Journal
ACS CATALYSIS
Volume 9, Issue 2, Pages 1066-1080Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.8b03993
Keywords
copper; ketone; C-C activation; oxygen; aldehyde; acid
Categories
Funding
- National Natural Science Foundation of China [21702119, 21473100, 21873055]
- Natural Science Foundation of Shandong Province, China [ZR2017QB001, ZR2016JL012]
Ask authors/readers for more resources
Cu-catalyzed aerobic C(CO)-CH3 activation of (hetero)aryl methyl ketones provides a rare tool for aldehyde formation from ketones through oxidative processes. To elucidate the detailed reaction mechanism, a combined computational and experimental study was performed. Computational study indicates a dinuclear Cu-catalyzed spin-crossover-involved mechanism explains the aldehyde formation. Meanwhile, alpha-mono(hydroxy)-acetophenone int1 was found to be the real active intermediate for the formation of benzaldehyde pro1 from acetophenone sub1. sub1 transforms into int1 via oxygen activation and rate determining C-alpha-H activation. The resulting dinuclear Cu complex regenerates the active Cu(I) complex through spin-crossover involved disproportionation and retro oxygen activation. int1 further generates pro1 via oxygen activation, O-H activation, iodide atom transfer, 1,2-H shift, ligand rotation, spin crossover, and nucleophilic substitution. By comparison, the previously proposed reaction route involving alpha,alpha-bis(hydroxy)acetophenone int3 is less kinetically favorable overall, but int3 can generate pro1 faster than int1 does via a dehydrogenation mechanism. These mechanistic discoveries are consistent with the previously reported KIE effect, deuterium-labeling experiment, different reactivity of sub1, int1 and int3, and detection of H-2 and CO2. Furthermore, computational study unexpectedly revealed the competitive generation of aromatic acids in the C(CO)-CH3 activation process for especially electron-rich substrates. This reaction route is supported by the experimental study, which confirmed the aromatic acid formation in Cu-catalyzed aerobic C(CO)-CH3 cleavage of ketones and excluded the in situ oxidation of aldehyde products to aromatic acid products.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available