Parallel synthesis of 1,2,4-oxadiazoles from carboxylic acids using an improved, uronium-based, activation

We describe the synthesis of 1,2,4-oxadiazoles from carboxylic acids and amidoximes using 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) as an activating agent of the carboxylic acid function for the O-acylation step. This method was used for the synthesis of a library of 24 1,2,4-oxadiazoles. (C) 2001 Elsevier Science Ltd. All rights reserved.