Biaryl sulfonamides from O‐acetyl amidoximes: 1,2,4‐Oxadiazole cyclization under acidic conditions

Abstract

AbstractA series of 4‐cyanobenzenesulfonamides (1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h) was converted to the corresponding O‐acetylated amidoximes (2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h). The reaction of 1a was exemplarily investigated with respect to the formation of a byproduct, which was identified as 1,2,4‐oxadiazole derivative 3a. This observation led to the development of an improved procedure for the preparation of 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h. Compounds 2 could be transformed to 1,2,4‐oxadiazoles 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h in high yields and purity upon heating in acetic acid. J. Heterocyclic Chem., (2011).