Synthesis and Antimicrobial Activity of Salicylanilide Derivatives. II

Abstract

The condensation of 4-halo-o-toluidine with salicylic acid or 5-halosalicylic acid was carried out by the use of phosphorus trichloride in xylene to obtain the salicylanilides 1—13. 4-Halo (or nitro)-o-toluidine, 4-halo-o-nitroaniline or 2,4-dihaloaniline was condensed with 3,5-dihalosalicylic acid to provide the salicylanilides 14—30 by the same method. The salicylanilides 2-15, 26 and 27 gave the acetylated compounds 31—46 on treatment with acetic anhydride and pyridine. The salicylanilides 26 and 27 gave the methylated compounds 47 and 48 on treatment with dimethyl sulfate. In the antimicrobial activity tests of the synthesized compounds, 4'5-dihalo-2'-methylsalicylanilides 1—13 and the acetylated compounds 31—42 showed strong antimicrobial activity against some Eumycetes at the minimum inhibitory concentration (MIC) of 0.8μg/ml. Compound 3 was shown to have a strong preventive activity against downy mildew of cucumber. © 1984, The Pharmaceutical Society of Japan. All rights reserved.