One-Pot Synthesis of Sulfonamides from Amine-Sulfonate Salts
 Typical Procedure: To a solution of the amine (1 eq.) in a minimum amount of H2O-MeOH (60:40) is added the sulfonic acid (1 eq.). The reaction is stirred at room temperature for 15 min (the reaction is judged to be complete when pH paper indicates that the solution is neutral). The solution is evaporated under vacuum and the remaining solid is crystallized from hot MeOH. The crystals are dried in a vaccum oven for 24 h at 50℃. To a solution of the freshly prepared primary or secondary amine derived sulfonate salt (0.01 mol) in anhydrous MeCN (40 mL) is added cyanuric chloride (0.0033 mol) and the reaction mixture is stirred at room temperature for 30 min. Et3N (0.012 mol) is added and the solution is stirred for a further 30-90 min (until TLC indicates completion of the reaction). The reaction mixture is concentrated under vacuum and the residue is dissolved in CHCl3 (100 mL). The organic layer is washed with water (2 × 100 mL), dried over anhydrous Na2SO4 and evaporated in vacuo. The residue is purified by short column chromatography on silica gel eluting with a mixture of PE-EtOAc.
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