Porphycene-mediated photooxidation of benzylamines by visible light

Abstract

A variety of primary and secondary benzylic amines were oxidized efficiently to N-benzylidenebenzylamines and imines, respectively, using 2,7,12,17-tetrapropylporphycene (H(2)TPrPc) photocatalyst and blue light emitting diodes (LEDs). The photooxidation of 4-methoxybenzylamine in the presence of H(2)TPrPc and its tin(IV) complex Sn(TPrPc)Cl(2) was studied in detail in order to show that operating mechanisms can be different depending on the photosensitizer type. Two experiments involving solvent deuterium isotope effect and competitive quenching with DABCO provide evidence for the singlet oxygen mechanism as the major pathway in the H(2)TPrPc-catalyzed reaction and the predominance of the direct electron transfer from the photoexcited dye to the amine when the Sn(TPrPc)Cl(2) complex was used as a photocatalyst.

Recent Advances in Aerobic Oxidation of Alcohols and Amines to Imines

“…102 Up to 99% imines were obtained within 20 minutes, but prolonged reaction time or addition of water would result in dominating aldehyde byproducts. Control experiments revealed that the mechanism for 4-methoxybenzylamine oxidation was strongly dependent on the type of photosensitizer.…”

Organic Dye‐Photocatalyzed Acylnitroso Ene Reaction

“…To give evidence of the proposed pathway in which 1 a would be initially oxidized by RB*, we performed fluorescence quenching experiments (Stern–Volmer studies) of RB 20. Notably, the fluorescence intensity decreased in the presence of increasing concentration of 1 a (Figure 3).…”

Seaweed‐like 2D‐2D Architecture of MoS2/rGO Composites for Enhanced Selective Aerobic Oxidative Coupling of Amines

“…Then the final product of N ‐benzylidenebenzylamine could be obtained by reaction of the resulting benzaldehyde and benzylamine. Reaction following the pathway can be enhanced by addition of water and yield considerable amount of aldehyde byproducts . In pathway B, this NH‐imines intermediate can directly react with another molecular of benzylamine to yield aminal, which then releases ammonia to give the coupled N ‐benzylidenebenzylamine.…”

“…Reaction following the pathway can be enhanced by addition of water and yield considerable amount of aldehyde byproducts. [33][34][35] In pathway B, this NH-imines intermediate can directly react with another molecular of benzylamine to yield aminal, which then releases ammonia to give the coupled Nbenzylidenebenzylamine. In this catalytic system with MoS 2 /rGO catalysts, the direct bimolecular condensation (pathway B) may be favored as no benzaldehyde was observed during the reaction (see Figure S2 in SI).…”