Three mononuclear nonheme iron and 2-oxoglutarate dependent enzymes, L-Ile 4-hydroxylase, L-Leu 5-hydroxylase and polyoxin dihydroxylase, are previously reported to catalyze the hydroxylation of L-isoleucine, L-leucine, and L-alpha-amino-delta-carbamoylhydroxyvaleric acid (ACV). In this study, we showed that these enzymes can accommodate leucine isomers and catalyze regiospecific hydroxylation. On the basis of these results, as a proof-of-concept, we demonstrated that the outcome of the reaction can be redirected by installation of an assisting group within the substrate. Specifically, instead of canonical hydroxylation, these enzymes can catalyze non-native nitrile group installation when an azido group is introduced. The reaction is likely to proceed through C-H bond activation by an Fe(IV)-oxo species, followed by azido-directed C N bond formation. These results offer a unique opportunity to investigate and expand the reaction repertoire of Fe/2OG enzymes.