3-substituted-1,2,4-oxadiazolin-5-one; A useful amidine precursor and protecting group

Abstract

5-Benzyloxy-1,2,4-oxadiazoles and 1,2,4-oxadiazolin-5-ones are useful precursors to, and protecting groups for the amidine moiety. The latter compounds are readily prepared from amidoximes or alternatively via cycloaddition of nitrile oxides to trichloroacetonitrile and subsequent hydrolysis. Both protecting groups may be readily removed upon hydrogenation, liberating the parent amidine. In addition, 1,2,4-oxadiazolin-5-ones may be utilised for the facile synthesis of N-alkyl amidines.