Green Oxidation of Amines to Imines Based on the Development of Novel Catalytic Systems Using Molecular Oxygen or Hydrogen Peroxide

Abstract

Amines are transformed into the corresponding imines by environmentally benign catalytic oxidation reactions. Gaseous oxygen or hydrogen peroxide is used as the oxidant, and water is the only byproduct. When a vanadium complex is used as the catalyst in an ionic liquid, the amine oxidation successfully proceeds with recycling of the catalyst. Amine oxidation with hydrogen peroxide as an oxidant in water is also attained by using copper(II) sulfate as catalyst. In addition, photoinduced oxidation of amines to imines is conducted by using oxygen as the oxidant in the presence of a zinc-chlorin complex as catalyst.

Metal-Free Oxidative Coupling of Benzylamines to Imines under an Oxygen Atmosphere Promoted Using Salicylic Acid Derivatives as Organocatalysts

“…Recently, we have reported a series of eco-friendly oxidations of alcohols and amines using metal catalysts: for example, the vanadium complex-catalyzed oxidation of benzyl alcohols 25 or benzylamines with atmospheric O 2 in water or ionic liquid 26 and the copper sulfate-catalyzed oxidation of amines with H 2 O 2 in water 27 (Scheme 1, eqs 1 and 2, respectively). In the former catalytic oxidation, 3-hydroxypicolinic acid (H 2 hpic) or its analogues were used as ligands for oxovanadium complexes.…”

Chemoselective Catalytic Dehydrogenation of Benzylic Amines Driven by the TEtraQuinoline/FeCl2 Complex

“…[3][4][5][6][7][8][9][10] In this context, various types of transition metal complexes were identified to render this specific transformation using peroxides as oxidants. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] Iron catalysis has attracted sustained attention due to the abundance of iron in nature, and aerobic oxidative conditions promoted by iron complexes were disclosed. [25][26][27] Recently, we unveiled TEtraQuinoline (TEQ) as a novel nonflat porphyrinoid tetradentate nitrogen ligand whose iron complex promotes dehydrogenation of tetrahydroquinolines and benzylic oxidation of dihydroanthracene.…”

“…Hence, the conversion of amines to imines allows for both fragmentation and diversification of molecular complexity, and a reliable catalytic protocol has thus been sought for decades [3–10] . In this context, various types of transition metal complexes were identified to render this specific transformation using peroxides as oxidants [11–24] . Iron catalysis has attracted sustained attention due to the abundance of iron in nature, and aerobic oxidative conditions promoted by iron complexes were disclosed [25–27] .…”

MOF-Based Materials with Sensing Potential: Pyrrolidine-Fused Chlorin at UiO-66(Hf) for Enhanced NO2 Detection

“…The incorporation of chlorins into MOF materials has been predominantly studied in the area of photodynamic therapy (PDT) of cancer, where chlorin e6 (Figure 1a) stands out as the photosensitizer of choice [49][50][51][52]. On the other hand, N-methylpyrrolidine-fused chlorins are more stable than the hydrogenated chlorins and have been studied mostly as photosensitizers in the photodynamic inactivation of bacteria [53][54][55] and PDT of cancer [56][57][58][59], as well as reaction [60], biomimetic [61], and oxidation [62] catalysts.…”