Ene Reactivity of an Fe═NR Bond Enables the Catalytic α-Deuteration of Nitriles and Alkynes.

Herein, we report the reactions of an Fe(II) imido complex [Ph 2 B( t BuIm) 2 Fe═NDipp] - ( 1 ) with internal alkynes and isobutyronitrile, affording the Fe amido allenyl complexes [Ph 2 B( t BuIm) 2 Fe(NHDipp)((R 1 )C═C═C(R 2 )(H))] - (R 1 = Et or n Pr; R 2 = Me or Et, 2-5 ) and the Fe amido keteniminate complex [Ph 2 B( t BuIm) 2 Fe(NHDipp)(N═C═CMe 2 )K(THF)] n ( 8-K ), respectively. These transformations represent the previously unknown ene-like reactivity of a metal-ligand multiple bond. Stoichiometric reactions of 2 and 8-K with DippNH 2 lead to the regeneration of 3-hexyne and isobutyronitrile, respectively, with concomitant formation of the bis(anilido) complex [Ph 2 B( t BuIm) 2 Fe(NHDipp) 2 ] - ( 9 ). These results provide the platform for 1 as an efficient catalyst for the selective α-deuteration of nitriles and alkynes by RND 2 . These results demonstrate a new reaction mode for metal imido complexes and suggest new avenues for using the imido ligand in catalysis.