3-SUBSTITUTED-1,2,4-OXADIAZOLIN-5-ONE - A USEFUL AMIDINE PRECURSOR AND PROTECTING GROUP

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 latte r compounds are readily prepared from amidoximes or alternatively via cycloaddition of nitrile oxides to trichloroacetonitrile and subsequen t hydrolysis. Both protecting groups may be readily removed upon hydro genation, liberating the parent amidine. In addition, 1,2,4-oxadiazoli n-5-ones may be utilised for the facile synthesis of N-alkyl amidines.