Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

Ligand properties of aromatic azines: C–H activation, metal induced disproportionation and catalytic C–C coupling reactions

“…Formally 7 is a Fe 2 (CO) 6 complex of a primary imine that also showed the reaction sequence of ortho-metallation and subsequent hydrogen transfer towards the imine carbon atom. The fact that in the related cleavage of an azine by a rhodium complex no imine and no complex of the imine was detectable [4] to our opinion is an additional hint that in the reaction described herein the cleavage of the N-N bond of the azine follows the reaction of the first imine moiety of the ligand. The hydrogen atom at the former imine nitrogen atom gives rise to characteristic signals in the IR-and NMR-spectra of 7 (cf.…”

“…To the best of our knowledge a reaction like this has not been reported from the treatment of azines with iron carbonyls. Very recently a closely related reaction was described starting from a rhodium pincer complex exhibiting the very labile dinitrogen ligand [4].…”

“…Most of the reactions lead to the symmetrical cleavage of the azine moiety producing two imide units which undergo subsequent reactions [3]. Very recently, the rhodium induced cleavage of an azine into a nitrile and a imine has been reported and the molecular structure of the corresponding nitrile complex was determined [4]. In context with our research on iron or ruthenium induced C-H activation reactions the reactivity of aromatic imines towards iron carbonyls was of considerable interest.…”

Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound

“…[16,17] Recently, Brown and co-workers reported the synthesis of stable adducts of these imines with boranes, as new intermediates for organic synthesis, [18] and Milstein and co-workers described the synthesis of a coordination compound of PhCH=NH by nonsymmetrical rhodium-mediated NÀN bond cleavage of aromatic azines. [19] With few exceptions, amino acid biodegradation involves the removal of the a-amino group to give the corresponding a-keto acid, and imines act as intermediates in this process. This reaction, catalyzed by aminotransferases, begins with the formation of a Schiff base between the pyridoxal 5'-phosphate and the corresponding amino acid, in tautomeric equilibrium between the aldimine and the ketimine forms.…”

The reaction of ortho-halogenated aromatic aldazine ligands with Fe2(CO)9: symmetrical cleavage of the azine and carbon–halogen activation

“…So we think that the formation of 2a is also due to a disproportionation of 1a into a primary imine and a nitrile and 2a being the product of the reaction of the nitrile with Fe 2 (CO) 9 . Recently, the rhodium induced cleavage of an azine into a nitrile and a imine has been reported and the molecular structure of the corresponding nitrile complex was determined [19].…”