Bu 4 NI-Catalyzed C-C Bond Cleavage and Oxidative Esteri??cation of Allyl Alcohols with Toluene Derivatives

Article abstract of DOI:10.1055/s-0039-1690105

A novel oxidative esterification of 1-arylprop-2-en-1-ols with toluene derivatives catalyzed by tetrabutylammonium iodide (TBAI) is reported. The optimization of the reaction conditions illustrates that each of experiment parameters including the catalyst, solvent, and oxidant is significant for present oxidative functionalization. This metal-free protocol has a broad substrate scope including the halogen groups for further functionalization and enriches the reactivity profile of allyl alcohol and toluene derivatives. In addition, this protocol represents a new transformation of allyl alcohol involving C-C bond cleavage and C-O bond forming.

Full text of DOI:10.1055/s-0039-1690105

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–H
paper
A
en
Y. Chen et al.
Paper
Synthesis
Bu4NI-Catalyzed C–C Bond Cleavage and Oxidative Esterification
of Allyl Alcohols with Toluene Derivatives
Yaoyao Chen §
Chengliang Li §
Yongmei Cui*
Mingming Sun
Xueshun Jia*
Jian Li*
O
OH
O
TBAI/TBHP
R2
+
Me Ar
+
Ar
R1
O
R1
R2
O
Ar
MeCN (0.5 M)
24 examples
54–94% yield
Unusual C–C Bond Cleavage of Allyl Alcohol
Readily Available Toluene Derivative as Precursor
Department of Chemistry, Center for Supramolecular Chemistry
and Catalysis, College of Sciences & Institute for Sustainable Energy,
Shanghai University, 99 Shangda Road, Shanghai 200444,
P. R. of China
ymcui@shu.edu.cn
xsjia@mail.shu.edu.cn
lijian@shu.edu.cn
§ These authors contributed equally to this work.
Received: 26.04.2019
Accepted after revision: 10.06.2019
Published online: 16.07.2019
modern synthesis and academic research because of its ver-
satility.4 As shown in Scheme 1, allyl alcohol or its masked
versions could construct versatile compounds via allylic
substitution (Scheme 1, path a and c).5 For instance, Zhang
and co-authors disclosed a series of allylic alkylation cata-
lyzed by Pd5a,b or dual Ir/Cu5c affording the valuable asym-
metric compounds. Other related transformations were also
intensively investigated by Loh, Li, Trost, and Hartwig
group.6 Moreover, regioselective reduction of alcohol unit
of allyl alcohol skeleton could afford the valuable alkenes
(Scheme 1, path b and d).7 In 2006, Das group reported I2-
mediated reduction of allyl alcohol using NaBH4 as reducing
agent.7a Of late, Lipshutz group also obtained trisubstituted
alkene via copper hydride reductions of allyl alcohol.7c In
addition, multiple oxidation could occur due to the hydroxyl
group (Scheme 1, path e).8–10 Recently, Coelho,8a Lawrence,8b
and Rao group8c achieved selective carbonylation of hydrox-
yl of allyl alcohol using 5-iodane reagents as oxidant, re-
spectively. Interestingly, Zhao group reported an organose-
lenium-catalyzed synthesis of ,-unsaturated aldehydes
from allyl alcohol involving the migration of double C=C
bond.9 Despite these advances, further exploration of allyl
alcohol skeleton is still highly desired. In particular, due to
diverse products, new oxidative process affording valuable
compound is considerably attractive.
DOI: 10.1055/s-0039-1690105; Art ID: ss-2019-h0247-op
Abstract A novel oxidative esterification of 1-arylprop-2-en-1-ols with
toluene derivatives catalyzed by tetrabutylammonium iodide (TBAI) is
reported. The optimization of the reaction conditions illustrates that
each of experiment parameters including the catalyst, solvent, and oxi-
dant is significant for present oxidative functionalization. This metal-
free protocol has a broad substrate scope including the halogen groups
for further functionalization and enriches the reactivity profile of allyl
alcohol and toluene derivatives. In addition, this protocol represents a
new transformation of allyl alcohol involving C–C bond cleavage and
C–O bond forming.
Key words esterification, allyl alcohol, toluene derivative, oxidative
coupling, C–H activation
Among the cross-coupling reactions, esterification is an
essential conversion in synthetic field.1 The fascinating pro-
file of esterification that differs from other transformation
is its versatile application in academia and industry. In most
cases, esterification derives largely from the alcohols and
available carboxylic acids.2 However, the usual protocols of
esterification with aldehydes/alcohols as acyl sources re-
quire carboxylation in advance. On the other hand, direct
esterification from aldehydes is attractive with the assis-
tance of transition-metal reagents.3 Except for the acyl
sources, the other partner of esterification always involves
the aryl/alkyl halogen or alcohol, which is usually prepared
from hydrocarbon in advance or requires transition metal
reagents as crucial catalyst. Furthermore, these multistep
processes are inefficient with respect to the large amount of
resultant waste. With the increasing demand of environ-
mentally friendly organic processes, therefore, allyl alcohol
skeleton is extensively used as synthetic intermediate in
With simple and abundant profile, toluene and its de-
rivatives have found versatile application in modern syn-
thesis.11–13 Among these valuable transformations, func-
tionalization of benzylic Csp3–H of toluene derivatives was
particularly important because of its ability to efficiently
afford the direct construction of the carbon–carbon/hetero-
atom bond.12 In our previous work, we have disclosed the
coupling reaction of toluene derivatives with carbonyl com-
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
Y. Chen et al.
Paper
Synthesis
Table 1 Optimization of the Reaction Conditionsa
Classical ways:
R
R1
TM, [H]
TM or SN2
path a
O
O
OH
R1
OPG
R2
path b
conditions
R2
R1
+
Me Ph
2a
+
Ph
Me
O
Ph
Ph
O
R2
or
AcCl, TsCl etc.
Ph
or
R1
4a
1a
3a
TM, [H]
TM or SN2
path c
R1
R
R1
R2
R2
OH
R2
[O]
path d
Entry
Catalyst
Oxidant
Solvent
Yield (%)b
0
path e
1
2
CuI
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
H2O2
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
EtOAc
PhCl
R
R1
R1
R1
CuBr
FeCl3
FeBr3
FeBr2
TBAB
NIS
<5 (3a) + <5 (4a)
R2
O
3
0
R2
O
R2
O
4
35 (3a) + 19 (4a)
This work
O
5
22 (3a) + 5 (4a)
OH
+
R1
O
Ar
6
0
R1
R2
TBAI/TBHP
MeCN, 80 °C
O
+
7
0
R2
O
Ar
Ar Me
8
I2
0
9
KI
trace
Scheme 1 Diverse conversion of allyl alcohol and its derivatives
10
11
12
13
14
15
16
17
18
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
TBAI
–
71 (3a) + 75 (4a)
61 (3a) + 54 (4a)
pounds, isocyanides, and olefins, respectively.14 And a care-
ful literature survey illustrated that the cross-coupling be-
tween allyl alcohols and toluene derivatives via Csp3–H
functionalization was still underexploited. As a continua-
tion of our previous investigation,14,15 herein we report the
reaction between allyl alcohol and toluene derivative to-
wards a new esterification process.
Initially, we used 1-phenylprop-2-en-1-ol (1a) and tolu-
ene (2a) as the model substrates in MeCN to optimize the
reaction conditions. As described in Table 1, poor perfor-
mance was observed when using copper salt as the catalyst
and TBHP as the oxidant (Table 1, entries 1, 2). To our de-
light, iron salt as catalyst increased the yields up to 35% for
3a and 19% for 4a (entries 3–5). No desired product was
achieved when other metal-free catalysts, such as TBAB,
NIS, or I2 were used (entries 6–8). To our delight, 71% of 3a
and 75% of 4a were obtained when tetrabutylammonium
iodide (TBAI) was used as the catalyst (entry 10). Then, oth-
er solvents including EtOAc, PhCl, and DCE were screened,
which did not lead to any further improvement (entries 11–
14). After that, oxidants such as H2O2, (t-BuO)2 and K2S2O8
were also examined (entries 15–17).
With the optimal conditions in hand, we next investi-
gated the substrates scope of this present transformation.
First, different substituents on the arene ring of 1-arylprop-
2-en-1-ol were evaluated. As shown in Scheme 2, electron-
donating groups on both ortho- and para-positions of the
aromatic ring of 1-arylprop-2-en-1-ol were well tolerated
(Scheme 2, → 3b–d and 3h,i). Furthermore, halogen atoms
(Scheme 2, → 3e–g and 3j) for further functionalization
were well tolerated affording moderate to good yields. It
was also worthy to note that the simultaneous esterifica-
tion of toluene was achieved in moderate yields (→ 4a). Ad-
ditionally, the aryl group in allyl alcohol seemed to be nec-
essary since no desired products were detected when the
trace
<10
trace
0
DCE
THF
MeCN
MeCN
MeCN
MeCN
(t-BuO)2
K2S2O8
TBHP
trace
0
0
a Reaction conditions: 1-phenylprop-2-en-1-ol (1a; 1.0 mmol), toluene (2a;
4.0 mmol), catalyst (0.1 equiv), oxidant (6.0 equiv), solvent (2.0 mL),
80 °C, 24 h, in a sealed tube.
b Yields of product after silica gel chromatography.
aryl group was replaced by aliphatic groups such as ethyl
and isopropyl ones. Moreover, 1k (R1 = Ph, R2 = 3-MeOPh)
and 1l (R1 = Ph, R2 = Me), as different substrates to terminal
olefins, were tested for the universality of allyl alcohol part.
Next, we examined many toluene derivatives for the
present oxidative esterification. As described in Scheme 3,
employment of individual substrate 2 bearing chlorine or
bromine atom at ortho-, meta-, or para- position could
achieve the product in good yield for further functionaliza-
tion (Scheme 3, → 3p,q, 3s,t and 3v,w). Moreover, electron-
donating groups, such as alkyl (→ 3m,n, 3r, and 3u) and
methoxy (Scheme 3, → 3o), were also suitable substituents
for the current transformation. In addition, 2-methylnaph-
thalene was examined for the extended investigation. Si-
multaneously, benzyl acetates 4m–x bearing diverse sub-
stituents on the arene ring were successfully synthesized in
good yields, which afforded an opportunity for functional-
ized benzyl alcohols from toluene derivatives via direct C–H
activation. Unfortunately, no reaction occurred when alky-
larenes such as ethylbenzene and ibuprofen were used as
components.
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H

C
Y. Chen et al.
Paper
Synthesis
O
OH
O
TBAI (10 mol%)
TBHP (6 equiv)
TBAI
(10 mol%)
TBHP
R2
O
+
R1
O
Ar +
Me Ar
2
O
Ph
Ph
OH
O
Ar
MeCN (0.5 M)
80 °C, 24 h
(6 equiv)
R2
R1
R2
+
R1
O
Ph
+
Me Ph
2a
O
Ph
4
1a
3
MeCN (0.5 M)
80 °C, 24 h
4
3
O
1
O
O
O
O
Ph
O
Ph
O
O
3m, 67%
3n, 61%
3o, 54%
tBu
tBu
Me
OMe
OMe
+
+
+
O
Ph
O
Ph
+
O
AcOBn
O
O
4a, 75%
3a, 71%
+
4a, 72%
3b, 68%
Me
Me
O
Me
O
Me
O
O
O
O
4m, 62%
Me 4n, 57%
4o, 60%
Ph
O
Ph
O
O
O
Me
MeO
tBu
3c, 61%
4a, 55%
3d, 59%
+
4a, 60%
+
Ph
O
Ph
O
O
Ph
O
O
3p, 72%
3q, 73%
3r, 72%
Cl
Br
O
Ph
+
O
Ph
+
+
+
+
O
O
3f, 81%
O
Me
4a, 76%
4a, 55%
Cl
3e, 75%
4a, 73%
F
Me
O
Me
Ph
O
Me
O
O
Me
O
4p, 75%
Br
4q, 74%
4r, 70%
Cl
O
Ph
O
Ph
O
O
Cl
Cl
4a, 65%
4a, 58%
O
Br
Br
3g, 73%
3h, 54%
O
O
Me
Me
Ph
O
Ph
Cl
O
OMe
O
3t, 60%
3s, 65%
3u, 77%
O
Ph
O
Ph
+
+
+
O
O
3j, 60%
4a, 48%
O
Br
+
+
3i, 58%
Me
O
Me
O
Me
O
O
O
4u, 80%
4s, 66%
4t, 65%
Me
O
Ph
MeO
+
4b, 52%
O
Ph
+
3l (3a) 55%
4c, 68%
3k (3a), 45%
O
O
O
O
O
O
Scheme 2 Scope of the reaction with respect to the substrate 1. Re-
agents and conditions: 1 (1.0 mmol), 2a (4.0 equiv), TBAI (0.1 equiv),
TBHP (6.0 equiv), MeCN (2.0 mL), 80 °C, 24 h. Isolated yields after silica
gel chromatography are shown.
Cl
Cl
Br
Ph
Ph
Ph
3x, 70%
3v 83%
3w, 78%
+
+
+
O
O
O
Br
Me
O
Me
O
Me
O
Preliminary mechanistic experiments were subsequent-
ly investigated to have a deeper insight into the present oxi-
dative esterification. As shown in Scheme 4, 1-phenylpro-
pane-1,2-diol (5) and 1-phenylpropane-1,2-dione (6) react-
ed with toluene to access the desired ester (Scheme 4, eq 1
and eq 2) in moderate yields, which suggested that these
species are possible intermediates. Then, benzoic acid (7)
and acetic acid (8) were treated with 1-methoxy-4-methyl-
benzene (2o) under the standard conditions, respectively.
As a result, esterification could also proceed well (Scheme
4, eq 3 and eq 4). These results imply that carboxylic acids,
derived from allyl alcohol via stepwise oxidation, might
also be involved in this present conversion.
According to the above-mentioned experiments and
previous literature,16–22 a plausible mechanistic process is
proposed to explain the oxidative conversion of allyl alco-
hols. As described in Scheme 5, allyl alcohol 1a is first oxi-
dized to the ,-unsaturated ketone A,16 which is converted
to B via epoxidation process.17 Then, the 1,2-dione com-
pound C is formed through the thermal rearrangement.18
4w, 80%
4v, 84%
4x, 68%
Scheme 3 Scope of the reaction with respect to the substrate 2. Re-
agents and conditions: 1a (1.0 mmol), 2 (4.0 equiv), TBAI (0.1 equiv),
TBHP (6.0 equiv), MeCN (2.0 mL), 80 °C, 24 h. Isolated yields after silica
gel chromatography are shown.
As reported previously, 1,2-dione compound could be con-
verted to carboxylic acids D and E with the assistance of ox-
idant via C–C bond cleavage.19 On the other hand, toluene is
oxidized by TBHP to benzyl cation G through the radical in-
termediate F.20–22 Finally, the nucleophilic electrophilic re-
action between D and G provides the product 3a, mean-
while, coupling between E and G yields the product 4a.
In summary, we have developed an efficient protocol for
the oxidative esterification of allyl alcohol with toluene de-
rivatives. This protocol represents a new reactivity profile
of allyl alcohol under oxidative conditions. It is proposed to
proceed through C–C bond cleavage of 1-arylprop-2-en-1-
ol and simultaneous benzylic Csp3–H activation of toluene
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H

D
Y. Chen et al.
Paper
Synthesis
plished by column chromatography packed with silica gel. Unless oth-
erwise stated, all reagents were commercially purchased and used
without further purification.
OH
TBAI (10 mol%)
Me
Ph
2a
3a, 51%
+
+
+
4a, 54%
4a, 61%
(1)
(2)
TBHP (6 equiv)
MeCN, 80 °C, 24 h
OH
5
Esterification of Allyl Alcohols 1 with Toluene Derivatives 2; Gen-
eral Procedure
O
TBAI (10 mol%)
Me
2a
Ph
Ph
Me
3a, 69%
+
Under air atmosphere, a sealable reaction tube equipped with a mag-
netic stir bar and covered with a rubber septum was charged with al-
cohol compound 1 (1.0 mmol), toluene derivative 2 (4.0 mmol), and
Bu4NI (36.9 mg, 10 mol%) in MeCN (2.0 mL). To this mixture was add-
ed TBHP (70% wt/v in H2O, 6.0 equiv) at r.t. The rubber septum was
then replaced by a Teflon-coated screw cap, and the reaction vessel
was placed in an oil bath at 80 °C for 24 h. After the completion of the
reaction (monitored by TLC), the mixture was cooled to r.t. The result-
ing solution was poured into a mixture of sat. aq Na2S2O3 (5 mL) and
sat. aq NaHCO3 (5 mL), and extracted with EtOAc (2 ×). The combined
organic layers were dried (anhyd Na2SO4) and the solvents were re-
moved in vacuo. The residue was purified by flash chromatography
on silica gel (eluent: PE/EtOAc) to give the desired product.
TBHP (6 equiv)
MeCN, 80 °C, 24 h
O
6
Me
O
O
TBAI (10 mol%)
+
+
Ph
O
OH
(3)
(4)
TBHP (6 equiv)
MeCN, 80 °C, 24 h
3o, 86%
7
OMe
OMe
2o
O
TBAI (10 mol%)
3o, 42%
2o
OH
TBHP (6 equiv)
MeCN, 80 °C, 24 h
8
Scheme 4 Preliminary mechanistic investigation
Benzyl Benzoate (3a)12a
Colorless oil; yield: 150 mg (71%).
TBAI + TBHP
O
OH
O
O
1H NMR (500 MHz, CDCl3):  = 8.18 (d, J = 7.5 Hz, 2 H), 7.61 (t, J = 7.5
Hz, 1 H), 7.54 (d, J = 8.0 Hz, 2 H), 7.48 (dd, J = 12.5, 7.5 Hz, 4 H), 7.41 (d,
J = 7.0 Hz, 1 H), 5.45 (s, 2 H).
O
I2
in situ
Ph
Ph
Ph
H
TBHP
A
H
1a
B
13C NMR (125 MHz, CDCl3):  = 166.46, 136.19, 133.12, 130.24, 12.80,
128.70, 128.48, 128.34, 128.27, 66.76.
O
O
O
H
H
H
thermal
+
O
Me
OH
Ph
OH
Ph
rearrangement
D
O
TBHP
C
E
Benzyl 4-Methylbenzoate (3b)23
O
Colorless oil; yield: 154 mg (68%).
D
1H NMR (500 MHz, CDCl3):  = 8.03 (d, J = 8.1 Hz, 2 H), 7.49 (d, J = 7.3
Hz, 2 H), 7.43 (t, J = 7.4 Hz, 2 H), 7.40–7.35 (m, 1 H), 7.29–7.24 (m, 2
H), 5.40 (s, 2 H), 2.43 (s, 3 H).
Ph
O
CH2
CH2
O
3a
TBAI
2a
O
TBHP
E
13C NMR (125 MHz, CDCl3):  = 166.51, 143.75, 136.28, 129.79,
F
G
Me
O
129.15, 128.62, 128.22, 128.16, 127.46, 66.52, 21.68.
4a
Scheme 5 Possible mechanism for esterification of allyl alcohols with
toluene derivatives
Benzyl 4-(tert-Butyl)benzoate (3c)24
Colorless oil; yield: 163.5 mg (61%).
1H NMR (500 MHz, CDCl3):  = 8.11 (d, J = 8.0 Hz, 2 H), 7.50 (d, J = 8.5
Hz, 4 H), 7.43 (t, J = 7.0 Hz, 2 H), 7.38 (t, J = 7.5 Hz, 1 H), 5.43 (s, 2 H),
1.39 (s, 9 H).
13C NMR (125 MHz, CDCl3):  = 166.46, 156.72, 136.39, 129.73,
128.65, 128.23, 128.17, 127.50, 125.45, 66.51, 35.12, 31.20.
derivatives. This current transformation demonstrates a
wide substrate scope and tolerates carbon–halogen bonds
for further functionalization.
Benzyl 4-Methoxybenzoate (3d)12a
NMR spectra were recorded on Bruker AC-500 spectrometer (500
MHz for 1H NMR and 125 MHz for 13C NMR) with CDCl3 as the solvent
and TMS as internal reference. 1H NMR spectral data were reported as
follows: chemical shift (, ppm), multiplicity, integration, and cou-
pling constant (Hz). 13C NMR spectral data were reported in terms of
the chemical shift. Standard abbreviations were used to indicate mul-
tiplicities. Low-resolution mass spectra were obtained on a Shimadzu
LCMS-2010EV spectrometer in ESI mode. High-resolution mass spec-
tra (HRMS) were recorded on a Bruker Daltonics, Inc. APEXIII 7.0 TES-
LA FTMS instrument. Melting points were obtained on an X-4 digital
melting point apparatus without correction. Chemical yields are re-
ferred to pure isolated product. Purification of products was accom-
Colorless oil; yield: 143 mg (59%).
1H NMR (500 MHz, CDCl3):  = 8.10 (d, J = 9.0 Hz, 2 H), 7.50 (d, J = 7.5
Hz, 2 H), 7.43 (t, J = 7.5 Hz, 2 H), 6.95 (d, J = 8.5 Hz, 1 H), 5.39 (s, 2 H),
3.86 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 166.20, 163.50, 136.39, 131.79,
128.62, 128.20, 128.15, 122.58, 113.69, 66.42, 55.42.
Benzyl 4-Fluorobenzoate (3e)24
Colorless oil; yield: 173 mg (75%).
1H NMR (500 MHz, CDCl3):  = 8.14 (dd, J = 9.0, 5.5 Hz, 2 H), 7.51 (d, J =
7.5 Hz, 2 H), 7.45 (t, J = 7.5 Hz, 2 H), 7.42–7.38 (m, 1 H), 7.12 (t, J = 8.5
Hz, 2 H), 5.42 (s, 2 H).
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H

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Y. Chen et al.
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Synthesis
13C NMR (125 MHz, CDCl3):  = 166.85, 165.84 (J = 251.25 Hz), 136.08,
132. 32 (J = 10.0 Hz), 128.70, 128.39, 128.30, 126.50 (J = 10.0 Hz),
115.55 (J = 22.5 Hz), 66.86.
4-Methoxybenzyl Benzoate (3o)26
Colorless oil; yield: 131 mg (54%).
1H NMR (500 MHz, CDCl3):  = 8.11 (d, J = 8.0 Hz, 2 H), 7.57 (d, J = 7.5
Hz, 1 H), 7.47–7.43 (m, 4 H), 6.95 (d, J = 8.5 Hz, 2 H), 5.34 (s, 2 H), 3.83
(s, 3 H).
Benzyl 4-Chlorobenzoate (3f)24
Colorless oil; yield: 200 mg (81%).
1H NMR (500 MHz, CDCl3):  = 8.05 (d, J = 7.5 Hz, 2 H), 7.50 (d, J = 7.5
13C NMR (125 MHz, CDCl3):  = 166.53, 159.71, 133.00, 130.31,
130.13, 129.71, 128.39, 128.21, 114.02, 66.59, 55.28.
Hz, 2 H), 7.48–7.37 (m, 5 H), 5.41 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 165.57, 139.52, 135.88, 131.15,
4-Chlorobenzyl Benzoate (3p)26
128.77, 128.70, 128.64, 128.43, 128.31, 66.98.
Colorless oil; yield: 177 mg (72%).
1H NMR (500 MHz, CDCl3):  = 8.07–8.05 (m, 2 H), 7.58–7.53 (m, 1 H),
7.45–7.40 (m, 2 H), 7.40–7.33 (m, 4 H), 5.32 (s, 2 H).
Benzyl 4-Bromobenzoate (3g)23
Colorless oil; yield: 212 mg (73%).
1H NMR (500 MHz, CDCl3):  = 7.97 (d, J = 8.5 Hz, 2 H), 7.59 (d, J = 8.5
Hz, 2 H), 7.49 (d, J = 7.5 Hz, 2 H), 7.46–7.38 (m, 3 H), 5.41 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 166.16, 134.66, 134.02, 133.15,
129.92, 129.65, 129.56, 128.75, 128.74, 128.43, 65.78, 65.77.
13C NMR (125 MHz, CDCl3):  = 165.69, 135.85, 131.78, 131.29,
4-Bromobenzyl Benzoate (3q)24
129.09, 128.71, 128.44, 128.31, 128.23, 67.01.
Colorless oil; yield: 212 mg (73%).
1H NMR (500 MHz, CDCl3):  = 8.10 (dd, J = 8.1, 0.9 Hz, 2 H), 7.55 (t, J =
7.4 Hz, 1 H), 7.50 (d, J = 8.3 Hz, 2 H), 7.43 (t, J = 7.8 Hz, 2 H), 7.32 (d, J =
8.3 Hz, 2 H), 5.31 (s, 2 H).
Benzyl 2-Methylbenzoate (3h)24
Colorless oil; yield: 122 mg (54%).
1H NMR (500 MHz, CDCl3):  = 8.05 (d, J = 8.0 Hz, 1 H), 7.52 (d, J = 7.5
Hz, 2 H), 7.45 (dd, J = 7.0, 2.0 Hz, 3 H), 7.40 (t, J = 7.0 Hz, 1 H), 7.29 (t,
J = 7.0 Hz, 2 H), 5.42 (s, 2 H), 2.70 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 166.21, 135.19, 133.22, 131.77,
129.95, 129.90, 129.74, 128.50, 122.30, 65.88.
13C NMR (125 MHz, CDCl3):  = 167.37, 140.44, 136.25, 132.14,
2-Methylbenzyl Benzoate (3r)24
131.79, 130.78, 129.53, 128.67, 128.28, 128.26, 125.80, 66.56, 21.91.
Colorless oil; yield: 163 mg (72%).
1H NMR (500 MHz, CDCl3):  = 8.19–8.13 (m, 2 H), 7.59 (t, J = 7.4 Hz, 1
H), 7.49 (dt, J = 15.7, 7.6 Hz, 3 H), 7.36–7.26 (m, 3 H), 5.45 (s, 2 H), 2.48
(s, 3 H).
Benzyl 2-Methoxybenzoate (3i)12a
Colorless oil; yield: 140 mg (58%).
1H NMR (500 MHz, CDCl3):  = 7.88 (dd, J = 8.0, 1.0 Hz, 1 H), 7.50–7.46
(m, 3 H), 7.41 (t, J = 7.5 Hz, 2 H), 7.36 (t, J = 7.0 Hz, 1 H), 6.99 (t, J = 7.5
Hz, 2 H), 5.39 (s, 2 H), 3.90 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 166.41, 137.10, 134.10, 133.10,
130.50, 130.24, 129.75, 129.34, 128.65, 128.48, 126.15, 65.27, 19.07.
13C NMR (125 MHz, CDCl3):  = 165.93, 159.40, 136.32, 133.72,
2-Chlorobenzyl Benzoate (3s)24
131.79, 128.57, 128.11, 120.15, 119.93, 112.11, 66.50, 55.95.
Colorless oil; yield: 160 mg (65%).
1H NMR (500 MHz, CDCl3):  = 8.14 (dd, J = 8.2, 1.0 Hz, 2 H), 7.60–7.51
(m, 2 H), 7.50–7.39 (m, 3 H), 7.29 (dt, J = 5.7, 2.1 Hz, 2 H), 5.50 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 166.19, 133.81, 133.73, 133.19,
Benzyl 2-Chlorobenzoate (3j)12a
Colorless oil; yield: 148 mg (60%).
1H NMR (500 MHz, CDCl3):  = 7.90 (dd, J = 7.5, 1.5 Hz, 1 H), 7.51 (d, J =
7.5 Hz, 2 H), 7.49–7.37 (m, 5 H), 7.31 (t, J = 7.5 Hz, 1 H), 5.43 (s, 2 H).
129.98, 129.83, 129.79, 129.64, 129.58, 128.48, 126.99, 64.07.
13C NMR (125 MHz, CDCl3):  = 165.47, 135.66, 133.89, 132.72,
2-Bromobenzyl Benzoate (3t)24
131.59, 131.16, 130.00, 128.69, 128.44, 128.43, 126.66, 67.32.
Colorless oil; yield: 175 mg (60%).
1H NMR (500 MHz, CDCl3):  = 8.17–8.15 (m, 2 H), 7.61 (dd, J = 8.0, 0.8
Hz, 1 H), 7.60–7.55 (m, 1 H), 7.53 (d, J = 7.5 Hz, 1 H), 7.46 (t, J = 7.7 Hz,
2 H), 7.34 (td, J = 7.6, 0.9 Hz, 1 H), 7.20 (td, J = 7.9, 1.5 Hz, 1 H), 5.48 (s,
2 H).
13C NMR (125 MHz, CDCl3):  = 166.12, 135.48, 133.22, 132.94,
129.98, 129.90, 129.83, 129.81, 128.51, 127.62, 123.52, 66.24.
4-Methylbenzyl Benzoate (3m)24
Colorless oil; yield: 151 mg (67%).
1H NMR (500 MHz, CDCl3):  = 8.17 (d, J = 7.5 Hz, 2 H), 7.58 (t, J = 7.5
Hz, 1 H), 7.47 (t, J = 7.5 Hz, 2 H), 7.43 (d, J = 7.5 Hz, 2 H), 7.26 (d, J = 7.5
Hz, 2 H), 5.41 (s, 2 H), 2.43 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 166.47, 138.09, 133.21, 133.05,
130.35, 129.78, 129.37, 128.47, 128.44, 66.73, 21.28.
3-Methylbenzyl Benzoate (3u)27
Colorless oil; yield: 150 mg (77%).
4-(tert-Butyl)benzyl Benzoate (3n)25
1H NMR (500 MHz, CDCl3):  = 8.12–8.05 (m, 2 H), 7.57–7.47 (m, 1 H),
7.45–7.35 (m, 2 H), 7.33–7.22 (m, 3 H), 7.13 (d, J = 6.3 Hz, 1 H), 5.32 (s,
2 H), 2.35 (s, 3 H).
Colorless oil; yield: 163 mg (61%).
1H NMR (500 MHz, CDCl3):  = 8.11 (d, J = 7.5 Hz, 2 H), 7.57 (t, J = 7.5
Hz, 1 H), 7.46–7.42 (m, 6 H), 5.37 (s, 2 H), 1.36 (s, 9 H).
13C NMR (125 MHz, CDCl3):  = 166.35, 138.21, 136.01, 133.02,
13C NMR (125 MHz, CDCl3):  = 166.54, 151.33, 133.11, 133.01,
130.19, 129.68, 129.01, 128.92, 128.52, 128.39, 125.28, 66.70, 21.36.
130.28, 129.76, 128.39, 128.16, 125.57, 66.61, 34.65, 31.37.
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H

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3-Chlorobenzyl Benzoate (3v)27
4-(tert-Butyl)benzyl Acetate (4n)30
Colorless oil; yield: 174 mg (83%).
Colorless oil; yield: 117 mg (57%).
1H NMR (500 MHz, CDCl3):  = 8.12 (dd, J = 8.1, 0.8 Hz, 2 H), 7.61–7.53
(m, 1 H), 7.50–7.41 (m, 3 H), 7.33 (ddt, J = 12.3, 8.4, 4.3 Hz, 3 H), 5.34
(s, 2 H).
1H NMR (500 MHz, CDCl3):  = 7.48 (d, J = 8.2 Hz, 2 H), 7.39 (d, J = 8.1
Hz, 2 H), 5.17 (s, 2 H), 2.14 (s, 3 H), 1.42 (s, 9 H).
13C NMR (125 MHz, CDCl3):  = 170.77, 151.24, 133.12, 128.33,
125.53, 66.17, 34.62, 31.40, 20.98.
13C NMR (125 MHz, CDCl3):  = 166.18, 138.20, 134.49, 133.23,
129.96, 129.91, 129.76, 128.49, 128.40, 128.15, 126.19, 65.75.
4-Methoxybenzyl Acetate (4o)30
3-Bromobenzyl Benzoate (3w)25
Colorless oil; yield: 108 mg (60%).
Colorless oil; yield: 227 mg (78%).
1H NMR (500 MHz, CDCl3):  = 7.28 (d, J = 7.9 Hz, 2 H), 7.23 (d, J = 7.8
Hz, 2 H), 5.13 (s, 2 H), 2.41 (s, 3 H), 2.13 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.87, 159.65, 130.12, 128.10,
113.91, 66.05, 55.15, 20.94.
1H NMR (500 MHz, CDCl3):  = 8.19–8.07 (m, 2 H), 7.64 (s, 1 H), 7.62–
7.56 (m, 1 H), 7.48 (dd, J = 15.6, 7.7 Hz, 3 H), 7.40 (d, J = 7.6 Hz, 1 H),
7.28 (t, J = 7.8 Hz, 1 H), 5.35 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 166.25, 138.38, 133.26, 131.37,
4-Chlorobenzyl Acetate (4p)29
131.09, 130.24, 129.86, 129.78, 128.50, 126.70, 122.68, 65.73.
Colorless oil; yield: 138 mg (75%).
1H NMR (500 MHz, CDCl3):  = 7.28 (q, J = 8.5 Hz, 4 H), 5.04 (s, 2 H),
2.07 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.68, 134.52, 129.61, 128.69,
128.17, 65.38, 20.85.
Naphthalen-2-ylmethyl Benzoate (3x)24
Colorless oil; yield: 183 mg (70%).
1H NMR (500 MHz, CDCl3):  = 8.20 (d, J = 7.9 Hz, 2 H), 7.97 (s, 1 H),
7.96–7.88 (m, 3 H), 7.62 (t, J = 8.5 Hz, 2 H), 7.56 (pent, J = 4.6 Hz, 2 H),
7.50 (t, J = 7.7 Hz, 2 H), 5.60 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 166.54, 133.56, 133.31, 133.23,
133.15, 130.23, 129.82, 128.52, 128.49, 128.10, 127.82, 127.42,
126.41, 126.37, 125.97, 66.94.
4-Bromobenzyl Acetate (4q)31
Colorless oil; yield: 170 mg (74%).
1H NMR (500 MHz, CDCl3):  = 7.46 (d, J = 8.3 Hz, 2 H), 7.21 (d, J = 8.2
Hz, 2 H), 5.03 (s, 2 H), 2.08 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.69, 135.00, 131.68, 129.91,
122.23, 65.44, 20.93.
Benzyl Acetate (4a)13a
Colorless oil.
1H NMR (500 MHz, CDCl3):  = 7.39 (dd, J = 9.3, 3.6 Hz, 4 H), 7.35 (ddd,
J = 8.8, 7.1, 4.2 Hz, 1 H), 5.15 (s, 2 H), 2.11 (d, J = 1.4 Hz, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.75, 136.08, 128.59, 128.29,
2-Methylbenzyl Acetate (4r)13a
Colorless oil; yield: 115 mg (70%).
128.25, 66.26, 20.93.
1H NMR (500 MHz, CDCl3):  = 7.37 (d, J = 7.2 Hz, 1 H), 7.31–7.26 (m, 1
H), 7.23 (dd, J = 10.3, 7.4 Hz, 2 H), 5.16 (s, 2 H), 2.39 (s, 3 H), 2.10 (d, J =
1.2 Hz, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.62, 136.90, 134.09, 130.37,
129.26, 128.52, 126.06, 64.59, 20.71, 18.78.
Benzyl 2-(3-Methoxyphenyl)acetate (4b)28
Colorless oil; yield: 133 mg (52%).
1H NMR (500 MHz, CDCl3):  = 7.48–7.37 (m, 5 H), 7.33 (t, J = 7.9 Hz, 1
H), 6.97 (dd, J = 8.0, 4.9 Hz, 2 H), 6.92 (dd, J = 8.2, 2.5 Hz, 1 H), 5.24 (s,
2 H), 3.84 (s, 3 H), 3.74 (s, 2 H).
13C NMR (125 MHz, CDCl3):  = 170.11, 158.64, 134.80, 134.24,
128.44, 127.42, 127.10, 127.05, 120.54, 113.73, 116.69, 65.46, 53.96,
40.21.
2-Chlorobenzyl Acetate (4s)29
Colorless oil; yield: 121 mg (66%).
1H NMR (500 MHz, CDCl3):  = 7.41–7.36 (m, 1 H), 7.36–7.32 (m, 1 H),
7.25–7.20 (m, 2 H), 5.19 (s, 2 H), 2.09 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.51, 135.64, 133.57, 129.79,
129.50, 129.47, 126.88, 63.52, 20.73.
Benzyl Propionate (4c)26
Colorless oil; yield: 111 mg (68%).
1H NMR (500 MHz, CDCl3):  = 7.38–7.316 (m, 5 H), 5.14 (s, 2 H), 2.40
(d, J = 7.5 Hz, 2 H), 1.83 (t, J = 7.5 Hz, 3 H).
13C NMR (125 MHz, CDCl3):  = 174.27, 136.19, 128.57, 128.19, 66.14,
2-Bromobenzyl Acetate (4t)29
Colorless oil; yield: 149 mg (65%).
1H NMR (500 MHz, CDCl3):  = 7.57 (dd, J = 8.0, 1.1 Hz, 1 H), 7.40 (dd,
J = 7.6, 1.6 Hz, 1 H), 7.31 (td, J = 7.5, 1.2 Hz, 1 H), 7.19 (td, J = 7.8, 1.7
Hz, 1 H), 5.19 (s, 2 H), 2.14 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.57, 135.25, 132.82, 129.84,
129.72, 127.52, 123.40, 65.79, 20.85.
27.61, 9.13.
4-Methylbenzyl Acetate (4m)29
Colorless oil; yield: 105 mg (62%).
1H NMR (500 MHz, CDCl3):  = 7.32 (d, J = 7.9 Hz, 4 H), 7.23 (d, J = 7.8
Hz, 4 H), 5.13 (s, 4 H), 2.41 (s, 7 H), 2.13 (s, 6 H).
13C NMR (125 MHz, CDCl3):  = 170.88, 138.05, 133.08, 129.28,
128.51, 66.26, 21.20, 20.98.
3-Methylbenzyl Acetate (4u)13a
Colorless oil; yield: 131 mg (80%).
1H NMR (500 MHz, CDCl3):  = 7.31 (t, J = 7.5 Hz, 1 H), 7.25–7.17 (m, 3
H), 5.13 (s, 2 H), 2.42 (s, 3 H), 2.14 (s, 3 H).
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H

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13C NMR (125 MHz, CDCl3):  = 170.86, 138.24, 135.95, 129.06,
129.04, 128.53, 125.42, 66.37, 21.35, 20.98.
(4) (a) Butta, N. A.; Zhang, W. Chem. Soc. Rev. 2015, 44, 7929; and
references cited therein. (b) Fu, J.; Huo, X.; Li, B.; Zhang, W. Org.
Biomol. Chem. 2017, 15, 9747; and references cited therein.
(c) Cheng, Q.; Tu, H.-F.; Zheng, C.; Qu, J.-P.; Helmchen, G.; You,
S.-L. Chem. Rev. 2019, 119, 1855; and references cited therein.
(5) For selected examples, see: (a) Huo, X.; Quan, M.; Yang, G.;
Zhao, X.; Liu, D.; Liu, Y.; Zhang, W. Org. Lett. 2014, 16, 1570.
(b) Yao, K.; Yuan, Q.; Qu, X.; Liu, Y.; Liu, D.; Zhang, W. Chem. Sci.
2019, 10, 1767. (c) Zhang, J.; Huo, X.; Li, B.; Chen, Z.; Zou, Y.;
Sun, Z.; Zhang, W. Adv. Synth. Catal. 2019, 361, 1130.
3-Chlorobenzyl Acetate (4v)29
Colorless oil; yield: 155 mg (84%).
1H NMR (500 MHz, CDCl3):  = 8.14–8.10 (m, 3 H), 7.34 (s, 1 H), 7.29–
7.25 (m, 2 H), 7.24–7.19 (m, 1 H), 5.05 (s, 2 H), 2.09 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 170.63, 138.02, 134.37, 129.84,
128.29, 128.10, 126.15, 65.28, 20.83.
(6) For selected examples, see: (a) Xie, P.; Wang, J.; Fan, J.; Liu, Y.;
Wo, X.; Loh, T.-P. Green Chem. 2017, 19, 2135. (b) Dai, X.; Cheng,
D.; Guan, B.; Mao, W.; Xu, X.; Li, X. J. Org. Chem. 2014, 79, 7212.
(c) Trost, B. M.; Nagaraju, A.; Wang, F.; Zuo, Z.; Xu, J.; Hull, K. L.
Org. Lett. 2019, 21, 1784. (d) Ueda, M.; Hartwig, J. F. Org. Lett.
2010, 12, 92. (e) Leitner, A.; Shu, C.; Hartwig, J. F. Org. Lett. 2005,
7, 1093.
(7) For selected examples, see: (a) Das, B.; Banerjee, J.; Chowdhury,
N.; Majhi, A. Chem. Pharm. Bull. 2006, 54, 1725. (b) Das, B.;
Chowdhury, N.; Banerjee, J.; Majhi, A. Tetrahedron Lett. 2006,
47, 6615. (c) Linstadt, R. T. H.; Peterson, C. A.; Jette, C. I.;
Boskovic, Z. V.; Lipshutz, B. H. Org. Lett. 2017, 19, 328.
(8) For selected examples, see: (a) Santos, M. S.; Coelho, F. RSC Adv.
2012, 2, 3237. (b) Lawrence, N. J.; Crump, J. P.; McGown, A. T.;
Hadfield, J. A. Tetrahedron Lett. 2001, 42, 3939. (c) Bikshapathi,
R.; Prathima, P. S.; Rao, V. J. New J. Chem. 2016, 40, 10300.
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1834.
3-Bromobenzyl Acetate (4w)32
Colorless oil; yield: 183 mg (80%).
1H NMR (500 MHz, CDCl3):  = 7.48 (s, 1 H), 7.41 (d, J = 7.9 Hz, 1 H),
7.24 (d, J = 7.7 Hz, 1 H), 7.18 (t, J = 7.8 Hz, 1 H), 5.03 (s, 2 H), 2.07 (s, 3
H).
13C NMR (125 MHz, CDCl3):  = 170.61, 138.27, 131.23, 131.02,
130.13, 126.65, 122.54, 65.22, 20.88.
Naphthalen-2-ylmethyl Acetate (4x)29
Colorless oil; yield: 136 mg (68%).
1H NMR (500 MHz, CDCl3):  = 7.92–7.82 (m, 4 H), 7.58–7.48 (m, 3 H),
5.32 (s, 2 H), 2.18 (s, 3 H).
13C NMR (125 MHz, CDCl3):  = 171.01, 133.38, 133.24, 133.16,
128.43, 128.02, 127.76, 127.42, 126.36, 126.32, 125.95, 66.50, 21.09.
(10) Vellakkaran, M.; Andappan, M. M. S.; Kommu, N. Green Chem.
2014, 16, 2788.
Funding Information
(11) (a) Dong, Y.-X.; Li, Y.; Gu, C.-C.; Jiang, S.-S.; Song, R.-J.; Li, J-H.
Org. Lett. 2018, 20, 7594. (b) Yin, Z.; Sun, P. J. Org. Chem. 2012,
77, 11339. (c) Adib, M.; Pashazadeh, R.; Rajai-Daryasarei, S.;
Moradkhani, F.; Jahani, M.; Gohari, S. J. A. Tetrahedron 2018, 74,
3858.
The authors gratefully acknowledge financial support from National
Key Research and Development Program of China (2017YFB0102900)
and State Key Laboratory of Applied Organic Chemistry, Lanzhou Uni-
versity. This work is also sponsored by Natural Science Foundation of
(12) For selected examples, see: (a) Liu, H.; Shi, G.; Pan, S.; Jiang, Y.;
Zhang, Y. Org. Lett. 2013, 15, 4098. (b) Im, H.; Kang, D.; Choi, S.;
Shin, S.; Hong, S. Org. Lett. 2018, 20, 7437. (c) Leth, L. A.;
Næsborg, L.; Reyes-Rodríguez, G. J.; Tobiesen, H. N.; Iversen, M.
V.; Jørgensen, K. A. J. Am. Chem. Soc. 2018, 140, 12687. (d) Hu, L.;
Yuan, J.; Fu, J.; Zhang, T.; Gao, L.; Xiao, Y.; Mao, P.; Qu, L. Eur. J.
Org. Chem. 2018, 4113. (e) Liu, H.; Ma, L.; Zhou, R.; Chen, X.;
Fang, W.; Wu, J. ACS Catal. 2018, 8, 6224. (f) Jiang, H.; Sha, S.-C.;
Jeong, S. A.; Manor, B. C.; Walsh, P. J. Org. Lett. 2019, 21, 1735.
(g) Rout, S. K.; Guin, S.; Ghara, K. K.; Banerjee, A.; Patel, B. K. Org.
Lett. 2012, 14, 3982. (h) Yin, Z.; Sun, P. J. Org. Chem. 2012, 77,
11339.
(13) (a) Guo, L.-N.; Wang, S.; Duan, X.-H.; Zhou, S.-L. Chem. Commun.
2015, 51, 4803. (b) Zhou, S.-L.; Guo, L.-N.; Wang, H.; Duan, X.-H.
Chem. Eur. J. 2013, 19, 12970. (c) Zhou, S.-L.; Guo, L.-N.; Wang,
S.; Duan, X.-H. Chem. Commun. 2014, 50, 3589.
(14) (a) Liu, Z.; Zhang, X.; Li, X.; Li, F.; Li, C.; Jia, X.; Li, J. Org. Lett.
2016, 18, 4052. (b) Li, C.; Jin, T.; Zhang, X.; Li, C.; Jia, X.; Li, J. Org.
Lett. 2016, 18, 1916. (c) Li, C.; Deng, H.; Li, C.; Jia, X.; Li, J. Org.
Lett. 2015, 17, 5718. (d) Li, C.; Deng, H.; Jin, T.; Liu, Z.; Jiang, R.;
Li, C.; Jia, X.; Li, J. Synthesis 2017, 49, 4350.
Shanghai (18ZR1413900) and Shanghai Pujiang Program (17PJD016).
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Supporting information for this article is available online at
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References
(1) Otera, J. Esterification Methods, Reactions and Applications;
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© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–H