Use of carborane carboxylic acids in the synthesis of boronated nitrogen heterocycles

A novel series of 5-substituted carborane tetrazoles was synthesized by acylation of 5-phenyl-1-H-tetrazole with the available o- and m-carborane carboxylic acid chlorides or o- and m-carborane acetic acid chlorides in the presence of pyridine. Successive thermolysis of the carborane tetrazoles in toluene followed by the extrusion of nitrogen resulted in a series of previously unknown carborane 1,3,4-oxadiazoles in good yield. Using 2,4-dichloroaniline as an example we showed that carborane-substituted 1,3,4-oxadiazoles can be converted into the corresponding 1,2,4-triazoles. (C) 2013 Elsevier Ltd. All rights reserved.