MnO₂@Fe₃O₄ Magnetic Nanoparticles as Efficient and Recyclable Heterogeneous Catalyst for Benzylic sp³ C−H Oxidation

Abstract

Herein, we report a highly chemoselective and efficient heterogeneous MnO2@Fe3O4 MNP catalyst for the oxidation of benzylic sp3 C−H group of ethers using TBHP as a green oxidant to afford ester derivatives in high yield under batch/continuous flow module. This catalyst was also effective for the benzylic sp3 C−H group of methylene derivatives to furnish the ketone in high yield which can be easily integrated into continuous flow condition for scale up. The catalyst is fully characterized by spectroscopic techniques and it was found that 0.424 % MnO2@Fe3O4 catalyzes the reaction; the magnetic nanoparticles of this catalyst could be easily recovered from the reaction mixture. The recovered catalyst was recycled for twelve cycles without any loss of the catalytic activity. The advantages of MnO2@Fe3O4 MNP are its catalytic activity, easy preparation, recovery, and recyclability, gram scale synthesis with a TOF of up to 14.93 h−1 and low metal leaching during the reaction.

Boosting Solvent-Free Aerobic Oxidation of Benzylic Compounds into Ketones over Au-Pd Nanoparticles Supported by Porous Carbon

“…Yet, these methods suffer from serious drawbacks, such as excessive use, difficult separation, and recovery, as well as a lack of reuse of these reagents or catalysts [6][7][8]. To overcome the above problems, substantial endeavors have been devoted to developing more environmentally heterogeneous catalytic systems for the selective oxidation of benzyl compounds [9][10][11][12][13]. Various catalysts, including MnO 2 @Fe 3 O 4 nanoparticles [10], Cu 3 (PO 4 ) 2 [11], LaMO 3 (M = Cr, Co, Fe, Mn, Ni) perovskites [12], and Cr/MCM-41 [13], have been explored for the oxidation of the C-H bonds of benzyl compounds by combining with oxidants.…”

Continuous-flow Fe-zeolite-catalyzed temperature-directed synthesis of bioactive tetraketones and xanthenes using epoxides and cyclic-1,3-diketones via a Meinwald rearrangement

“…31 We also reported the magnetic iron oxide nanoparticles-catalyzed C–H peroxidation 32 and MnO 2 @Fe 3 O 4 magnetic nanoparticles-catalyzed oxidation of benzylic sp 3 C–H groups under a continuous flow process. 33…”

“…31 We also reported the magnetic iron oxide nanoparticles-catalyzed C-H peroxidation 32 and MnO 2 @Fe 3 -O 4 magnetic nanoparticles-catalyzed oxidation of benzylic sp 3 C-H groups under a continuous flow process. 33 Herein, we report the direct synthesis of tetraketone from epoxide and cyclic-1,3-diketone using an environmentally benign Fe-zeolite catalyst for the first time. In addition, the same Fe-zeolite catalyst facilitated the cyclization reaction of tetraketone under high heating to form bioactive xanthene derivatives in a high yield.…”

Cu2O−CD nanosuperstructures as a Biomimetic Catalyst for Oxidation of Benzylic sp3 C−H bonds and Secondary Amines using Molecular Oxygen: First Total Synthesis of proposed Swerilactone O

“…Many such strategies integrating transition-metal catalysts along with oxygen or peroxides as the terminal oxidants have seen limelight. [4,5] A plethora of metal catalysts are showcased for the benzylic sp 3 CÀ H bond oxidation reactions, such as those involving chromium, [6][7][8][9][10][11][12][13] manganese, [14][15][16][17] iron, [18][19][20][21][22][23][24] cobalt, [25][26][27][28][29] bismuth, [30,31] ruthenium, [32][33][34] and rhodium. [35,36] Yet, many of these metal catalysts are toxic, expensive, functional only in organic solvents, involve the use of peroxides, and are also nonrecoverable which are the limitations of these protocols.…”