Preparation of N-(α,β-unsaturated acyl)-sulfonamides

Abstract

N-(α,β-Unsaturated acyl)sulfonamides are prepared (i) by the N-acylation of sulfonamides with N-(α,β-unsaturated acyl)benzotriazoles in the presence of potassium tert-butoxide or sodium hydride and (ii) by reactions of appropriate α,β-unsaturated carboxamides with sulfonylbenzotriazoles in the presence of sodium hydride. Published preparations of N-(α,β-unsaturated acyl)sulfonamides include (i) the acylation of sulfonamides (RSO2NH2) by (a) unsaturated acyl chlorides (R'CH=CHCOCl) in the presence of a base (such as triethylamine, 3,5a n-butyllithium, 4d or NaH 6,7 ) or a copper powder catalyst; 8 (b) unsaturated carboxylic acids via mixed anhydride in the presence of Lewis acid catalyst; 9 (ii) reactions of aryl isocyanates (RSO2NCO) with 1-alkenyltrialkylstannanes, di-1- alkenyldibutylstannanes in the presence of aluminium trichloride 10a or with substituted alkenes; 10b (iii) reactions of sulfonamide with the Wittig adduct obtained from (triphenylphosphoranylidene)ketene and an aldehyde; 11 (iv) coupling of unsaturated acids with sulfonamides in the presence of 1-ethyl-3-(3'-dimethylaminopropyl)carbodiimide (EDCI); 2,3,12 (v) dehydrogenation of the corresponding saturated analogs by using LDA followed by N-tert- butylbenzenesulfinimidoyl chloride. 5a,13 Herein, we report the acylation of sulfonamides with stable, crystalline N-(α,β-unsaturated acyl)benzotriazoles to give N-(α,β-unsaturated acyl)sulfonamides.