Synthesis of new 1,2,4-oxadiazoles carrying (1'S,2'S)-t-butyloxycarbonyl-1-amino-2- methyl-1-butyl and (1'S)-t-butyloxycarbonyl-1'-amino-1'-ethyl groups at C-5

a facile and efficient synthesis of 3-aryl-5-[(1s)-t-butyloxycarbonyl-1-amino-(2 s)-methyl-1-butyl)]-1,2,4-oxadiazoles 4a-f and 3-phenyl-5-[(1s)-t-butyloxycarbonyl-1-amino-1-ethyl]-1,2,4 -oxadiazole 6 starting from arylamidoximes, n-t-boc-l-isoleucine and n-t- boc-l-alanine is decribed. the structures of the intermediates and final compounds have been deduced from spectroscopic data.