Given these results, we envisioned that the olefin transposition reactivity could be accessible by Mn-based systems. Herein we disclose that by masking the metal/NH cooperativity one can tune the reactivity of Mn hydrides from polar C=X (X = O, N) substrates to C=C bonds. With this strategy we develop the first highly selective olefin transposition reactions catalyzed by Mn(I), specifically an N-methylated Mn-CNP complex (Figure ). At the onset of investigation we screened the activity of several well-defined Mn(I) complexes reported by our group and others (Figure ) towards the transposition of 4allylanisole (1a) model substrate. The pre-catalysts Mn-3-5, 16j, 18 that were reported to be efficient for carbonyl hydro-genation, surprisingly displayed no reactivity in transposition with the exception of Mn-3 that gave 18% yield of isomerized product 2a (Table , entries 1-3).