Synthesis and biological evaluation of 2,5-di(7-indolyl)-1,3, 4-oxadiazoles, and 2-and 7-indolyl 2-(1,3,4-thiadiazolyl)ketones as antimicrobials

A range of novel hydrazine bridged bis-indoles was prepared from readily available indole-7-glyoxyloylchlorides and 7-trichloroacetylindoles and underwent cyclodehydration to produce 2,5-di(7-indolyl)-1,3,4-oxadiazoles and a 2,2'-bi-1,3,4-oxadiazolyl with phosphoryl chloride in ethyl acetate. This efficient protocol was subsequently used for the synthesis of 2-and 7-indolyl 2-(1,3,4-thiadiazolyl) ketones from related indolyl-hydrazine carbothioamides. The synthesised bis-indoles were evaluated for their antimicrobial properties, particularly the inhibition of protein-protein complex formation between RNA polymerase andrfactor and their bactericidal effect on Gram positive Bacillus subtilis and Gram negative Escherichia coli. (C) 2014 Elsevier Ltd. All rights reserved.