Unexpected Products of Benzylamine Oxidation Catalyzed by Manganese Porphyrins: Some Factors that Play a Critical Role for Imine Formation

• Published in: ChemistrySelect (Weinheim) 2019-03, Vol.4 (12), p.3275-3280
• Main Authors: Meireles, Alexandre Moreira, da Silva, Vinícius Santos, Rebouças, Júlio Santos, da Silva Martins, Dayse Carvalho
• Format: Article
• Language: English
• Subjects: Catalysis; Metalloporphyrins; Oxidative Coupling; PhIO; Schiff base
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201803128

This work describes the oxidation of benzylamine by PhIO, catalyzed by a series of first‐row metal salts and the respective first‐, second‐, and third‐generation metalloporphyrins. Five products were identified in reactions with [MnIIITPPCl]/PhIO. In this system, two products obtained (benzaldehyde oxime and N‐benzylbenzamide) were not previously described when [MnIIITPPCl] was used as catalyst. The change in the oxidant type (PhIO, PhI(OAc)2, H2O2 or m‐CPBA) modified the selectivity for the major product in the presence of [MnIIITPPCl]. For a second‐generation manganese porphyrin, the highest total yield was observed (99%), with 72% of imine product and only 1% of catalyst destruction, even in homogeneus system. Benzylamine was oxidized by metalloporphyrins in the presence of oxygen donors. Five products were observed in the [MnIIITPPCl]/PhIO system. Two unexpected products were observed for the first time. The selectivity for the major product could be modulated by the oxidant type and/or by the porphyrinic macrocycle.