Catalysed aerobic dehydrogenation of amines and an X-ray crystal structure of a bis(benzylamine) ruthenium(II) porphyrin species

Ruthenium‐Catalyzed Aerobic Oxidation of Amines

“…Aliphatic nitriles were found to be poorly compatible with this system and n ‐butylamine gave butyronitrile in only 25 % yield among other byproducts. This report laid the foundation for the development of numerous ruthenium‐based homogeneous catalytic systems for the aerobic oxidation of amines (Table ) . For example, James et al.…”

“…reported the synthesis of a ruthenium–porphyrin complex, trans ‐[Ru VI (tmp)(O) 2 ] (tmp=dianion of 5,10,15,20‐tetramesitylporphyrin), which was found to be effective towards the dehydrogenation of amines . This system exhibited 100 % selectivity under relatively mild reaction conditions ( T =50 °C), and both primary and secondary amines were converted to nitriles and imines, respectively, in the presence of air (Table ) . They proposed that there is an initial two‐electron oxidation of the primary amine substrate to imine and thereby [Ru VI (tmp)(O) 2 ] is reduced to the monooxo species [Ru IV (tmp)O].…”

Ruthenium Porphyrins with Axial π‐Conjugated Arylamide and Arylimide Ligands

“…Similarly, [Ru IV (por)(NH{Ar‐ p ‐Cl}) 2 ] (por=tmp, 4‐OMe‐tpp) were prepared in 78–88 % yields in this work (entries 14 and 15, Table 1). The reactions of [Ru VI (por)O 2 ] with alkylamines6d, 22, 23 and amino esters24 were reported to afford bis(amine)ruthenium(II) porphyrins. Other related reactivity of [Ru VI (por)O 2 ] include the reaction with benzophenone imine to give [Ru IV (por)(N=CPh 2 ) 2 ]22b or [Ru II (por)(NH=CPh 2 ) 2 ],25 and the reaction with 1,1‐diphenylhydrazine to give [Ru IV (por)(NHNPh 2 ) 2 ] 26…”

Interaction between Dioxoruthenium(VI) Porphyrins and Hydroxylamines: Coordination ofN-Substituted Hydroxylamine to Ruthenium and X-ray Crystal Structures of Ruthenium Complexes with a Unidentate Nitrosoarene Ligand

“…Mechanistic investigations reveal the formation of intermediates [Ru II (Por)(Ph-NO)(PhNHOH)] (5; Por porphyrin), a ruthenium complex with N-substituted hydroxylamine ligand, in the ª1 PhNHOHº system. The RuÀNH-(OH)Ph moiety in 5 undergoes no rapid exchange with free PhNHOH in solution at room temperature, as revealed by 1 Introduction Dioxoruthenium(vi) porphyrins, [Ru VI O 2 (Por)] (1; Por porphyrin), [1,2] exhibit a number of cytochrome P-450 type reactivities such as alkene epoxidation, [3±6] alkane hydroxylation, [7±9] and amine oxidation [10] (reactions (1) ± (3) in Scheme 1), and serve as unique precursors to bis-(amine)-, [11,12] bis(imine)-, [13] bis(amido)-, [12,14] bis(methyleneamido)-, [13] and bis(hydrazido)ruthenium porphyrins [15] (reactions (4) ± (8) in Scheme 1). Our interest in the interaction between complexes 1 and hydroxylamines stems from the discovery that oxidative degradation of N-alkylhydroxylamines in the presence of cytochrome P-450 leads to formation of stable nitrosoalkane complexes of the enzyme, [16,17] a reactivity well mimicked by the ª[Fe III (Por)Cl] RNHOH (R Me, iPr, PhCH 2 CH 2 )º model systems developed by Mansuy and co-workers.…”