Liquid-Assisted Grinding Accelerating: Suzuki-Miyaura Reaction of Aryl Chlorides under High-Speed Ball-Milling Conditions

Article abstract of DOI:10.1021/acs.joc.6b01938

The effect of liquid-assisted grinding has been studied using mechanical Suzuki-Miyaura reaction of aryl chlorides as the model reaction. Catalytic systems of Davephos and PCy₃ are tested respectively showing strong influences from different liquids. Unexpected improvement of yield over 55% is observed using alcohols as additives, which is explained by in situ formed alkoxides and their participation in oxidative addition. Further expansion of substrates using Pd(OAc)₂/PCy₃/MeOH system gives desired products in good to high yields.

Full text of DOI:10.1021/acs.joc.6b01938

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Note
Liquid-Assisted Grinding Accelerating: Suzuki-Miyaura Reaction
of Aryl Chlorides under High-Speed Ball-Milling Conditions
Zhi-Jiang Jiang, Zhen-Hua Li, Jing-Bo Yu, and Wei-Ke Su
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b01938 • Publication Date (Web): 01 Oct 2016
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The Journal of Organic Chemistry
Liquid-Assisted Grinding Accelerating: Suzuki-Miyaura Reaction of Aryl Chlorides under High-Speed Ball-
Milling Conditions
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Zhi-Jiang Jiang,a Zhen-Hua Li,*,b Jing-Bo Yu,a Wei-Ke Su*,a
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a National Engineering Research Center for Process Development of Active Pharmaceutical Ingredients, Collaborative
Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hang-
zhou 310014, P. R. China
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b Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of
Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, P. R. China
The effect of liquid-assisted grinding has been studied using mechanical Suzuki-Miyaura reaction of aryl
chlorides as the model reaction. Catalytic systems of Davephos and PCy3 are tested respectively showing strong influ-
ences from different liquids. Unexpected improvement of yield over 55% is observed using alcohols as additives,
which is explained by in-situ formed alkoxides and their participation in oxidative addition. Further expansion of sub-
strates using Pd(OAc)2/PCy3/MeOH system gives desired products in good to high yields.
High-speed ball-milling (HSBM) promoted mechanical organic reaction has been extensively studied during the
past decades, showing its unusual features of high efficiency, excellent chemo-selectivity, and sometimes unique reac-
tivity.1 Although previous research of this field mainly emphasized on its advantage of totally solvent-free characteri-
zation during the reaction procedures from the aspect of green chemistry, introducing small amount of liquid during the
grinding, which is called liquid-assisted grinding (LAG),2 has attracted considerable attention from the community, and
shows its potential in chemo-selectivity control,3 and yield improvement.4 To unveil the relationship, Mack et. al
showed the diyne/enyne selectivity depended on solvents’ polarity,3b while Halasz and Užarević reported the correla-
tion of reaction rate with solvents’ donor number.4a However, the detailed mechanism of solvent molecule’s participa-
tion is still unclear for those cases.
During our continuous research interest toward fast organic synthesis under HSBM conditions5, the unusual fea-
tures of LAG have attracted our attention. As the small amount of liquid has a strong influence on reaction outcomes,
we envision LAG could also be used to facilitate the procedure of transition-metal catalyzed reactions by applying the
solvent molecules as ligands. Suzuki-Miyaura reaction as one of the most powerful tools for C-C bond construction has
been successfully studied under HSBM conditions using aryl bromides as substrates.6 Also, the reaction has even been
used as a model for mechanochemical parameter investigation,6d,e which prove better understand the ball-milling pro-
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cess. Despite the ligand-free and extremely fast manner of these reactions, the coupling of aryl chlorides remains a
challenge, where the only successful case was reported by Cravotto,7 using hexamethylene diisocyanate cross-linked
chitosan/Pd(II) to give moderate to high yields. Thus, this reaction is chosen as the model for the LAG examination to
further improve the utility. Herein, we wish to uncover our preliminary result of LAG promoted highly efficient me-
chanical Suzuki-Miyaura reaction of aryl chlorides.
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At the commencement, p-chloroacetophenone 1a and phenylboronic acid 2a were chosen as model substrates for
primary reaction optimization (eq. 1). Considering the inert nature of aryl chlorides, bidentate ligand Davephos was
firstly used to establish the model reaction.8 Although, the primary attempts gave low yield after 60 minutes’ grinding,
the following optimization of mechanochemical parameters improved the yield to 55% (see Table S1 in the Supporting
Information for more details). Several simpler ligands were then examined, including dppf, dppe, dppp, dppb, PCy3,9
and PPh3 (Table 1). Accordingly, PCy3 gave a better result, which has been involved in aryl chlorides activation previ-
ously.10 Bis-triphenylphospite bidentate ligands with inappropriate steric hindrance failed in cleaving C-Cl bond (Table
1, entries 3-6). A similar result was also found by using monodentate PPh3 as the ligand. Further optimization of reac-
tion system involving catalytic system loading and ratio based on PCy3 system led to an improvement in yield for both
Davephos and PCy3 system (see Table S2 in the Supporting Information). Then we turned our focus on the LAG effect
of this reaction by adding liquid to the system.
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Initially, we hypothesized that the solvents commonly used in Suzuki-Miyaura reaction may lead good result in
mechanochemistry environment.11 Thus, examination using THF, dioxane, DMF, and CH3CN as additives (η = 0.045
μL/mg)12 was performed under the optimal conditions (Table 2, entries 2-5). In the case of THF and dioxane, positive
effects were observed. However, erosion of yields was found in the combination of Davephos/DMF and PCy3/CH3CN,
respectively. The strong fluctuation of yields implicates the phenomenon of solvent-dependence may also present in
the solvent-less environment. Thus, further examination of LAG additives was performed to have a glance at the inner
pattern.
Table 1. Examination of Ligands.a
no.
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7
8
ligand (mol%)
-
time/min b %yield c
120
90
n.d.
55
Davephos (10)
dppf (10)
dppe (10)
dppp (10)
dppb (10)
PCy3 (20)
PPh3 (20)
120
120
120
120
120
120
9
n.d.
n.d.
n.d.
21
n.d.
a Reaction conditions unless specified otherwise: 1a (0.5 mmol), 2a (0.6 mmol), Pd(OAc)2 (5 mol%), Ligand (5 mol%
for bidentate ligand or 10 mol% for monodentate ligand), and K2CO3 (5.0 equiv.) were placed in a 25 mL stainless-
steel vessel with two stainless-steel balls (ø = 1.4 cm). Ball milling conditions: 60 min at 30 Hz. b 5 min pause followed
after every 30 min grinding. c Yield based on 1a, average of three runs.
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Firstly, aprotic solvents were tested considering the potential dechlorination of aryl chlorides by protic solvents as
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alcohols.13 Inert low-polarity alkanes as n-hexane and n-heptane gave moderate positive-effect for both ligands, and
similar results were also obtained in the cases of dichloromethane and chloroform (Table 2, entries 6-9). Liner ethers
didn’t show positive-effect as their cyclic analogues (Table 2, entries 10-12), while ethyl ether gave unexpected posi-
tive result when combined with PCy3. High-polarity solvent also led to unpredictable results (Table 2, entries 13-15).
Ethyl acetate gave the most effective result for Davephos in the aprotic solvent test, while only small promotion was
found in the PCy3 system. The reactions with acetone show retard with Davephos, while a moderate improvement for
PCy3. However, dual negative effect was found when using DMSO as additive, which may cause by undesired coordi-
nation to the metal center.14
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Frustrated by the results above, protic solvents as methanol, ethanol, and H2O were then tested (Table 2, entries
16-18). To our surprise, strong positive-effect was found in both Davephos and PCy3 systems using alcohols as assisted
liquid, which afforded product in nearly quantitative yields. For the latter, over 55% improvement of yields were found
using methanol and ethanol. H2O also elevated the yields to 88% and 87% for each system. Inspired by the results, al-
cohols with a different degree of steric hindrance were then screened (Table 2, entries 19-22). Linear alcohols as n-
PrOH and n-BuOH also gave high yields, but the results with branched alcohols depraved with the increase of steric
hindrance as expected. It’s noteworthy that the Davephos system seemed to be more sensitive to hindrance, where i-
PrOH and t-BuOH gave similar results. Prolonging the grinding time lead these reactions to moderate or good yields
implicating the steric hindrance has influenced on the reaction rate. Besides, ethylene glycol was also tested, which
gave moderate positive effect (Table 2, entry 23).
Table 2. Examination of LAG additives.a
Davephos
PCy3
no. Solv.
%yield b %dev. c %yield b %dev. c
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3
4
5
6
7
8
9
neat
THF
dioxane
DMF
CH3CN
n-hexane 83
n-heptane 80
CH2Cl2
CHCl3
66
87
90
85
60
-
38
56
47
37
48
55
59
59
54
67
42
37
47
52
31
97
94
87
95
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+ 19
+ 23
+ 18
- 6
+ 17
+ 14
+ 13
+ 2
- 6
- 10
- 4
+ 28
- 19
- 15
+ 32
+ 33
+ 21
+ 23
+ 18
+ 9
- 4
+ 10
+ 17
+ 21
+ 21
+ 17
+ 29
+ 4
- 1
+ 9
+ 14
- 7
+ 59
+ 56
+ 49
+ 57
79
68
60
10 Et2O
11 (CH2OMe)2 56
12 PEG-600 62
13 EtOAc
14 acetone
15 DMSO
16 MeOH
17 EtOH
18 H2O
94
47
51
98
99
88
89
19 n-PrOH
20 i-PrOH
68 (92)d + 2
+ 14
67 (87)d + 1
23 (CH2OH)2 72 + 6
77 (90)d + 39
91 + 53
42 (71)d + 4
65 + 27
21 n-BuOH 90
22 t-BuOH
a
Reaction conditions unless specified otherwise: 1a (0.5 mmol), 2a (0.6 mmol), Pd(OAc)2 (0.05 equiv.), Davephos
(0.05 equiv.) or PCy3∙HBF4 (0.1 equiv.), K2CO3 (5.0 equiv.) and LAG additive (η = 0.045 μL/mg) were placed in a 25
mL stainless-steel vessel with two stainless-steel balls (ø = 1.4 cm). Ball milling conditions: 60 min at 30 Hz. b Yield
based on 1a, average of three runs. c Deviation of yield from neat conditions. d 120 min at 30 Hz.
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Further attempts were paid to explain the unexpected role of alcohols in Pd(OAc)2/PCy3 system. Based on the re-
sult of base screening (Scheme 1a), carbonates gave better result than common used CsF and KF. Thus, we envision
the alcohols may react with carbonates and transform to alkoxides by releasing CO2 during the grinding process
(Scheme 1b). Further results by replacing the alcohol/base combination by potassium or sodium methoxide as base
provided support for the hypothesis, which gave relative yields of 95% and 88% respectively. From the aspect of the
classic mechanism of Suzuki-Miyaura reaction (Scheme 1c),15 alkoxides usually participate in the steps of ligand ex-
change and boronic acid activation. While in this mechanical Suzuki-Miyaura reaction presented, it’s clear that the ste-
ric hindrance of alcohols has a strong influence on the reaction rate (Table 2, entries 20,22), which is mainly controlled
by the rate of oxidative addition of C-Cl bond (I to II) as the rate determining step. Thus, based on previous mecha-
nism study,11 we proposed that a fast synergic oxidative addition is occurred under HSBM condition though TS, which
gave intermediate III from I directly.
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Scheme 1. Mechanism studies
Finally, after a simple test to reduce of the amount of catalyst loading,16 the substrates scope was then examined
using 2 mol% of Pd(OAc)2/PCy3 with methanol (η = 0.045 μL/mg), which was summarized in Table 3. Firstly, several
aryl boronic acids were tested, showing both electron-rich and -deficient species 2a-i worked well during the 99 min’s
grinding. A slight drop in yields was observed using steric 2f and strong electron withdrawing 2h as coupling partner,
where both reactions gave acceptable yields of 87% and 88%, respectively. Next, several activated aryl chlorides were
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explored, and all the substrates 1b-f tested gave yields over 90%. Unsubstituted chlorobenzene 1g also afforded high
yield in this sealed environment, without significant losing by volatilization. Afterward, unactivated aryl chlorides
bearing electron-donating substitutions were also examined. Accordingly, acetylamino group at para-position gave
moderate yield, while the directing effect of this group helped the ortho-substituted analogue to afford higher yield. To
our surprise, unprotected p-chloroaniline gave C-C bond coupling product 3lc sorely, where no trace of C-N bond for-
mation was detected. Besides, the reaction protocol could also be used in the synthesis of Fenbufen ethyl ester 3na
with a high yield of 91%. Scaling up of model reaction to gram level still gave good yield of 95%, which was obtained
using 0.5 mol% catalytic system with 2.5 equiv. of K2CO3.17 Finally, the protocol was compared with the solvent-based
reaction using methanol, dioxane, and dioxane (5% methanol) as solvent. Surprisingly, no conversion of acetophenone
was detected after 6 hours stirring under room temperature. Further elevating of reaction temperature for the reaction
of dioxane and dioxane (5% methanol) gave 61% and 63% after 6 hours’ refluxing, while the methanol solvated reac-
tion only gave less than 10% product under similar conditions.
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Table 3. Examination of substrate scope. a
a
Reaction conditions unless specified otherwise: 1a (1.0 mmol), 2a (1.2 mmol), Pd(OAc)2 (2 mol%), PCy3∙HBF4 (4
mol%), K2CO3 (5.0 equiv.) and MeOH (η = 0.045 μL/mg) were placed in a 25 mL stainless-steel vessel with two stain-
less-steel balls (ø = 1.4 cm). Ball milling conditions: 99 min at 30 Hz. Yield based on 1, average of two runs. b 1a (10.0
mmol), 2a (12.0 mmol), Pd(OAc)2 (0.5 mol%), PCy3∙HBF4 (1.0 mol%), K2CO3 (2.5 equiv.) and MeOH (η = 0.045
μL/mg) were placed in a 50 mL stainless-steel vessel with two stainless-steel balls (ø = 1.4 cm). Ball milling conditions:
120 min at 30 Hz.
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In summary, we have disclosed a study about LAG accelerated high-efficiency aryl chlorides participated Suzuki-
Miyaura reaction under HSBM condition. The result implicates the LAG effect doesn’t only because providing sub-
stoichiometric solvent-environment, but may also participate in the formation of mechanically induced transition spe-
cies. Thus, this technique may have the potential to induce higher catalytic activity for existing systems under HSBM
conditions. Expansion of substrate scope showed the system build in this work could be applied to both activated and
unactivated aryl chlorides with good to high yields.
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EXPERIMENTAL SECTION
General Information. All reagents were obtained from commercial suppliers and used without further purifica-
tion, unless otherwise indicated. The mechanochemical reactions were performed using a commercial Mix-Miller with
maximum grinding frequency of 30 Hz. TLC (Thin-Layer Chromatography) analysis was performed using pre-coated
glass plates. Melting points (m.p.) were obtained on a digital melting point apparatus and uncorrected. NMR spectra
were recorded with 400 MHz and 500 MHz spectrometer for H and 126 MHz for 13C, TMS was used as internal
1
standard. Mass spectra were measured with a HRMS-ESI-Q-TOF and a low resolution MS instrument using ESI ioni-
zation. The optimization experiments were tracked with TLC every 30 min grinding, while substrate scope examination
were grinding without interruption.
General procedure for the synthesis of biaryls. A mixture of substrate 1 (1.0 mmol), 2 (1.2 mmol), Pd(OAc)2 (2
mol%), PCy3∙HBF4 (4 mol%), K2CO3 (5.0 equiv.) and MeOH (ƞ = 0.045 µL/mg) were added to the 25 mL screw-
capped stainless steel vessel, along with two stainless steel balls (ø = 1.4 cm). After that, the vessel was placed in the
mixer mill, and the contents were ball milled at 30 Hz for 99 min. At the end of the reaction, small portion (3 mL) ethyl
acetate were added in to the vessel and grinding for another 2 min at 30 Hz, which was filtered and washed with HCl
(1M). Then, after the washing by brine, the organic layer was dried over anhydrous sodium sulfate and concentrated in
vacuo to give a residue, which was purified by flash column chromatography on silica gel (eluents: n-hexane/ethyl ace-
tate = 10:1) to give the desired product.
General procedure for comparison experiment in solvent environment. In an oven-dried 10 mL Schlenk tube,
phenylboronic acid (1.2 mmol), Pd(OAc)2 (2 mol%), PCy3∙HBF4 (4 mol%), K2CO3 (5.0 equiv.) were weighted. The
tube was then sealed, evacuated and re-filled with Ar for three times. Then solvent (5 mL) and acetophenone (1.0 mmol)
were added. The mixture was then stirred at specified temperature or r.t. for 3 hrs. At the end of the reaction, the mix-
ture was filtered and washed with HCl (1M). Then, after the washing by brine, the organic layer was dried over anhy-
drous sodium sulfate and concentrated in vacuo to give a residue, which was purified by flash column chromatography
on silica gel (eluents: n-hexane/ethyl acetate = 10:1) to give the desired product.
1-([1,1'-Biphenyl]-4-yl)ethan-1-one (3aa)18 White solid (190.3 mg, 97% yield); m.p. 120.2-121.1 °C (lit.18 119-
1
120 °C); H NMR (400 MHz, Chloroform-d) δ 8.02 (d, J = 8.0 Hz, 2H), 7.67 (d, J = 8.4 Hz, 2H), 7.64-7.59 (m, 2H),
7.46 (t, J = 7.2 Hz, 2H), 7.39 (t, J = 7.2 Hz, 1H), 2.64 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.7, 145.7,
139.9, 135.9, 128.9, 128.9, 128.2, 127.2, 127.2, 26.6; MS (ESI): C14H12O ([M+H]+): calcd. 197.1, Found: 197.2.
1-(4'-Methyl-[1,1'-biphenyl]-4-yl)ethan-1-one (3ab).19 White crystal (201.7 mg, 96% yield); m.p. 118.9-120.6 °C
(lit.19 119-120 °C); 1H NMR (400 MHz, Chloroform-d) δ 8.01 (d, J = 7.6 Hz, 2H), 7.67 (d, J = 7.6 Hz, 2H), 7.53 (d, J =
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7.6 Hz, 2H), 7.28 (d, J = 7.6 Hz, 2 H), 2.65 (s, 3H), 2.42 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.7,
145.7, 138.2, 137.0, 135.6, 129.7, 128.9, 127.1, 126.9, 26.6, 21.1; MS (ESI): C15H15O ([M+H]+): calcd. 211.1, Found:
211.1.
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3
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5
6
7
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1-(4'-Methoxy-[1,1'-biphenyl]-4-yl)ethan-1-one (3ac).18 White crystal (208.4 mg, 92% yield),154.6-156.4°C (lit.18
155-156 °C); 1H NMR (500 MHz, Chloroform-d) δ 8.02 (dt, J = 8.5, 2.0 Hz, 2H), 7.66 (dt, J = 8.5, 2.0 Hz, 2H), 7.59
13
(dt, J = 8.5, 2.0 Hz, 2H), 7.02 (dt, J = 8.5, 2.0 Hz, 2H), 3.88 (s, 3H), 2.65 (s, 3H); C{H} NMR (126 MHz, Chloro-
9
form-d) δ 197.6, 159.9, 145.3, 135.3, 132.2, 128.9, 128.3, 126.6, 114.4, 55.3, 26.6; MS (ESI):C15H15O2 ([M+H]+):
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calcd. 226.1, Found: 227.1.
1-(4'-Fluoro-[1,1'-biphenyl]-4-yl)ethan-1-one (3ad).20 White crystal (203.1 mg, 95% yield); m.p. 102.5-104.0 °C
(lit.20 108.7-110.4 °C); 1H NMR (400 MHz, Chloroform-d) δ 8.01 (d, J = 7.2 Hz, 2H), 7.62 (d, J = 7.2 Hz, 2H), 7.60-
7.54 (m, 2H), 7.15 (m, 2H), 2.64 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.6, 163.0 (d, J = 249.5 Hz),
144.7, 136.0 (d, J = 3.3 Hz), 135.9, 129.0, 128.9, 127.1, 115.9 (d, J = 21.5 Hz), 26.6; MS (ESI): C14H12FO ([M+H]+):
calcd.215.1, Found: 215.1.
1-(4’-(Trifluoromethyl)-[1,1’-biphenyl]-4-yl)ethan-1-one (3ae).21 White crystal (254.1 mg, 95% yield); m.p.
122.2-122.9 (lit.21 120.6-121.4 °C); 1H NMR (500 MHz, Chloroform-d) δ 8.08 (dt, J = 9.0, 1.5 Hz, 2H), 7.75 (s, 4H),
7.71 (d, J = 8.5, 1.5 Hz, 2H), 2.67 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.5, 144.2, 143.4, 136.6, 130.2
(q, J = 32.4 Hz), 129.0, 127.6, 127.5, 125.9 (q, J = 3.8 Hz), 124.1 (q, J = 272.5 Hz), 26.7; MS (ESI): C15H12F3O
([M+H]+): calcd. 265.1, Found: 265.1.
1-(2'-Methyl-[1,1'-biphenyl]-4-yl)ethan-1-one (3af).19 Colourless oil (183.2 mg, 87% yield); H NMR (400 MHz,
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Chloroform-d) δ 8.00 (d, J = 8.0 Hz, 2H), 7.41 (d, J = 6.0 Hz, 2H), 7.31-7.15 (m, 4H), 2.64 (s, 3H), 2.27 (s, 3H); 13C{H}
NMR (126 MHz, Chloroform-d) δ 197.8, 147.0, 140.8, 135.6, 135.2, 130.5, 129.5, 129.5, 128.2, 127.9, 125.9, 26.6,
20.4; MS (ESI): C15H15O ([M+H]+): calcd. 211.1, Found: 211.1.
Methyl 4'-acetyl-[1,1'-biphenyl]-4-carboxylate (3ag).22 White solid (243.9 mg, 96% yield); m.p. 164.8-165.7 (lit.22
164.5-166.0 °C);1H NMR (500 MHz, Chloroform-d) δ 8.15 (dt, J = 8.5, 2.0 Hz, 2H), 8.07 (dt, J = 8.5, 2.0 Hz, 2H),
7.76-7.69 (m, 4H), 3.97 (s, 3H), 2.67 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.5, 166.8, 144.4, 144.2,
136.5, 130.2, 129.8, 129.0, 127.4, 127.2, 52.2, 26.7; MS (ESI): C16H15O3 ([M+H]+): calcd. 255.1, Found: 255.1.
1-(4'-Nitro-[1,1'-biphenyl]-4-yl)ethan-1-one (3ah).22 Yellow solid (212.1 mg, 88% yield); m.p. 150.2-152.1 (lit.22
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145.5-146.5 °C); H NMR (500 MHz, Chloroform-d) δ 8.35 (dt, J = 9.0, 2.5 Hz, 2H), 8.10 (dt, J = 8.0, 2.0 Hz, 2H),
8.00 (dt, J = 6.5, 3.0 Hz, 2H), 7.74 (dt, J = 9.0, 1.5 Hz, 2H), 2.68 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ
197.6, 147.6, 146.2, 143.1, 137.0, 129.1, 128.1, 127.6, 124.2, 26.7; MS (ESI): C14H12NO3 ([M+H]+): calcd. 242.1,
Found: 242.0.
Ethyl 4'-acetyl-[1,1'-biphenyl]-4-carboxylate (3bi).23 White solid (254.1 mg, 95% yield); m.p. 105.9-107.5 (lit.23
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106.7-107.7 °C); H NMR (500 MHz, Chloroform-d) δ 8.16 (dt, J = 8.5, 2.0 Hz, 2H), 8.07 (dt, J = 8.5, 2.0 Hz, 2H), 7.75-
7.69 (m, 4H), 4.43 (q, J = 7.0 Hz, 2H), 2.67 (s, 3H), 1.44 (t, J = 7.0 Hz, 3H); 13C{H} NMR (126 MHz, CDCl3) δ 197.6, 166.3,
144.5, 144.1, 136.5, 130.2, 129.0, 127.4, 127.2, 61.1, 26.7, 14.4; C17H17O3 ([M+H]+): calcd. 269.1, Found: 269.2.
Ethyl 4’-methyl-[1,1'-biphenyl]-4-carboxylate (3bb).24 White solid (288.2 mg, 95% yield); m.p. 70.7-72.5 °C
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(lit.23 75-76 °C); H NMR (500 MHz, Chloroform-d) δ 8.11 (dt, J = 8.5, 1.5 Hz, 2H), 7.66 (dt, J = 8.5, 2.0 Hz, 2H),
7.54 (dt, J = 8.5, 2.0 Hz, 2H), 7.29 (d, J = 8.0 Hz, 2H), 4.41 (q, J = 7.0 Hz, 2H), 2.43 (s, 3H), 1.43 (t, J = 7.0 Hz, 3H);
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13C{H} NMR (126 MHz, Chloroform-d) δ 166.6, 145.5, 138.1, 137.2, 130.0, 129.6, 129.0, 127.1, 126.8, 60.9, 21.2,
14.4; MS (ESI): C16H17O2 ([M+H]+): calcd. 241.1, Found: 241.2.
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4’-Methoxyl-[1,1'-biphenyl]-4-carbaldehyde (3cc).18 White solid (201.5 mg, 95% yield); m.p. 104.5-105.4 °C
(lit.18 104-105 °C); 1H NMR (500 MHz, Chloroform-d) δ 10.1 (s, 1H), 7.94 (dt, J = 8.5, 2.0 Hz, 2H), 7.73 (dt, J = 8.5,
2.0 Hz, 2H), 7.61 (dt, J = 8.5, 2.0 Hz, 2H), 7.03 (dt, J = 8.5, 2.0 Hz, 2H), 3.89 (s, 3H); 13C{H} NMR (126 MHz, Chlo-
roform-d) δ 191.8, 160.2, 146.8, 134.7, 132.1, 130.3, 128.5, 127.1, 114.5, 55.4; MS (ESI): C14H13O2 ([M+H]+): calcd.
213.1, Found: 213.1.
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4’-Fluoro-[1,1'-biphenyl]-4-carbaldehyde (3cd).25 White crystal (186.8 mg, 95% yield); m.p. 78.4-79.4 °C; H
NMR (500 MHz, Chloroform-d) δ 10.1 (s, 1H), 7.97 (dt, J = 8.5, 2.0 Hz, 2H), 7.72 (d, J = 8.0 Hz, 2H), 7.65-7.57 (m,
13
2H), 7.19 (tt, J = 9.0, 3.0 Hz, 2H); C{H} NMR (126 MHz, Chloroform-d) δ 191.8, 163.1 (d, J = 248.2 Hz), 146.1,
135.8 (d, J = 3.3 Hz), 135.2, 130.4, 129.0 (d, J = 8.3 Hz), 127.5, 116.0 (d, J =21.8 Hz); MS (ESI): C13H10FO ([M+H]+):
calcd. 201.1, Found: 201.1.
4-methyl-4’-nitro-1,1’-biphenyl (3db).26 Yellow solid (207.1 mg, 97% yield); m.p. 138.1-138.8 °C (lit.24 134-
135 °C); 1H NMR (500 MHz, Chloroform-d) δ 8.30 (dt, J = 9.0, 2.5 Hz, 2H), 7.74 (dt, J = 8.5, 2.5 Hz, 2H), 7.55 (dt, J
= 8.0, 2.0 Hz, 2H), 7.32 (dt, J = 7.5 Hz, 2H), 2.44 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 147.6, 146.9,
139.1, 135.9, 129.9, 127.5, 127.2, 124.1, 21.2; MS (ESI): C13H11NO2 ([M+H]+): calcd. 214.1, Found: 214.1.
4-methoxy-4’-(trifluoromethyl)-1,1'-biphenyl (3ec).24 Colorless oil (237.1 mg, 94% yield); H NMR (500 MHz,
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Chloroform-d) δ 7.76 (d, J = 8.0 Hz, 1H), 7.56 (t, J = 7.5, 1H), 7.46 (t, J = 8.0 Hz, 1H), 7.35 (d, J = 7.5 Hz, 1H),
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7.30-7.25 (m, 2H), 6.96 (dt, J = 9.0, 3.0 Hz, 2H), C{H} NMR (126 MHz, Chloroform-d) δ 159.2, 141.2 (q, J = 2.1
Hz), 132.3, 131.3, 130.1 (q, J = 1.6 Hz), 128.6 (q, J = 28.2 Hz), 126.1 (q, J = 5.4 Hz), 124.3 (q, J = 274.4 Hz), 113.2,
55.2; MS (ESI): C14H12F3O ([M+H]+): calcd. 253.1, Found: 253.0.
3-methoxy-4’-methyl-1,1’-biphenyl (3fb).24 Colorless oil (190.4 mg, 96% yield); 1H NMR (500 MHz, Chloroform-
d) δ 7.52 (dt, J = 8.5, 2.0 Hz, 2H), 7.37 (t, J = 8.0 Hz, 1H), 7.27 (d, J = 8.0 Hz, 2H), 7.20 (ddd, J = 7.5, 1.5, 1.0 Hz, 1H),
7.14 (dd, J = 2.5, 1.5 Hz, 1H), 6.90 (ddd, J = 8.0, 2.5, 1.0 Hz, 1H), 3.89 (s, 3H), 2.43 (s, 3H); 13C{H} NMR (126 MHz,
Chloroform-d) δ 159.9, 142.7, 138.2, 137.2, 129.7, 129.4, 127.0, 119.5, 112.7, 112.4, 55.2, 21.1; MS (ESI): C14H15O
([M+H]+): calcd. 198.1, Found: 199.2.
4-methoxy-1,1’-biphenyl (3gc).18 White solid (171.3 mg, 93% yield); m.p. 86.2-87.4 °C (lit.18 87-88 °C); 1H NMR
(500 MHz, Chloroform-d) δ 7.60-7.53 (m, 4H), 7.46-7.41 (m, 2H), 7.35-7.30 (m, 1H), 7.00 (dt, J = 9.0, 3.0 Hz, 2H),
3.87 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 159.2, 140.9, 133.8, 128.7, 128.2, 126.7, 126.7, 114.2, 55.4;
MS (ESI): C13H13O ([M+H]+): calcd. 185.1, Found: 185.1.
N-(4’-methoxy-[1,1’-biphenyl]-4-yl)acetamide (3hc). White solid (200.5 mg, 83% yield); m.p. 206.8-207.6 °C; 1H
NMR (500 MHz, Chloroform-d) δ 7.56 (d, J = 8.5, 2H), 7.54-7.49 (m, 4H), 6.98 (d, J = 8.5, 2H), 7.23 (br, 1H), 3.86 (s,
3H), 2.22 (s, 3H); 13C{H} NMR (126 MHz, DMSO-d6) δ 168.2, 158.5, 138.1, 134.4, 132.2, 127.2, 126.3, 119.3, 114.3,
55.1, 24.0; HRMS (ESI): C15H15NNaO2 ([M+Na]+): calcd. 264.0995, Found: 264.1004.
N-(4’-methyl-[1,1'-biphenyl]-2-yl)acetamide (3ib).27 Yellow solid (214.3 mg, 95% yield); m.p. 105.2-106.1 °C
(lit.25 103 °C); H NMR (500 MHz, Chloroform-d) δ 8.29 (d, J = 8.0 Hz, 1H), 7.39-7.34 (m, 1H), 7.33-7.22 (m, 4H),
1
7.18 (t, J = 7.0 Hz, 2H), 2.44 (s, 3H), 2.04 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 168.2, 137.8, 135.1,
134.8, 132.1, 130.1, 129.8, 129.1, 128.2, 124.3, 121.5, 24.6, 21.2; MS (ESI): C15H16NO ([M+H]+): calcd. 226.1, Found:
226.0.
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4-methoxy-4’-methyl-1,1'-biphenyl (3jb).28 White solid (172.5 mg, 87% yield); m.p. 110.1-111.9 °C (lit.26 107.9-
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108.1 °C); 1H NMR (500 MHz, Chloroform-d) δ 7.53 (dt, J = 9.5, 3.0 Hz, 2H), 7.47 (dt, J = 8.0, 2.0 Hz, 2H), 7.53 (d, J
= 8.0 Hz, 2H), 7.25 (dt, J = 9.0, 3.0, 2H), 3.87 (s, 3H), 2.40 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 159.0,
138.0, 136.3, 133.8, 129.4, 128.0, 126.6, 114.2, 55.3, 21.1; MS (ESI): C14H15O ([M+H]+): calcd. 199.1, Found: 199.1.
4’-methoxyl-[1,1’-biphenyl]-4-amine (3lc).29 White solid (182.1 mg, 91% yield); m.p. 144.9-145.3 °C (lit.27
145 °C) ; 1H NMR (500 MHz, Chloroform-d) δ 7.47 (dt, J = 8.5, 2.0 Hz, 2H), 7.38 (dt, J = 8.5, 2.5 Hz, 2H), 6.96 (dt, J
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= 8.5, 3.0 Hz, 2H), 7.26 (dt, J = 8.5, 2.5, 2H), 3.85 (s, 3H), 3.71 (br, 2H); C{H} NMR (126 MHz, Chloroform-d) δ
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158.4, 145.3, 133.9, 131.4, 127.6, 127.4, 115.4, 114.1, 55.3; MS (ESI): C13H14N ([M+H]+): calcd. 184.1, Found: 184.1.
2-phenylpyridine (3ma).30 Colorless oil (139.3 mg, 90% yield); 1H NMR (500 MHz, Chloroform-d) δ 8.72 (dt, J =
5.0, 1.0 Hz, 1H), 8.04-7.98 (m, 2H), 7.80-7.72 (m, 2H), 7.53-7.47 (m, 2H), 7.46-7.40 (m, 1H), 7.27-7.21 (m, 1H);
13C{H} NMR (126 MHz, Chloroform-d) δ 157.5, 149.6, 139.4, 136.8, 129.0, 128.7, 127.0, 122.1, 120.6; MS (ESI):
C11H10N ([M+H]+): calcd. 156.1, Found: 156.2.
2-(4-methoxyphenyl)pyridine (3mc).28 White solid (176.5 mg, 95% yield); m.p. 52.9-54.4 °C (lit.26 53.2-53.9 °C);
1H NMR (500 MHz, Chloroform-d) δ 8.67 (dq, J = 5.0, 1.0 Hz, 1H), 7.97 (dt, J = 9.0, 3.0 Hz, 2H), 7.76-7.66 (m, 2H),
7.21-7.15 (m, 1H), 7.01 (dt, J = 8.5, 3.0 Hz, 2H), 3.88 (s, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 160.5, 157.1,
149.4, 136.7, 131.9, 128.2, 121.4, 119.9, 114.2, 55.4; MS (ESI): C12H12NO ([M+H]+): calcd. 186.1, Found: 186.2.
Ethyl 4-([1,1'-biphenyl]-4-yl)-4-oxobutanoate (3na).31 White solid (254.7 mg, 91% yield); m.p. 81.5-82.3 °C
(lit.31 80.6-82.1 °C); 1H NMR (500 MHz, Chloroform-d) δ 8.08 (dt, J = 8.5, 3.0 Hz, 2H), 7.71 (dt, J = 8.5, 2.0 Hz, 2H),
7.67-7.63 (m, 2H), 7.52 – 7.46 (m, 2H), 7.42 (tt, J = 7.5, 1.5 Hz, 1H), 4.19 (q, J = 7.0 Hz, 2H), 3.37 (t, J = 6.5 Hz, 2H),
2.80 (t, J = 6.5 Hz, 2H), 1.30 (t, J = 7.0 Hz, 3H); 13C{H} NMR (126 MHz, Chloroform-d) δ 197.7, 172.9, 145.9, 139.8,
135.3, 128.9, 128.6, 128.2, 127.2, 127.2, 60.7, 33.4, 28.4, 14.2; MS (ESI): C18H19O3 ([M+H]+): calcd. 283.1, Found:
283.1.
AUTHOR INFORMATION
Corresponding Author
* E-mail for W.K.S.: pharmlab@zjut.edu.cn.
* E-mail for Z.H.L.: lizhenhua@zjut.edu.cn.
The authors declare no competing financial interest.
ACKNOWLEDGMENT
We gratefully acknowledge the Special Program for Key Basic Research of the Ministry of Science and Technology of
China (No. 2014CB460608) and the National Natural Science Foundation of China (Nos. 21376221, 21406201 and
21506190) for financial support. We also thank Prof. Yi-Yi Weng, Dr. Wei Shi, and Dr. Feng-Fan Liu at Zhejiang
University of Technology for helpful discussion, and Mr. Chao Zhang and Miss Qiao-Ling Shao for technical assis-
tance.
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ASSOCIATED CONTENT
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Supporting Information.
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The Supporting Information is available free of charge on the ACS Publications website at DOI:
Reaction optimization studies, 1H and 13C NMR data (PDF)
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REFERENCES
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12. η represents the mass ratio of liquid additive used (volume) to the mass of other materials including reagents and
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16. Further optimization showed the usage of catalytic system could be reduce to 2 mol%, which grinding time was
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