Re. Bolton et al., 3-SUBSTITUTED-1,2,4-OXADIAZOLIN-5-ONE - A USEFUL AMIDINE PRECURSOR AND PROTECTING GROUP, Tetrahedron letters, 36(25), 1995, pp. 4471-4474
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.