A Visible-Light Promoted Amine Oxidation Catalyzed by a Cp*Ir Complex

Article abstract of DOI:10.1002/cctc.202000488

Through a rapid screening of Cp*Ir complexes based on a turn-on type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2’,3’-c]phenazine)Cl]⁺ complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H₂O₂ generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.

Full text of DOI:10.1002/cctc.202000488

The European Society Journal for Catalysis
Supported by
Accepted Article
Title: A visible-light promoted amine oxidation catalyzed by a Cp*Ir
complex
Authors: Holly Jane Davis, Daniel Häussinger, Thomas R. Ward, and
Yasunori Okamoto
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To be cited as: ChemCatChem 10.1002/cctc.202000488
Link to VoR: https://doi.org/10.1002/cctc.202000488
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1/2020

ChemCatChem
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COMMUNICATION
A visible-light promoted amine oxidation catalyzed by a Cp*Ir
complex
[a]
[b]
[a]
[a, c]
Holly Jane Davis, Daniel Häussinger, Thomas R. Ward* and Yasunori Okamoto,*
[a]
Dr. H. J. Davis, Prof. Dr. T. R. Ward, Prof. Dr. Y. Okamoto
Department of Chemistry
University of Basel
Mattenstrasse 24a, BRP 1096 Rosental CH-4058 Basel, Switzerland
E-mail: thomas.ward@unibas.ch, yasunori.okamoto@tokohu.ac.jp
PD. Dr. D. Häussinger
[
b]
c]
Department of Chemistry
University of Basel
St. Johanns-Ring 19 CH-4056 Basel, Switzerland
Prof. Dr. Y. Okamoto
[
Frontier Research Institute for Interdisciplinary Science
Tohoku University
2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 Japan
Supporting information for this article is given via a link at the end of the document.
Abstract: Through a rapid screening of Cp*Ir complexes based on a
displaying different pharmacological properties.23 MAO
selectively catalyzes only the first oxidation step, whereas CAD
generally results in the fully perdehydrogenated product.5-22
turn-on type fluorescence readout,
a [Cp*Ir(dipyrido[3,2-a:2’,3’-
+
c]phenazine)Cl] complex was found to catalyze the blue-light
promoted dehydrogenation of N-heterocycles under physiological
conditions. In the dehydrogenation of tetrahydroisoquinolines, the
catalyst preferentially yielded the monodehydrogenated product,
2 2
accompanying H O generation. We surmise that this mechanism
may be reminiscent of flavin-dependent oxidases.
Monoamine oxidase (MAO) is a flavin-dependent enzyme
that catalyzes the oxidation of a wide range of amines,
including N-heterocycles, using molecular oxygen as a
terminal oxidant (Scheme 1a). N-heterocycles are ubiquitous
compounds widely represented in active pharmaceutical
ingredients (APIs). Hence, MAOs have been engineered to
improve their substrate scope, selectivity, and stability for
industrial purposes.1
Scheme 1. Dehydrogenations of N-heterocycles catalyzed by (a) monoamine
oxidase (MAO) and (b) metal complexes.
To complement enzymes, organometallic catalysts have
been developed for the dehydrogenation of N-heterocycles.2,3 To
drive the oxidation of amines to completion, most organometallic
catalysts require a sacrificial hydrogen acceptor, an undesirable
From the viewpoint of sustainable chemistry, a synthetic
catalyst working in water under mild conditions is in high demand
to reduce its environmental impact.24 Moreover, such a synthetic
catalyst is also applicable to chemoenzymatic multistep
transformation enabled by concurrent use of synthetic catalysts
and enzymes.25 Here, we report on our efforts to develop an
organometallic catalyst for the selective monodehydrogenation of
N-heterocycles under mild conditions, comparable to those of
typical enzymatic transformations.
4
feature from an atom-economical perspective. Pioneering efforts
in catalytic acceptorless dehydrogenation (CAD) have been
reported by Yamaguchi and Fujita,5-7 Xiao,8,9 and Crabtree10 using
Cp*Ir(III) pianostool- and cationic iridium complexes (Scheme 1b).
CAD requires no external sacrificial oxidant and releases
dihydrogen as sole by-product. Although great progress has been
achieved,11-18 most of the CADs are carried out in organic solvent
or under strongly alkaline conditions at high temperature.
Noteworthy exceptions include work by Li19 and Kanai’s20,21
tandem catalysis as well as Crabtree’s22 electrocatalysis. In the
As MAO plays an important role in maintaining homeostasis
of neurotransmitters, the pro-fluorescent substrate 1 has been
widely used to monitor its activity (Scheme 2a).26 We were
pleased to find that the caged umbelliferone substrate 1 can be
also used as a turn-on probe to the catalyst’s dehydrogenation
activity. Upon dehydrogenation of the N-heterocycle, the
fluorescent coumarin moiety 2 is uncaged, allowing the evaluation
of catalytic activity. This strategy enabled us to conveniently
screen Cp*Ir-based catalysts for the dehydrogenation of substrate
1. Commercially-available bidentate ligands L^L 4-21 (5.5 mol%)
were screened in the presence of [Cp*IrCl2]2 3 (2.5 mol%) in
phosphate-buffered saline (PBS, pH 7.4) containing 5% DMSO at
context of
2
H -storage, it may be advantageous to fully
dehydrogenate the N-heterocycles, thus maximizing the
hydrogen-gravimetric capacity. For API synthesis however, the
perdehydrogenation may be a drawback (Scheme 1b). For
example, tetrahydroharmine, harmaline, and harmine, are all
naturally occurring N-heterocyclic alkaloids sharing the β-
carboline structure, differing only in their degree of saturation but
1
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Scheme 2. (a) A turn-on type fluorescent probe 1 to detect MAO activity. Screening of catalytic activities of in situ formed complexes comprised of (b) [Cp*IrCl
and (c) bidentate ligands 4-21 (d) relying on the uncaging of the probe 1 upon amine oxidation. Reaction conditions: 50 μM [Cp*IrCl 3, 110 μM Ligand 4 - 21 and
mM fluorescent probe 1 in PBS at 37 °C for 24 h. a An isolated [Cp*Ir(L^L 17)Cl](CF
SO ) (100 μM) was used. Fluorescence intensities (excitation at 320 nm and
2 2
] 3
2 2
]
2
3
3
emission at 450 nm) of reaction mixtures in a 96-well plate are measured by a plate reader. Each value and average values of duplicate (entries 1–15, 19–22) and
triplicate (entries 16-18) are displayed dots and bars respectively.
3
7 °C (Scheme 2b, c). After 24 h, an aliquot (2 μl) was diluted with
abstraction from the amine can occur from either of the 1 or 3-
position of amine 22. Abstraction at the N-α benzylic site, 1-
position, will generate a significantly more stable radical than that
at the competing 3-position, leading to the observed major
product 23. The generation of 24, on the other hand, can proceed
via two pathways: either via the less favourable abstraction at the
PBS (198 μl) in a 96-well plate, and the corresponding catalytic
activity was determined by fluorescence (excitation at 320 nm and
emission at 450 nm). Unexpectedly, none of the ligands displayed
a significant increase in fluorescence compared to the negative
control (Scheme 2d, grey bars). Inspired by Miller’s work on the
photo-acceleration of CAD catalyzed by [Cp*Ir(L^L 8)Cl]+ and
alternative site, tautomerisation and
a
second, favored,
[
Cp*Ir(L^L 10)Cl]+,27 we repeated the screening in a photoreactor
dehydrogenation event, or from direct tautomerisation from 23
before the second dehydrogenation. Potential interconversion of
imine 23 and its isomer 1,4-dihydroisoquinolines is proposed to
equipped with ca. 0.25 W blue LEDs (Scheme 2d, blue bars).
Gratifyingly, the dipyrido[3,2-a:2’,3’-c]phenazine 17 (Scheme 2d,
entry 16) yielded the highest activity under photo-irradiation.
Increased fluorescence was also observed for ligands L^L 10, 11,
8
be mediated by a transient Cp*Ir–H species (Fig S3). As the ratio
23:24 does not vary over the course of the reaction, this suggests
that [Cp*Ir(L^L 17)Cl]+ cannot reversibly convert 23 and 1,4-
dihydroisoquinoline. We thus hypothesize that the commonly
observed Cp*Ir–H species is not formed during this catalytic
cycle.6,8,30,31 The limited formation of the perdehydrogenated
product 24 may arise from the disfavored H-abstraction at the N-
adjacent 3-position or benzylic 4-position of amine 22. This is
supported by the fact that the dehydrogenation of imine 23 gave
24 with 12% yield, comparable to the yield of perdehydrogenated
product 24 obtained upon dehydrogenation of amine 22 (8%,
1
4, and 18 (Scheme 2d, entries 9, 10, 13, and 19). Almost no
enhancement was observed for either [Cp*IrCl 3 or L^L 17
2 2
]
+
alone, suggesting that the [Cp*Ir(L^L 17)Cl] complex, formed in
situ, is the active catalyst (Scheme 2d, entries 2, 17, and 16). To
determine its catalytic performance, complex [Cp*Ir(L^L 17)Cl]+
was synthesized (Fig. S1).28,29 Compared to the in situ-formed
complex, the isolated complex displayed slightly improved activity
(
Scheme 2d, entries 16 and 18), which suggests that the in situ
complexation is nearly quantitative.
1
As a benchmark reaction, we selected the dehydrogenation
of salsolidine 22 (1-methyl-6,7-dimethoxy-1,2,3,4-tetrahydro-
isoquinoline, Scheme 3a), a natural alkaloid. While no conversion
was observed under dark conditions, photo-irradiation promoted
the reaction, leading to nearly quantitative consumption of the
starting material 22 after 48 h, (Scheme 3b and Fig. S2). The
dehydrogenated product 23 and the perdehydrogenated product
Scheme 3b). Indeed, scrutiny of the H-NMR spectrum (Fig. S4),
revealed no hydride signal (typically found around – 11 to – 15
ppm). This is consistent with the preferential formation of the
mono-dehydrogenated product 23. We thus hypothesize that the
reaction proceeds instead via a radical-based mechanism.
To probe whether atmospheric oxygen may be the terminal
hydrogen acceptor, the presence of hydrogen peroxide was
2
4 were formed in 87% and 8% yield respectively. It was again
investigated. For this purpose, H
2
O
2
was quantified using
and 2,2’-azino-bis(3-
confirmed that L^L 17 alone does not catalyze this reaction. As H-
horseradish peroxidase (HRP)
2
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COMMUNICATION
ethylbenzothiazoline-6-sulfonic acid) (ABTS) to afford
a
Table 1. Photocatalytic dehydrogenation of salsolidine 22a
characteristic increase in absorbance at 405 nm.32 As highlighted
Entry
TEMPO
Under Air/N
2
23
%
24 %
2 2
in Scheme 3b, the generation of H O neatly reflects the oxidation
1
2
3
–
40 mM
–
Air
Air
78
8
of salsolidine 22 when the reaction is performed under air.
25
30
15
3
N
2
a
Experimental details as listed in Scheme 3, with a reaction time = 45 h.
Under anaerobic conditions, no resonance in the iridium
1
hydride region was observed by H-NMR spectrum, despite
repeated efforts (Fig. S4). While this does not preclude the
possibility of a transient Ir–H species, the marked preference
of mono- vs. perdehydrogenation suggests an alternative
pathway. During these investigations, an air-sensitive blue
complex was observed, which was scrutinized by UV-vis and
NMR spectroscopy (Scheme 4a and see discussion in the
page S23 for the emission studies).
Scheme 3 Time-course evolution of (a, b) the dehydrogenation of salsolidine
+
2
2 and (c) H
2
O
2
catalyzed by [Cp*Ir(L^L 17)Cl] . Experimental conditions: 100
+
μM [Cp*Ir(L^L 17)Cl] , 20 mM salsolidine 22 in 100 mM NaPi (pH 7.0) at 37 °C
under single blue LED irradiation. Concentrations of 22–24 were determined by
1H-NMR spectroscopy by using 1,3,5-trimethoxybenzene as an internal
2 2
standard. H O was quantitated by HRP colorimetric assay. Average values and
standard deviation for triplicate reactions are displayed.
To gain further mechanistic insight, we carried out the
dehydrogenation of substrate 22 in the presence of TEMPO
(
Table 1). Addition of excess TEMPO decreased the conversion
by factor of three. Taken together with the fact that
substoichiometric amounts of TEMPO shut down the reactivity of
Ir-H species,33 it is suggested that catalytically-generated 1
a
O
2
and/or radical species may be involved. This conclusion is
reached because TEMPO is known to mediate the conversion of
–
34
the O
with 1
2
radical to H
2
O
2
but also to trap radical species and react
O
2
which would unproductively deplete the finite oxygen
supply. Accordingly, experiments carried out in the presence of
9
,10-dimethylanthracene, as a 1O
2
trap, suggest that [Cp*Ir(L^L
+
1
7)X] may sensitize O
2
likely due to the extended aromatic nature
may play a role as an active
of L^L 17 and the generated 1
O
2
oxidizing species (Table S5 and path1 in Scheme 4b).
Scheme 4. (a) UV-vis spectra and their differential spectra of [Cp*Ir(L^L 17)Cl]+
under different conditions (b) Proposed mechanism
To confirm the involvement of oxygen in the mechanism, an
anaerobic reaction was performed. Unexpectedly, conversion
was observed under these conditions, albeit to a lesser extent:
~
38% conversion under aerobic conditions (Table 1). We
Upon photoirradiation under anaerobic conditions,
1
hypothesized that the cosolvent, DMSO present in 5% v/v may
act as the oxidizing agent in the absence of dioxygen as observed
by Das and coworkers.35 Substituting DMSO with DMF however,
led to conversion both with and without dioxygen (Table S7). We
assume that, in the absence of oxygen, the reaction proceeds via
an alternative mechanism. One of the possible explanations is
absorption from 435 to 700 nm increased and the H-NMR
resonances for L^L 17 were shifted upfield, leading us to
+
suggest that this species is [Cp*Ir(L^L 17
H
2
)X] , whereby the
ligand 17 has been reduced across the heteroaromatic ring
Scheme 4b, Fig. S5 and S7 – S10).35-37 The blue complex
remains moderately stable under nitrogen for > 1 week
(
2 2 2
generation of H instead of H O , like a typical CAD-type pathway.
without an increase in consumption of amine 22. This leads
+
However, the unambiguous detection of
experimental set-up proved challenging.
H
2
under our
us to suggest that intermediate [Cp*Ir(L^L 17
photoexcitation to be turned over (Fig. S6).
H
2
)X] requires
3
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COMMUNICATION
When exposed to air, [Cp*Ir(L^L 17
single species. Based on 1H NMR spectra, we conclude it
22 +
most resembles the [Cp*Ir(L^L 17) ] (Fig. S5). This
H
2
)X]+ produced a
Science Foundation (grant 200020_182046), the NCCR
Molecular Systems Engineering. HJD thanks the Marie
Skłodowska-Curie H2020-MSCA-IF-2018 for a postdoctoral
fellowship. YO thanks JST ACT-X (JPMJAX1913) and support
from FRIS, Tohoku University.
suggests that the catalyst reduction is caused by an unbound
equivalent of the amine substrate (Table S9). The differential
spectrum (E–C, in Scheme 4a) reveals the production of
imine 23 without affecting any other components during
photoreduction and oxidation of the catalyst. Upon
Keywords: Photocatalysis • Selective-dehydrogenation •
regeneration of the reduced catalyst by O
2
, [Cp*Ir(L^L
)X] may act as a 2e /2H donor in the reduction of O
(path 2 in Scheme 4b).35 This mechanism is
to produce H
Biomimetic • Reaction-in-water • Organometallic complex
+
–
+
1
7
H
2
2
[1]
V. F. Batista, J. L. Galman, D. C. G. A. Pinto, A. M. S. Silva and N. J.
Turner, ACS Catal. 2018, 8, 11889-11907.
2
O
2
reminiscent of flavin-dependent oxidases. We thus
tentatively propose an aerobic mechanism mediated by
singlet oxygen, or a mechanism involving L^L 17 reduction.
[
[3]
2]
G. E. Dobereiner and R. H. Crabtree, Chem. Rev. 2010, 110, 681-703.
J. Choi, A. H. R. MacArthur, M. Brookhart and A. S. Goldman, Chem.
Rev. 2011, 111, 1761-1779.
R. A. Sheldon, J. R. Soc. Interface 2016, 13, 1-7
R. Yamaguchi, C. Ikeda, Y. Takahashi and K.-I. Fujita, J. Am. Chem.
Soc. 2009, 131, 8410-8412.
K.-I. Fujita, Y. Tanaka, M. Kobayashi and R. Yamaguchi, J. Am. Chem.
Soc. 2014, 136, 4829-4832.
K.-I. Fujita, T. Wada and T. Shiraishi, Angew. Chem. Int. Ed. 2017, 56,
[4]
+
Next, [Cp*Ir(L^L 17)Cl] was tested for the reduction of N-
[5]
heterocycles, derived either from tetrahydroisoquinoline or
[
6]
7]
indoline 26
–
32 (Fig. 1).37 Higher TON and selectivity
[
correlate well with the stability of the C-centered radical with
a modest contribution from steric hindrance, rendering the H
atom less accessible for abstraction. The acyclic substrate
10886-10889.
[8]
J. Wu, D. Talwar, S. Johnston, M. Yan and J. Xiao, Angew. Chem. Int.
Ed. 2013, 52, 6983-6987.
D. Talwar, A. G. de Castro, H. Y. Li and J. Xiao, Angew. Chem. Int. Ed.
2015, 54, 5223-5227.
[9]
3
3 was also oxidized and subsequently hydrolyzed. In
[
10]
M. G. Manas, L. S. Sharninghausen, E. Lin and R. H. Crabtree, J.
Organomet. Chem. 2015, 792, 184-189.
C. Gunanathan and D. Milstein, Science 2013, 341, 1229712.
S. Chakraborty, W. W. Brennessel and W. D. Jones, J. Am. Chem. Soc.
analogy to substrates 26 and 28, the amine oxidation seems
to proceed at the less hindered N-α position. In all cases,
however, the dehydrogenation product was formed
preferentially over the perdehydrogenation product.
[11]
12]
[
2
014, 136, 8564-8567.
R. Xu, S. Chakraborty, H. Yuan and W. D. Jones, ACS Catal. 2015, 5,
350-6354.
[13]
6
[14]
[15]
[16]
[17]
[18]
M. Kojima and M. Kanai, Angew. Chem. Int. Ed. 2016, 55, 12224-12227.
Q. Yin and M. Oestreich, Angew. Chem. Int. Ed. 2017, 56, 7716-7718.
Á. Vivancos, M. Beller and M. Albrecht, ACS Catal. 2017, 8, 17-21.
R. Wang, H. Fan, W. Zhao and F. Li, Org. Lett. 2016, 18, 3558-3561.
H. Fan, W. Zhang, W. Zhao and F. Li, ChemistrySelect 2017, 2, 5735-
5739.
[
19]
20]
K. H. He, F. F. Tan, C. Z. Zhou, G. J. Zhou, X. L. Yang and Y. Li, Angew.
Chem. Int. Ed. 2017, 56, 3080-3084.
S. Kato, Y. Saga, M. Kojima, H. Fuse, S. Matsunaga, A. Fukatsu, M.
Kondo, S. Masaoka and M. Kanai, J. Am. Chem. Soc. 2017, 139, 2204-
[
2
207.
H. Fuse, M. Kojima, H. Mitsunuma and M. Kanai, Org. Lett. 2018, 20,
042-2045.
O. R. Luca, D. L. Huang, M. K. Takase and R. H. Crabtree, New J. Chem.
013, 37, 3402-3405.
H. Song, Y. Liu, Y. Liu, L. Wang and Q. Wang, J. Agric. Food Chem.
014, 62, 1010-1018.
T. Kitanosono, K. Masuda, P. Xu and S. Kobayashi, Chem. Rev. 2018,
18, 679-746.
N. J. Turner, Nature 2018, 560, 310-311.
S. Long, L. Chen, Y. Xiang, M. Song, Y. Zheng and Q. Zhu, Chem.
Commun. 2012, 48, 7164-7166.
S. M. Barrett, S. A. Slattery and A. J. M. Miller, ACS Catal. 2015, 5,
6320-6327.
[
[
[
[
21]
22]
23]
24]
2
2
2
Figure 1. Photocatalytic dehydrogenation of N-heterocycles 22, 26 – 32 and
1
+
acyclic substrate 33 catalyzed by [Cp*Ir(L^L 17)Cl] . Experimental conditions:
[
[
25]
26]
+
1
00 μM [Cp*Ir(L^L 17)Cl] , 20 mM 22, 26 - 33 in 100 mM NaPi (pH 7.0) at 37 °C
under blue LED irradiation for 48 h in the presence of air. TONs are determined
1
by H-NMR by using an internal standard. Average values for triplicate reactions
[27]
are displayed and mono vs. perdehydrogenation ratio shown in brackets.
[28]
D. Herebian and W. S. Sheldrick, J. Chem. Soc., Dalton Trans. 2002,
966-974.
[
29]
X. Duan, D. Liu, C. Chan and W. Lin, Small 2015, 11, 3962-3972.
Z. Liu, R. J. Deeth, J. S. Butler, A. Habtemariam, M. E. Newton and P.
J. Sadler, Angew. Chem. Int. Ed. 2013, 52, 4194-4197.
S. Ogo, R. Kabe, H. Hayashi, R. Harada and S. Fukuzumi, Dalton Trans
2006, 305, 4657-4663.
R. L. Peterson, J. W. Ginsbach, R. E. Cowley, M. F. Qayyum, R. A.
Himes, M. A. Siegler, C. D. Moore, B. Hedman, K. O. Hodgson, S.
Fukuzumi, E. I. Solomon and K. D. Karlin, J. Am. Chem. Soc. 2013, 135,
1645416467.
In summary, we have identified a visible light-promoted
+
[30]
dehydrogenation catalyst, [Cp*Ir(L^L 17)Cl] , which is active
under physiological conditions. Depending on the presence
[
31]
32]
[
2
or absence of O , we surmize that the reaction proceeds via
two competing reaction pathways. Detailed mechanistic
studies are underway alongside the introduction of the
reaction into a chemoenzymatic cascade.25
[33]
A. C. Albéniz, P. Espinet, R. López-Fernández and A. Sen, J. Am. Chem.
Soc. 2002, 124, 11278-1279
[34]
[33]
[34]
N. A. Romero, K. A. Margrey, N. E. Tay and D. A. Nicewicz Science
2015, 349, 1326-1330
D. Riemer, W. Schilling, A. Goetz, Y. Zhang, S. Gehrke, I. Tkach, O.
Hollóczki and S. Das, ACS Catal. 2018, 8, 11679-11687
K. Kobayashi, H. Ohtsu, K. Nozaki, S. Kitagawa and K. Tanaka, Inorg.
Chem. 2016, 55, 2076-2084
Acknowledgements
The authors acknowledge Dr. Alessandro Prescimone, Mr.
Adriano d’Addio and Mr. Daniel Joss for their help with the X-
ray crystal structure analysis and NMR measurements. TRW
acknowledges continued support from the Swiss National
[35]
D. A. McGovern, A. Selmi, J. E. O’Brien, J. M. Kelly and C. Long, Chem.
Commun. 2005, 1402-1404.
B. König and R. Lechner, Synthesis 2010, 10, 1712-1718.
Under optimized conditions, it is suggested that substrates bearing
benzylic or allylic N-α C–H can be oxidized.
[36]
[37]
4
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Entry for the Table of Contents
Photocatalytic amine oxidation. The visible-light promoted dehydrogenation of N-heterocycles is catalyzed by [Cp*Ir(dipyrido[3,2-
+
a:2’,3’-c]phenazine)Cl] under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially
yielded the monodehydrogenated product, accompanying H
2
O
2
generation. We surmise that this mechanism may be reminiscent of
flavin-dependent oxidases.
Institute and/or researcher Twitter usernames: WardGroupBS
5
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