Abstract: A novel anti-oncogenic azatyrosine analogues of formula (I) ##STR1## wherein R.sub.1 is C.sub.1-6 alkyl, C.sub.1-6 haloalkyl, benzyl, or (C.sub.1-6 alkyl)carbonyl; R.sub.2 is C.sub.1-6 alkyl, C.sub.1-6 haloalkyl, or C.sub.1-6 alkoxyl; and R.sub.3 is CONR.sub.4 R.sub.5, CONHNR.sub.4 R.sub.5, or COOR.sub.6, wherein each R.sub.4 and R.sub.5 independently is a hydrogen, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, or C.sub.3-6 cycloalkyl, or R.sub.4 and R.sub.5 taken together with the nitrogen attached thereto form a C.sub.3-8 heterocyclic group; R.sub.6 is C.sub.1-6 alkyl, C.sub.1-6 haloalkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, C.sub.3-6 cycloalkyl, or benzyl. Also disclosed is a method of preparing such a novel anti-oncogenic azatyrosine analogues, as well as a pharmaceutical composition containing a compound of formula (I).