve the solid which had precipitated out. The aqueous layer was extracted with ethyl acetate (50 ml) and the organic extracts dried over magnesium sulphate and decolourising charcoal, filtered through Celite™ and the filtrate evaporated in vacuo. The resulting gum was purified using a short column (silica gel, 150 g) eluting with ethyl acetate:heptane (1:1, by volume) affording a gum which was triturated with tert-butyl ether, filtered, washed with heptane and dried in vacuo to give the title compound as a buff solid, 2.84 g, 57% yield.

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