Tunable System for Electrochemical Reduction of Ketones and Phthalimides

Article abstract of DOI:10.1002/cjoc.202100508

Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN₃ as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N₃/HN₃ cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.

Full text of DOI:10.1002/cjoc.202100508

Chinese Journal
of Chemistry
CJC
中 国 化 学 - An International Journal
Accepted Article
Title: Tunable System for Electrochemical Reduction of Ketones and Phthalimides
Authors: Yaxin Wang,* Jianyou Zhao, Tianjiao Qiao, Jian Zhang and Gong Chenb
This manuscript has been accepted and appears as an Accepted Article online.
This work may now be cited as: Chin. J. Chem. 2021, 39, 10.1002/cjoc.202100508.
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published online in Early View: http://dx.doi.org/10.1002/cjoc.202100508.
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Cite this paper: Chin. J. Chem. 2021, 39, XXX—XXX. DOI: 10.1002/cjoc.202100XXX
Tunable System for Electrochemical Reduction of Ketones and
Phthalimides
Yaxin Wang,*,a Jianyou Zhao,a Tianjiao Qiao,b Jian Zhang a and Gong Chenb
a State Key Laboratory Cultivation Base for TCM Quality and Efficacy, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing
210023 (China).
b State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071
(China).
Keywords
Electrochemistry | Reduction | Ketones | Phthalimides | Indolizidine
Main observation and conclusion
Herein we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without
the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode,
we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously
choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and
phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed
that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3·/HN3 cycle operated as a hydrogen atom
shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
Comprehensive Graphic Content
A) Selective reduction of ketones to alcohols or pinacols
B) Selective reduction of phthalimides to hydroxylactams or lactams
OH
N
R
AcOH (20 equiv)
OH
n
O
AcOH (20-100 equiv)
GF
CH3CN (solv)
CH3CN (solv)
Ar
R
R
O
GF
GF
GF
O
H
N
n
HO
R
Ar
OH
R
Ar
Ar
R
NaN3
(1.5 equiv)
NaN3
(1.5 equiv)
H
HCO2H (20 equiv)
CH3CN (solv)
n = 1-3
R
O
ketones
rt
rt
N
O
R = vinyl, aryl, hydroxyl
n
AcOH, HCO2H (solv, 1:1)
phthalimides
C) One-pot reduction/cyclization of phthalimide derivatives
H
O
O
N
N
O
HCOOH (solv)
O
HCOOH (solv)
O
O
GF
GF
R
GF
GF
82%
N
78%, dr = 1:1
NaN3
(1.5 equiv)
NaN3
(1.5 equiv)
n = 1, 2
R = vinyl, aryl, hydroxyl
O
O
rt
rt
HCOOH (solv)
HCOOH (solv)
N
N
O
O
56%
78%
*High versatility
*Mild conditions
GF = graphite felt
*Excellent specificity and efficiency
*Inexpensive electrodes
*Functional group compatibility
*Simple operation
*E-mail: 300500@njucm.edu.cn; 1120150254@nankai.edu.cn
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2021
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CAS,
Shanghai,
&
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Background and Originality Content
Results and Discussion
The reduction of carbonyl groups is undoubtedly one of the
most central organic transformations, and alcohols, pinacols,
and alkanes generated by these reactions are essential build-
ing blocks for the synthesis of drugs and other biologically ac-
tive molecules.1 Carbonyl groups are generally reduced with
hydrogen gas, metal hydrides, or other strongly reducing reac-
tive metals.2, 3 Despite the benefits of these well-established
methods, some of them require stoichiometric flammable re-
agents, special equipment, or complicated work-up proce-
dures, features that limit their substrate scope and their utility
for large-scale applications.1–4 Therefore, new methods that
are versatile and environmentally and user friendly are in de-
mand.
Recently, electrochemical methods have emerged as an attrac-
tive option for organic synthesis because they are operationally
safe, do not require stoichiometric external reductants or oxidants,
and are highly atom economical.5, 6 Direct reduction of carbonyl
compounds via electrolysis in the absence of stoichiometric reduct-
ants has been reported,7–9 however, most of transformations in
these reports involve metal electrodes, which usually serve as sac-
rificial anodes (Scheme 1A). In 2019, Cheng and co-workers devel-
oped a method for electrochemical hydrogenation of ketones to af-
ford alcohols or diaryl methanes by using reductive gas ammonia
as the hydrogen source with graphite felt electrodes; the anodic re-
action involves oxidation of an amide anion (Scheme 1B).10 Herein
we present our investigation of electrochemical reduction of car-
bonyl compounds with graphite felt electrodes and NaN3 as an elec-
trolyte. We discovered that carbonyl reduction, in a certain degree,
could be chemoselectively controlled to generate alcohols, pinacols,
or methylene groups by adjustment of the solvent and acidic addi-
tives without any reductive gases such as ammonia and hydrogen
(Scheme 1C).
Results
We began our studies with diphenyl methanone (1) as a model
substrate with graphite felt as electrodes in an undivided cell (Table
1). For our initial attempts, we tested the inexpensive and readily
available electrolyte NaCl, which functioned both to conduct elec-
tric current and to finish the anodic oxidation; in addition, we used
acetic acid (AcOH) to increase the reactivity of the carbonyl group.
Preliminary results indicated that constant-current electrolysis (20
mA) of 1 for 12 h with 1.5 equiv. of NaCl and 20 equiv. of AcOH in
CH3CN and H2O gave a 53% yield of alcohol 1o, along with a small
amount of pinacol 1p (entry 1). Encouraged by this result, we set
about to optimize the reaction conditions. First, screening of differ-
ent sodium salt electrolytes revealed that NaN3 had better solubil-
ity than other sodium salts and gave the highest yield of 1o.11 Next,
we investigated the influence of protic acids on the reaction out-
come. Interestingly, increasing the amount of AcOH increased both
the overall yield and the 1o/1p ratio (entries 2–6); specifically, the
use of 100 equiv. of AcOH resulted in a 70% isolated yield of 1o (78%
by NMR spectroscopy) (entry 6). Other carboxylic acids were much
less effective (entries 7 and 8), and mineral acids provided low
yields of both reduction products (entry 9).
Table 1 Optimization of conditions for reduction of ketone 1.
HO
Ph
Ph
OH
Ph
Ph
HO
H
O
GF(+) / GF(-) [20 mA]
(1.5 equiv)
+
Ph
Ph
Ph
Ph
NaCl or NaN3
acid (x equiv)
pinacol (p)
alcohol (o)
1
CH3CN (solv), air, rt, 12 h
1p
1o
Entry
Electrolyte / Acid
(equiv.)
Yield of
Yield of
1p (%)a
13
1o (%)a
1b
2
53
NaCl / AcOH (20)
NaN3 / AcOH (20)
NaN3 / AcOH (40)
NaN3 / AcOH (60)
NaN3 / AcOH (80)
NaN3 / AcOH (100)
NaN3 / t-BuCO2H (20)
NaN3 / i-PrCO2H (20)
NaN3 /
56
12
Scheme 1 Electrochemical reduction of carbonyl compounds.
3
57
12
A
) Pinacol-type reduction of ketones or aldehydes
4
64
10
5
69
10
O
HO
R
OH
R
6
78 (70c)
23
<10
6
R
R'
: Sn(+) / Pt(-);
R'
R'
: Pt(+) / Hg(-); : Sm(+) / Pt(-)
Mellah
7
Manchanayakage
Little
8
26
15
B
) Reduction of ketones or aldehydes to alcohols or diaryl methanes
9d
<10
<10
O
Pt(+) / Hg(-)
DMQ.2BF4
OH
:
Yadav
aq. H2SO4 or HCl (20)
NaN3 / HCO2H (20)
NaN3, no acid
R
R
10
11
12
13
<10
<10
93 (86b)
<10
O
OH
H
:
H
Cheng
GF(+) / GF(-)
or
Ar
R
gas
Ar
R
Ar
Ar'
NH3
no electric current
28 <10
AcOH (100), no NaN3
NaN3 / AcOH (100),
GF(+) / GF(−) were re-
placed with Pt(+) / Pt(−)
C
) This work: tunable reduction of ketones or phthalimides
GF(+) / GF(-)
(1.5 equiv)
NaN3
OH
AcOH (20-100 equiv)
a Reactions were carried out on a 0.5 mmol scale at room temperature (25
Ar
R
CH3CN (solv)
1
oC), and yields were determined from the H NMR spectra of the reaction
O
mixtures. GF = graphite felt. b 0.5 mL H2O was added to dissolve NaCl. c Iso-
lated yield. d The concentration of H2SO4 is 18.4 mol/L and the concentration
of HCl is 12 mol/L.
HO
R
Ar
OH
R
Ar
H (20 equiv)
HCO2
Ar
R
CH3CN (solv)
H
H
This latter result may be attributable to the evolution of hydrogen,
which is kinetically favored under strongly acidic conditions. Unex-
pectedly, when 20 equiv. of formic acid (HCO2H) was used, the
H (solv, 1:1)
AcOH, HCO2
Ar
R
*DMQ·2BF4 = dimethylquininium tetrafluoroborate; GF= graphite felt.
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Chin. J. Chem. 2021, 39, XXX－XXX

Running title
Chin. J. Chem.
HO
H
product selectivity was reversed; that is, the pinacol product was
favored over the alcohol (entry 10). A series of control experiments
proved that both the acidic additive and NaN3 were necessary (en-
tries 11 and 12). Platinum electrodes were evaluated and found to
give a low yield of the desired alcohol (entry 13).
O
GF(+) / GF(-) [20 mA]
R1 R2
(1.5 equiv)
R1 R2
NaN3
HOAc (100 equiv), CH3CN
10-22
alcohol (o)
A
Conditions
OH
OH
OH
OH
N
Ph
Ph
13o
(X=H, 80%a
Substrate Scope.
S
Selective reduction of diaryl ketones to alcohols or pinacols. We
explored the scope of the reaction by testing some diaryl ketones
under conditions A (for alcohols) or B (for pinacols) (Figure 1). In
general, para- and meta-substituted diaryl ketones (2–6) could be
selectively reduced to alcohols or pinacols in high yields under the
corresponding reaction conditions. However, coupling of ketyl radi-
cals derived from ortho-substituted diaryl ketones was hindered by
the steric bulk of the substituents, and thus only direct reduction
products (alcohols) were obtained (7o and 8o). A reaction of (4-
methoxyphenyl)(phenyl)methanone gave only alcohol 9o in moder-
ate yield, an outcome that may be attributable to oxidation of the
methoxyphenyl group.
(85%)
OH
(65%a
(80%)
(83%a
10o
11o
12o
)
)
OH
(X=F, 65%)
(X=Cl, 56%)
(X=Br, 50%)
14o
15o
16o
17o
18o
19o
OEt
)
a
X
(X=4-Cl, 71% )
(X=3,4-di-Cl, 81%a
O
X
)
OH
O
O
MeO2C
Ph
CO2Bn
Ph
OMe
OEt
OH
(60%a
OH
(76%a
ketoprofen
(67%, dr = 1:1.9)
22o
21o
20o
)
)
Reactions were conducted on a 0.5 mmol scale at room temperature under
air. a 20 equiv. of AcOH was used.
HO OH
O
GF(+) / GF(-) [20 mA]
HO
Ar1
H
GF(+) / GF(-) [20 mA]
Ar1
Ar1
(1.5 equiv)
(1.5 equiv)
Ar1
Ar2
Ar2
NaN3
NaN3
Ar2 Ar2
Figure 2. Selective reduction of other carbonyl compounds to alcohols.
HOAc (100 equiv)
CH3CN (solv)
HCOOH (20 equiv)
CH3CN (solv)
2-9
pinacol (p)
alcohol (o)
A
B
Conditions
Conditions
Selective reduction of phthalimides. Phthalimides with a variety
of functional groups also efficiently underwent selective reduction
under conditions A’ to afford hydroxylactams 23o, 24o, 27o, and
28o. These results prompted us to evaluate the possibility of C–C
bond formation via an acyl-iminium ion (Figure 3). We discovered
that by changing the reaction medium from CH3CN/AcOH to HCO2H,
we could obtain various pharmaceutically important indolizidine
OH
OH
Cl
Ph
pinacol (p)
pinacol (p)
(12%) [
(83%) [
F
F
+
+
(72%)
(6%)
(8%)
(85%) [
[
(65%)
(7%)
+
+
2o
2o
2p
A
]
B
]
3o
3o
3p
3p
A
B
]
]
2p
scaffolds by means of
phthalimide derivatives with a tethered nucleophile (vinyl, aryl, or
hydroxyl) (23c–26c)12, 13
a one-pot reduction/cyclization of
OH
OH
Br
Ph
Ph
pinacol (p)
pinacol (p)
(12%) [
.
Cl
Moreover, we were pleased to find that when 1:1 (v/v)
HCO2H/AcOH was used as solvent, reactions of imides gave lac-
tams12. Specifically, electrochemical reactions of various imides
with 1.5 equiv. of NaN3 gave the corresponding lactams (23a, 24a,
27a, and 28a) in moderate to good yields (Figure 3). The
phthalimide tether profoundly influenced the yield, with longer
tethers favoring the lactam products (compare the yields of 27a and
28a).
(77%)
(7%)
+
+
(8%) [
(82%) [
(67%)
(5%)
+
+
5o
5o
5p
5p
A
B
4o
4o
4p
A
B
]
]
]
]
(86%) [
4p
OH
OH
F
Ph
Ph
pinacol (p)
pinacol (p)
(0%) [
CF3
+
+
(76%)
(8%)
(6%)
(82%) [
[
(56%)
(50%)
+
+
6o
6o
6p
6p
A
B
7o
7o
7p
7p
A
B
]
]
]
]
(0%) [
OH
OH
Cl
Ph
pinacol (p)
(0%) [
Ph
pinacol (p)
(0%) [
Cl
8o
8o
OMe
+
+
(88%)
(85%)
+
+
8p
8p
A a
]
(43%)
(41%)
9o
9o
9p
9p
A
]
(0%) [
(0%) [
B
]
B
]
Reactions were conducted on a 0.5 mmol scale at room temperature under
air. a 20 equiv. of AcOH was used.
Figure 1. Reduction of diaryl ketones to alcohols or pinacols.
Selective reduction of other carbonyl compounds to alcohols.
Additionally, various aryl alkyl ketones (10 and 11), heteroaryl aryl
ketones (12 and 13), aryl aldehydes (14–16), and α-ketoesters (17–
21) were smoothly reduced to the corresponding alcohols under
conditions A (Figure 2). Pyridine and thiophene rings, a benzyl
group, halogen atoms, and esters were tolerated. Moreover, we
were delighted to find that benzyl-protected ketoprofen (22) could
also be reduced efficiently to the corresponding alcohol (22o). In-
terestingly, even when NaN3 was replaced with NaCl in these reac-
tions, the alcohol products were obtained in similar yields.
Chin. J. Chem. 2021, 39, XXX－XXX
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First author et al.
Report
O
H
X
N
O
HO
H
H H
R
R
GF(+) / GF(-) [20 mA]
GF(+) / GF(-) [20 mA]
N
Ph
Ph
Ph
(1.5 equiv)
NaN3
or
(1.5 equiv)
N
N
N
N
NaN3
alcohol (o)
cyclization product (c)
lactam (a)
A'a
Dc
Conditions
Cb
A' or D
conditions
,
,
O
O
29-32
substrate
A'a
Cb
Dc
H
H
H H
Conditions
Conditions
Conditions
OH
OH
Ph
N
HOAc (20 equiv)
CH3CN (solv)
HCO2H (solv)
HCO2H/HOAc
(solv, 1:1)
N
Ph
Ph
N
Ph
H
(85%)
(82%)
+
+
(0%) [
(0%) [
(86%)
(80%)
+
+
(0%) [
(0%) [
O
H
H
N
A'a
Db
30o
30o
30a
30a
A'a
Db
]
29o
29o
29a
29a
HO
H
N
]
O
]
]
N
O
H
H
OH
OH
PhthN
H H
N
N
O
(70%)
O
Ph
Ph
23a
(87%)
(78%, dr = 1:1)
23
23o
23c
(17%)]
Cl
Cl
N
N
23o
& [
(15%c
(10%c
(78%c
(79%c
(20%)
(22%)
+
(75%) [
(70%) [
Ph
A'a
Db
32o
32o
32a
32a
A'a
Db
H
H
N
31o
31o
31a
31a
)
)
+
) [
) [
]
]
H
Ph
+
HO
+
]
]
Ph
N
N
0.5 mmol of substrate, 1.5 equiv. a Reaction conditions A’: 20 equiv. of AcOH,
CH3CN (4.5 mL). b Reaction conditions D: HCO2H (4.0 mL), AcOH (4.0 mL). c
Crude 1H-NMR yield.
PhthN
O
O
(50%)
O
24a
(85%)
(82%)
(30%)]
24
24o
24c
24o
& [
Ph
O
Figure 4. Reduction of pyridyl aryl ketones.
PhthN
N
O
O
(56%)
25
25c
Mechanistic Studies.
O
N
To determine the mechanism of these reduction reactions, we
carried out a series of control experiments (Scheme 2). First, when
reduction of diphenyl ketone 1 was conducted with deuterated ace-
tic acid (D4-HOAc), alcohol 1o’ (99% deuterium incorporation) was
isolated in 65% yield (Scheme 2A),14 indicating that AcOH was the
hydrogen source. Moreover, reaction of radical clock substrate 33
gave ring-opening product 33x in 28% isolated yield, suggesting that
a benzyl radical was involved in the reaction (Scheme 2B). In addi-
tion, cathodic cyclic voltammetry analysis of a mixture of 1 and
AcOH or HCO2H revealed that the absolute value of the reduction
potential of the diphenyl ketone was lower under weakly acidic con-
ditions than in CH3CN alone; the reduction peak of 1 was observed
at −1.3 V in CH3CN (vs SCE [saturated calomel electrode]), whereas
the reduction peak in CH3CN/AcOH was at −1.1 V and that in
CH3CN/HCO2H) was at −1.0 V (Scheme 2C).14
HO
PhthN
O
(78%)
26
26c
Ph
Ph
H
Ph
HO
H
H
N
N
PhthN
O
(73%)
O
27a
& [
(85%)
(15%)]
27
27o
27o
H
HO
H
H
N
Ph
Ph
Ph
N
PhthN
O
O
(30%)
(80%)
28a
& [
(60%)]
28o
On the basis of the results of our mechanistic studies, we pro-
pose the mechanism outlined in Scheme 2D. First, the carbonyl
group is protonated and then reduced by a single electron at the
cathode to generate radical II. This species can either be further re-
duced to alcohol V (path A) or undergo radical dimerization to fur-
nish pinacol product III (path B). In the presence of AcOH, the re-
duction of II occurs via either a proton/electron transfer sequence
or by transfer of a hydrogen atom from HN3 generated in situ.15 Our
initial screening of sodium salt electrolytes demonstrated that
NaN3 can be replaced with NaCl for the reduction of ketones to al-
cohols, indicating radical II is more likely to undergo proton/elec-
tron transfer to give alcohol V rather than hydrogen transfer with
HN3. When HCO2H is present in the medium, it may serve as the
more reactive reductant, preventing further reduction of II, thus re-
sulting in the formation of dimerization products. For reduction to
methylene compounds, we envisaged that at high proton concen-
trations, carbocation VI is generated by protonation and subse-
quent dehydration. Carbocation VI can be reduced by an electron
from the cathode to produce radical VII, which may undergo a hy-
drogen atom transfer reaction with HN3 to generate VIII and N3·.
N3· Subsequent hydrogen abstraction from HCO2H provides radical
IX, which undergoes anodic oxidation to give CO2 and a proton.16
With HN3 as a hydrogen atom donor and N3· as a hydrogen atom
abstractor, the N3·/HN3 cycle operates as a hydrogen atom shut-
tle,15 while HCO2H serves as the terminal oxidant. In this process,
NaN3 is a necessary reagent.
28
28o
0.5 mmol of substrate. a Conditions A’: 20 equiv. of AcOH, CH3CN (4.5 mL). b
c
Conditions C: HCO2H (5.0 mL). Conditions D: HCO2H (4.0 mL), AcOH (4.0
mL).
Figure 3. Selective reduction of phthalimides.
Reduction of pyridyl aryl ketones. Interestingly, in reactions of
phenyl pyridinyl ketones (Figure 4), the location of the nitrogen
atom played a substantial role in the outcome of the reduction. Un-
der conditions A’ and D, phenyl(pyridin-4-yl)methanone mainly
gave the corresponding diaryl methanes, whereas phenyl(pyridin-
2-yl)methanone and phenyl(pyridin-3-yl)methanone gave the cor-
responding alcohols; these results indicate that product selectivity
was controlled by the substrate itself rather than by the reaction
conditions. Finally, we found that the reduction of phenyl(pyridin-
2-yl)methanone to alcohol could easily be carried out on a gram
scale.11
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Chin. J. Chem. 2021, 39, XXX－XXX

Running title
Chin. J. Chem.
Scheme 2. Mechanistic studies.
provided a valuable tool for direct construction of indolizidine scaf-
folds, which are found in natural products and drug molecules. Fur-
ther mechanism studies of this chemistry and exploration of its ap-
plications for pharmaceutical synthesis are ongoing in our laborato-
ries.
A
B
C
1
reduction of using D4-HOAc
) Deuteration
HO
H/D
Ph
O
GF(+) / GF(-) [20 mA]
(1.5 equiv)
Ph
NaN3
Ph
Ph
1o'
D4-HOAc (100 equiv)
CH3CN (4.5 mL)
12h
1
65%;
:
Isolated yield
Deuteration ratio
Experimental
>99%
(0.5 mmol)
1o':
The flask was equipped with two rubber plugs, graphite felt (2
cm×1 cm×0.5 cm) as anode and cathode. Two electrodes were sep-
arated with a Teflon film. The graphite felt anode and cathode at-
tached to a platinum wire. A Teflon wire tied around two electrodes.
Substrate (0.5 mmol, 1.0 equiv) and acid (AcOH or HCOOH) (10.0
mmol, 20.0 equiv) were first dispersed CH3CN (4.5 mL) stirred for 5
min at room temperature. NaN3 (49.0 mg, 0.75 mmol, 1.5 equiv)
was then added. The reaction mixture was stirred and electrolyzed
with a constant current of 20 mA at room temperature (25 oC). After
the reaction completed as monitored with TLC, the solvents were
removed in vacuo and the residue was purified by silica gel flash
chromatography to give the desired products.
33
) Radical clock experiment of compound
HO
Ph
OH
Ph
OH
Ph
O
O
GF(+) / GF(-) [20 mA]
(1.5 equiv)
Ph
33x (
Ph
NaN3
HOAc (100 equiv)
CH3CN (4.5 mL)
6h
33
(0.5 mmol)
33o (
28%)
35%)
33p (
8%)
a
) CV analysis of species in reactions
Supporting Information
The supporting information for this article is available on the
WWW under https://doi.org/10.1002/cjoc.2021xxxxx.
D
) Proposed reaction pathways
OH
R'
Reaction on cathode
IV
R
e
+ H+
SET
e
OH
R'
OH
SET
Path A
O
Acknowledgement
+ H+
R'
R'
R
R
R
H
I
II
We are grateful to the National Science Foundation of China (no.
22001128), the National Science Foundation of Jiangsu Province (no.
BK20200847), and the National Science Foundation of Nanjing Uni-
versity of Chinese Medicine (no. NZY22001128).
V
H+
Path B
H2O
HO
R
OH
R
R'
R
R'
R'
H
VI
III
References
e
SET
R'
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H
H
H
transfer (HN3
)
R'
R
Path C
R
VII
VIII
Reaction on anode and role of NaN3
H
H+
H atom shuttle
terminal
N3
HN3
HO
NaN3
O
O
- e
+
H+
CO2
H atom donor
HO
H
SET
IX
a In the cyclic voltammetry experiment, the concentrations of 1 and the acid
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Chin. J. Chem. 2021, 39, XXX－XXX
© 2021 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
www.cjc.wiley-vch.de

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(The following will be filled in by the editorial staff)
Manuscript received: XXXX, 2021
Manuscript revised: XXXX, 2021
Manuscript accepted: XXXX, 2021
Accepted manuscript online: XXXX, 2021
Version of record online: XXXX, 2021
Chin. J. Chem. 2021, 39, XXX－XXX
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First author et al.
Report
Entry for the Table of Contents
Title
Author, Corresponding Author,* Author
Chin. J. Chem. 2021, 39, XXX—XXX. DOI: 10.1002/cjoc.202100XXX
OH
AcOH (20-100 equiv)
CH3CN (solv)
Ar
R
O
HO
R
Ar
OH
R
Ar
GF
GF
H (20 equiv)
HCO2
Ar
R
CH3CN (solv)
NaN3
(1.5 equiv)
ketones
phthalimides
rt
H
H
Ar
R
H (solv, 1:1)
AcOH, HCO2
*High versatility
* Mild conditions
*Excellent specificity and efficiency
*Functional group compatibility
* Inexpensive electrodes
* Simple operation
Text for Table of Contents.
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© 2021 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
Chin. J. Chem. 2021, 39, XXX－XXX