Recyclable Bismuth Complex Catalyzed 1,6-Conjugate Addition of Various Nucleophiles to para-Quinone Methides: Expedient Access to Unsymmetrical Diaryl- and Triarylmethanes

Article abstract of DOI:10.1002/ejoc.201901732

An efficient method for the 1,6-conjugate addition of para-quinone methides with readily available nucleophiles was developed. This protocol provides a straightforward access to a class of diaryl and triarylmethane derivatives with good to excellent yields in the presence of (C₄H₁₂N₂)₂[BiCl₆]Cl·H₂O. Moreover, this bismuth catalyst can be recycled for several times.

Full text of DOI:10.1002/ejoc.201901732

A Journal of
Accepted Article
Title: Recyclable bismuth complex catalyzed 1,6-conjugate addition of
various nucleophiles to para-quinone methides: expedient access
to unsymmetrical diaryl- and triarylmethanes
Authors: Xianghao Liang, Haiyan Xu, Hanlin Li, Lizhuang Chen, and
Hongfei Lu
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201901732
Link to VoR: http://dx.doi.org/10.1002/ejoc.201901732
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10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
Recyclable bismuth complex catalyzed 1,6-conjugate addition of
various nucleophiles to para-quinone methides: expedient access
to unsymmetrical diaryl- and triarylmethanes
Xianghao Liang,† Haiyan Xu,†* Hanlin Li, Lizhuang Chen and Hongfei Lu*
Abstract: An efficient method for the 1,6-conjugate addition of para-
quinone methides with readily available nucleophiles was developed.
This protocol provides straightforward access to a class of diaryl and
triarylmethane derivatives with good to excellent yields in the
presence of (C4H12N2)2[BiCl6]Cl·H2O. Moreover, this bismuth catalyst
can be recycled for several times.
Mannich.[14] and ring opening of epoxides reactions.[15] Notably,
this bismuth complex is easy-to-prepare and stable storage.
Related
bismuth
complex
{(C5H6N4O)(C5H4N4)3(C5H4N4O)[Bi2Cl11]Cl2} also has been
designed and successfully applied in the one pot three-
component Biginelli reaction.[16]
In continuation of our research interests,[14-16] we assumed
that using
a green and reusable heterogeneous bismuth
complex as a catalyst for the synthesis of functionalized diaryl
and triarylmethane derivatives through 1,6-conjugate addition of
p-QMs. To our surprise, we disclose that the air-stable and
recoverable bismuth complex {(C4H12N2)2[BiCl6]Cl·H2O} showed
high catalytic activities in the 1,6-conjugate addition of p-QMs
under the mild reaction conditions. This methodology was
compatible with several functional nucleophiles and afforded the
corresponding products with good to excellent yields. Notably,
this novel bismuth complex can be recycled six times by simple
isolation procedures and without catalytic activities decreasing.
Herein, we report our results.
Introduction
Para-quinone methides (p-QMs) are prevalent structural
skeletons in a broad array of synthetic bioactive molecules,
natural products and pharmaceuticals. Moreover, the p-QMs
have been widely studied as an important and readily available
class of synthetic intermediates, owing to their unique structural
features.[1] The p-QMs have the zwitterionic resonance structure
of a cyclohexadiene moiety in para-conjugation with a carbonyl
group, which enable them to be a good candidate for 1,6-
conjugate addition, [4+1]-cycloaddition,[2] [4+2]-cycloaddition,[3]
[3+2]-cycloaddition[4] and so on. In recent years, various catalytic
system have been designed for 1,6-conjugate addition of p-QMs,
such as BF3·OEt,[5] B(C6F5)3,[6] Phosphine,[7] copper salts,[8]
Fe(acac)3,[9] Fe(OTf)3,[10] Bi(OTf)3,[11] as well as some chiral
catalysts[12]. However, all these catalysts have limited substrates
scope and are difficulty in recycling. Therefore, the development
of high efficient strategies for the synthesis of diaryl and
triarylmethane derivatives in a green manner through 1,6-
conjugate addition of p-QMs has attracted considerable
attention.[13]
Bismuth is known as a low cost, environmentally benign,
easy handle element and its bismuth(III) salts has been widely
used as Lewis acid catalysts in organic chemistry. Very recently,
Li Xin group have reported Bi(OTf)3 catalyzed 1,6-conjugate
addition of p-QMs with 3-propenyl-2-silyloxyindoles and
allylboronic acid pinacol ester to synthesize diphenylmethane
type compounds.[11a] Anand group has reported Bi(OTf)3
catalyzed intermolecular 1,6-hydroolefination of p-QMs with
styrenes.[11b] However, the Bi(OTf)3 is difficult to be separated
from the reaction and be reused. A novel heterogeneous
bismuth complex formed by BiCl3 and piperazine has been
designed, synthesized and characterized in our group and been
used as an efficient and recyclable catalyst for three-component
Results and Discussion
For the initial study, p-QM (1a) and p-methylbenzenethiol 2a
were selected as model substrates to optimize the reaction
conditions (Table 1). As expected, the model reaction did not
occur without the catalyst (Table 1, entry 1). To our delight, it
was found that the 10 mol% (C4H12N2)2[BiCl6]Cl·H2O could be
efficient to promote the model reaction and afforded the desired
product 3aa in excellent yield (98%) within 4 h. While other
commercial available bismuth salts, such as BiCl3 and Bi(OTf)3,
were examined on the same reaction conditions, the yields of
the product were obtained in 76% and 72%, respectively (Table
1, entries 3 and 4 ). We also screened other commonly utilized
Lewis acid catalysts, such as FeCl3, Fe(OTf)3, Cu(OTf)2,
Ni(OTf)2, Sc(OTf)3 and AlCl3, no better results were obtained
(Table 1, entries 5-10). We subsequently investigated the
solvent effect by employing different solvents including MeOH,
1,4-dioxane, toluene and chloroform (CHCl3) , but less than 98%
yield was observed (Table 1, entries 11-14). Reducing the
catalyst loading from 10 mol% to 5 mol% or 8 mol% results in
lower yields of the desired product (36% and 75%), respectively
(Table 1, entries 15 and 16).
Table 1 Conditions screening[a]
[a]
School of Environmental and Chemical Engineering, Jiangsu University of
Science and Technology, Zhenjiang, Jiangsu 212003, China
E-mail: xuhaiyanjurong@163.com, zjluhf1979@just.edu.cn
These authors contributed equally to this work.
X. Liang, Dr. H. Xu,* H. Li, Prof. L. Chen and Prof. H. Lu*
†
Supporting information for this article is given via a link at the end of the
document.((Please delete this text if not appropriate))
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10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
corresponding products 3ma and 3na were obtain in 95% and
91% yield, respectively.
Entry
1
Catalyst
-
Solvent
DCM
Yield (%)[b]
0
2[c]
[Bi]
DCM
98
76
72
53
85
83
70
79
55
47
83
84
87
36
75
3
BiCl3
DCM
4
Bi(OTf)3
FeCl3
DCM
5
DCM
6
Fe(OTf)3
Cu(OTf)2
Ni(OTf)2
Sc(OTf)3
AlCl3
DCM
7
DCM
8
DCM
9
DCM
10
11
12
13
14
15
16
DCM
[Bi]
MeOH
1,4-Dioxane
Toluene
CHCl3
DCM
[Bi]
[Bi]
[Bi]
[Bi] (5 mol%)
[Bi] (8 mol%)
DCM
[a] Reaction conditions: p-QM (1a) (0.5 mmol), 4-methylbenzenethiol (2a) (1
mmol), Solvent (2 mL). [b] Isolated yield based on p-QM as limiting reagent.
[c]The bismuth complex [Bi] refers to (C4H12N2)2[BiCl6]Cl·H2O.
With optimized reaction conditions in hand, we examined
the substrate scope of this addition reaction by using various p-
QMs (1) and related thiols (2). As illustrated in Scheme 1, the
Scheme 1. Bismuth complex [Bi] catalyzed 1,6-conjugate addition of p-QMs
with a variety of thiols. The yield given in each case is the isolated product of a
reaction carried out on a 0.5 mmol scale at standard conditions.
1,6-conjugate addition of p-QMs with
a variety of thiols
performed well in the presence of bismuth complex as catalysis.
The p-QMs with electron-donating groups, such as methyl and
methoxy, reacted well with 4-methylbenzenethiol (2a) to provide
the expected products 3ba and 3ca in yields of 97% and 93%
within 4 h, respectively. The p-QMs (1d-f) containing a strong
electron-withdrawing group were also amenable to this protocol,
providing the desired products (3da-3fa) in good yield. The p-
QMs derived from the halo-substituted aromatic aldehydes (1g-i)
exhibited high relativity under the standard conditions, and the
corresponding products (3ga-3ia) were produced in yields
ranging from 94-97%. The reaction reacted smoothly in case of
p-QMs derived from other electron-rich arenes, such as 1-
naphthaldehyde (1k) and thiophene-2-carbaldehyde (1l), gave
the adduct 3ka and 3la in 93% and 91% yield, respectively.
Moreover, the scope of this protocol was extended to a wide
variety of aromatic and aliphatic thiols under the optimized
reaction conditions. As expected, the reaction worked quite well
utilizing electron-rich thiophenols substrates (2b-f), and affording
the related products in good to excellent yields (88-94%).
Additional, the efficacy of this protocol was also examined with
naphthalene-2-thiol, and in this case, the product (3ag) was
obtained in 91% isolated yield. Furthermore, the aliphatic thiols,
such as phenylmethanethiol (2h) and 2-mercaptoethanol (2i),
were also proved to be effective candidates for the 1,6-
conjugate addition of p-QM, leading to excellent yield of the
products 3ah and 3ai. It should be pointed out that our method
also allows for the 1,6-conjugate addition of p-QMs with
thiolacetic acid (2j). Additionally, when the methyl (isopropyl)
group was modified on the  and ’- position in p-QM, the
Encouraged by the above successful access to diarylmethyl
thioethers and based on our previous results[17], we were eager
to know if this method was suitable for the decarboxylative
addition of β-ketoacids to p-QMs. To our delight, a variety of β-
ketoacids were also subjected to this protocol (Scheme 2).
However, electronic effects of the aryl substituents in β-
ketoacids have a significant effect on the results of this reaction.
The β-ketoacids with electron-rich group, such as methoxy, gave
the desired product (5ab) in 98% yield. While the presence of a
strong electron-withdrawing group (NO2 or CF3) at the para
position of 3-oxo-3-phenylpropanoic acid, namely 3-(4-
nitrophenyl)-3-oxopropanoic acid
(4c) and
3-oxo-3-(4-
(trifluoromethyl)phenyl)propanoic acid (4d), the reactions did not
work, presumably owing to their lability.[18] The presence of a
weak electron-withdrawing group such as chloride at para
position of 3-oxo-3-phenylpropanoic acid obviously decreased
the reactivity, the expected product (5ae) was obtained with 87%
yield. After the examination of the substrate scope of β-
ketoacids, we then explored the scope of p-QMs. It is evident
from the Scheme 2 that a series of para-substituted electron-rich
and deficient p-QMs could work quite well under standard
reaction conditions, leading to the expected products in the yield
ranging from 47% to 96%. Notably, this protocol could be
applicable to the aliphatic (methyl) β-ketoacid (4f), in which the
desired product 5af was obtained in moderate yield (49%).
Furthermore, some control experiments were performed to gain
insight of the reaction mechanism (Scheme S1), and the
experiment results indicate that 1,6-addition step takes place
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10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
prior to the decarboxylation step in this decarboxylative addition
process (Scheme S2).
Scheme 3. Bismuth complex [Bi] catalyzed 1,6-conjugate addition of p-QMs
with naphthalen-2-ol. The yield given in each case is the isolated product of a
reaction carried out on a 0.25 mmol scale at the standard conditions.
To demonstrate the general application and robustness of
this protocol, gram-scale reactions were also investigated as
shown in Scheme 4. To our delight, the desired product 3ai was
obtained in 98% yield in the presence of 5 mol% [Bi] catalyst
and without need of excessive 2-mercaptoethan-1-ol (2i).
Furthermore, a large scare reaction of 2,6-di-tert-butyl-4-(4-
nitrobenzylidene)cyclohexa-2,5-dien-1-one (1d) with one equiv.
of naphthalen-2-ol (6) was carried under the standard reaction
conditions. The correspond triarylmethane 1-((3,5-di-tert-butyl-4-
hydroxyphenyl)(4-nitrophenyl)methyl)naphthalen-2-ol (7d) was
obtained in 62% yield, albeit with longer reaction time (48 h).
Scheme 2. Bismuth complex [Bi] catalyzed 1,6-conjugate addition of p-QMs
with various β-ketoacids. The reactions were carried out with 1 (0.25 mmol), 4
(0.5 mmol) and 10 mol% [Bi] catalyst in dichloromethane (2.0 ml) at room
temperature for 3 hours (the conversion of 1 was completed), then 10 mol%
Et3N was added into the reaction mixture.
On the other hand, the triarylmethane framework represent
an important structural motif widely found in natural products
and used in pharmaceuticals.[19] We thus considered to
investigate the 1,6-conjugate addition of p-QMs with naphthol to
construct diversely unsymmetrical triarylmethanes with this
standard reaction conditions. Gratifyingly, this protocol was
found to be amenable for naphthol (6). As represented in
Scheme 3, a series of p-QMs that bear electron-donating and
electron-deficient aromatic moieties performed quite well with
naphthalen-2-ol to afford triarylmethane derivatives in good to
excellent yields (up to 98%). It is notable that the p-QMs bearing
a strong electron-withdrawing group, such as 2,6-di-tert-butyl-4-
(4-nitrobenzylidene)cyclohexa-2,5-dien-1-one
(1d),
was
converted into corresponding product (7d) in 93% yield within a
very short time (4 h). Meanwhile, the p-QMs (1H, 1I and 1j) with
a halogen (or hydroxyl) substituent at 2-position demonstrated
much higher efficient to give the desired products (7H, 7I and 7j)
in excellent yields (up to 98%), presumably owing to the effect of
hydrogen bonding. This transformation was also effective for the
synthesis of naphthalene-, thiophen-, and indole-substituted
triarylmethane products 7k, 7l, and 7m from the related p-QMs.
Scheme 4. Gram-scale experiments.
To show the high efficiency and utility of this heterogeneous
[Bi] catalyst, attempt was made to recycle this catalytic system.
The 1,6-conjugate addition of p-QM (1a) with p-methylthiophenol
(2a) under the optimized reaction conditions described in Table
1 with the [Bi] complex as catalyst was examined. The [Bi]
catalyst could be recovered just by simple procedure of filtration,
and then washed with DCM after the reaction was completed.
As depicted in Figure 1, the easily recovered catalyst can be
reused without further process, and showing no significant
degrease of catalytic activity in a test of six cycles (up to 90%
yield) (Table S1).
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10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
chromatography with ethyl acetate and petroleum ether (1:100)
as eluents to afford pure product.
2,6-di-tert-butyl-4-[phenyl(p-tolylthio)methyl]phenol
(3aa):
(204 mg, 98%). Pale yellow solid; m.p. = 101 - 102 oC. H NMR
(400 MHz, Chloroform-d) δ 7.51 – 7.45 (m, 2H), 7.34 – 7.28 (m,
2H), 7.25 – 7.19 (m, 1H), 7.14 (d, J = 6.9 Hz, 4H), 6.99 (d, J =
7.9 Hz, 2H), 5.40 (s, 1H), 5.13 (s, 1H), 2.28 (s, 3H), 1.40 (s,
18H). 13C NMR (100 MHz, Chloroform-d) δ 152.93, 141.92,
136.91, 135.76, 132.62, 132.19, 131.78, 129.49, 128.54, 128.45,
127.04, 125.27, 58.72, 34.49, 30.39, 21.17. FT-IR (neat): 3633,
2955, 1599, 1491, 1433, 1234, 1153, 802, 699 cm-1. MS: Calcd
for C28H34OS: [M+H]+ 419.2; Found, 419.2.
1
2,6-di-tert-butyl-4-[p-tolyl(p-tolylthio)methyl]phenol
(3ba):
(105 mg, 97%). Pale yellow solid. m.p. = 104 - 105 oC. The
reaction was performed with 77 mg of 1b (0.25 mmol), dissolved
in 2 mL of CH2Cl2. 1H NMR (400 MHz, Chloroform-d) δ 7.73 (d, J
= 7.7 Hz, 1H), 7.24 – 7.19 (m, 1H), 7.16 – 7.09 (m, 6H), 6.99 (d,
J = 7.9 Hz, 2H), 5.59 (s, 1H), 5.11 (s, 1H), 2.32 (s, 3H), 2.27 (s,
3H), 1.38 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 152.81,
139.84, 136.65, 135.80, 135.66, 131.45, 130.98, 130.50, 129.52,
128.40, 126.96, 126.28, 125.53, 54.83, 34.46, 30.40, 21.16,
19.90. FT-IR (neat): 3634, 2954, 1601, 1490, 1432, 1234, 1152,
801, 735 cm-1. MS: Calcd for C29H36OS: [M+H]+ 433.2; Found,
433.2.
Figure 1. Recycling Catalyst (C4H12N2)2[BiCl6]ClH2O
Conclusions
In conclusion, we have developed a highly effective method
for the synthesis of diaryl and triarylmethane derivatives through
bismuth complex catalyzed 1,6-conjugate addition of commonly
utilized nucleophiles to p-QMs. The key features of this protocol
include broad substrate scope, high yields of products and 100%
atom economy. What’s more, the bismuth complex is non-toxic,
air-stable and can also be efficiently recycled for multi-times as a
catalyst. Further studies including the design novel chiral
bismuth complexes and an asymmetric version are underway in
our laboratory.
2,6-di-tert-butyl-4-[(4-methoxyphenyl)(p-tolylthio)methyl]
phenol (3ca): (111 mg, 93%). Yellow gummy. The reaction was
performed with 81 mg of 1c (0.25 mmol), dissolved in 2 mL of
CH2Cl2. 1H NMR (400 MHz, Chloroform-d) δ 7.39 – 7.35 (m, 2H),
7.12 (d, J = 8.2 Hz, 4H), 6.98 (d, J = 7.6 Hz, 2H), 6.85 – 6.81 (m,
2H), 5.36 (s, 1H), 5.11 (s, 1H), 3.79 (s, 3H), 2.27 (s, 3H), 1.39 (s,
18H). 13C NMR (100 MHz, Chloroform-d) δ 158.60, 152.86,
135.71, 134.06, 132.10, 132.04, 129.58, 129.47, 125.19, 113.83,
58.05, 55.37, 34.48, 30.39, 21.18. FT-IR (neat): 3592, 2970,
1609, 1512, 1431, 1235, 1111, 1026, 809, 739 cm-1. MS: Calcd
for C29H36O2S: [M+H]+ 449.2; Found, 449.2.
Experimental Section
General information: 1H NMR spectra were acquired on Bruker
400 MHz spectrometers and chemical shifts were recorded
relative to tetramethylsilane (TMS, δ = 0.00) or residual protiated
solvent CDCl3 (δ = 7.26). 13C NMR spectra were obtained at 100
MHz instrument and chemical shifts were recorded relative to
solvent resonance CDCl3 (δ = 77.16). Melting points were
recorded on RY-51 melting point apparatus. FT-IR spectra were
recorded on an iS50 FT-IR spectrometer and are uncorrected.
LCMS analysis was conducted on an Agilent 6110 and 6520.
Flash column chromatography was performed using silica gel
(200–300 mesh) under pressure. Analytical thin layer
chromatography (TLC) was carried out using GF254 commercial
silica gel plates. Unless otherwise stated, all reagents and
solvents were used without further purification.
2,6-di-tert-butyl-4-[(4-nitrophenyl)(p-tolylthio)methyl]phenol
(3da): (212 mg, 92%). Yellow gummy. 1H NMR (400 MHz,
Chloroform-d) δ 8.15 – 8.11 (m, 2H), 7.60 – 7.56 (m, 2H), 7.14 –
7.10 (m, 2H), 7.09 (s, 2H), 6.99 (d, J = 7.8 Hz, 2H), 5.43 (s, 1H),
5.19 (s, 1H), 2.27 (s, 3H), 1.39 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 153.41, 149.75, 146.94, 137.81, 136.29, 132.65,
131.24, 130.16, 129.80, 129.39, 125.10, 123.72, 58.32, 34.55,
30.34, 21.20. FT-IR (neat): 3631, 2956, 1594, 1520, 1434, 1344,
1153, 809, 702 cm-1. MS: Calcd for C28H33NO3S: [M+H]+ 464.2;
Found, 464.2.
2,6-di-tert-butyl-4-{(p-tolylthio)[4-(trifluoromethyl)phenyl]
methyl}phenol (3ea): (103 mg, 85%). Yellow gummy. The
reaction was performed with 91 mg of 1e (0.25 mmol), dissolved
General method for the 1,6-conjugate addition reaction of p-
QMs with thiol (2)
1
p-QMs (0.5 mmol), (C4H12N2)2[BiCl6]Cl·H2O (10 mol%) and
in 2 mL of CH2Cl2. H NMR (400 MHz, Chloroform-d) δ 7.59 –
thiol (1 mmol) were placed into
a flask. To the flask,
7.51 (m, 4H), 7.15 – 7.09 (m, 4H), 7.00 (d, J = 7.9 Hz, 2H), 5.41
(s, 1H), 5.17 (s, 1H), 2.28 (s, 3H), 1.40 (s, 18H). 13C NMR (100
MHz, Chloroform-d) δ 153.22, 146.16, 137.43, 136.05, 132.39,
131.82, 130.84, 129.68, 128.84, 125.4, 125.15, 58.37, 34.52,
30.35, 21.20. FT-IR (neat): 3638, 2958, 1434, 1323, 1236, 1123,
dichloromethane (DCM, 2 mL) was added. Then the mixture was
stirred at room temperature, until p-QMs was completely
consumed as indicated by TLC analysis. After the completion of
reaction, the residue was directly purified by flash column
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10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
1067, 907, 733 cm-1. MS: Calcd for C29H33F3OS: [M+H]+ 487.2;
Found, 487.2.
NMR (400 MHz, Chloroform-d) δ 8.19 – 8.14 (m, 1H), 7.92 –
7.84 (m, 2H), 7.78 – 7.74 (m, 1H), 7.51 – 7.44 (m, 3H), 7.17 (s,
2H), 7.14 – 7.09 (m, 2H), 6.98 – 6.94 (m, 2H), 6.19 (s, 1H), 5.10
(s, 1H), 2.25 (s, 3H), 1.35 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 152.91, 136.96, 136.58, 135.73, 134.17, 133.32,
131.44, 131.25, 131.18, 129.56, 128.97, 127.99, 126.58, 126.13,
125.56, 125.53, 123.87, 54.65, 34.47, 30.40, 21.13. FT-IR (neat):
3631, 2956, 1596, 1491, 1433, 1234, 1154, 779, 739 cm-1. MS:
Calcd for C32H36OS: [M+H]+ 469.2; Found, 469.2.
4-[(3,5-di-tert-butyl-4-hydroxyphenyl)(p-tolylthio)methyl]
benzonitrile (3fa): (101 mg, 91%). Pale yellow solid. m.p. = 111
- 112 oC. The reaction was performed with 80 mg of 1f (0.25
mmol), dissolved in 2 mL of CH2Cl2. 1H NMR (400 MHz,
Chloroform-d) δ 7.55 (q, J = 8.5 Hz, 4H), 7.13 – 7.09 (m, 2H),
7.07 (s, 2H), 6.99 (d, J = 7.9 Hz, 2H), 5.39 (s, 1H), 5.19 (s, 1H),
2.28 (s, 3H), 1.39 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ
153.34, 147.62, 137.69, 136.18, 132.57, 132.28, 131.35, 130.27,
129.74, 129.31, 125.10, 119.01, 110.79, 58.51, 34.52, 30.32,
21.21. FT-IR (neat): 3633, 2957, 1434, 1361, 1236, 907, 810,
730, 555 cm-1. MS: Calcd for C29H33NOS: [M+H]+ 444.2; Found,
444.2.
2,6-di-tert-butyl-4-[thiophen-2-yl(p-tolylthio)methyl]phenol
(3la): (192 mg, 91% ). Orange gummy. 1H NMR (400 MHz,
Chloroform-d) δ 7.21 – 7.19 (m, 1H), 7.16 (d, J = 7.7 Hz, 4H),
7.01 (d, J = 7.9 Hz, 2H), 6.93 – 6.87 (m, 2H), 5.53 (s, 1H), 5.15
(s, 1H), 2.29 (s, 3H), 1.40 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 153.22, 146.54, 137.62, 135.82, 133.28, 131.87,
131.61, 129.52, 126.54, 125.97, 125.12, 125.00, 54.45, 34.49,
30.39, 21.24. FT-IR (neat): 3626, 2954, 1610, 1433, 1238, 1152,
810, 737 cm-1. MS: Calcd for C26H32OS2: [M+H]+ 425.1; Found,
425.1.
2,6-di-tert-butyl-4-[(4-fluorophenyl)(p-tolylthio)methyl]
phenol (3ga): (212 mg, 97% ). Pale yellow solid. m.p. = 92 - 93
oC. 1H NMR (400 MHz, Chloroform-d) δ 7.43 – 7.38 (m, 2H),
7.13 – 7.08 (m, 4H), 7.03 – 6.93 (m, 4H), 5.37 (s, 1H), 5.14 (s,
1H), 2.27 (s, 3H), 1.38 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 163.10, 160.66, 153.03, 137.73 (137.69),
137.14, 135.89, 132.32, 132.28, 131.54, 130.16, 130.08, 129.57,
125.18, 115.34, 115.13, 57.95, 34.51, 30.38, 21.18. FT-IR (neat):
3634, 2955, 1602, 1505, 1433, 1224, 1155, 1120, 1016, 797,
738 cm-1. MS: Calcd for C28H33FOS: [M+H]+ 437.2; Found, 437.2.
2,6-di-tert-butyl-4-{[(4-methoxyphenyl)thio](phenyl)methyl}
phenol (3ab): (196 mg, 90%). Pale yellow solid. m.p. = 104 -
105 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.44 – 7.40 (m, 2H),
7.32 – 7.26 (m, 2H), 7.23 – 7.19 (m, 1H), 7.17 – 7.13 (m, 2H),
7.10 (s, 2H), 6.72 – 6.68 (m, 2H), 5.27 (s, 1H), 5.11 (s, 1H), 3.74
(s, 3H), 1.38 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ
159.43, 152.87, 141.97, 135.70, 135.24, 132.75, 131.81, 128.55,
128.38, 127.00, 125.24, 114.76, 114.28, 59.78, 55.31, 34.46,
30.39. FT-IR (neat): 3627, 2954, 1590, 1491, 1433, 1243, 1171,
1030, 824, 699 cm-1. MS: Calcd for C28H34O2S: [M+H]+ 435.2;
Found, 435.2.
2,6-di-tert-butyl-4-[(4-chlorophenyl)(p-tolylthio)methyl]
phenol (3ha): (214 mg, 95%). Pale yellow solid. m.p. = 123 -
124 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.42 – 7.38 (m, 2H),
7.31 – 7.26 (m, 2H), 7.15 – 7.09 (m, 4H), 7.01 (d, J = 7.9 Hz,
2H), 5.37 (s, 1H), 5.16 (s, 1H), 2.29 (s, 3H), 1.40 (s, 18H). 13C
NMR (100 MHz, Chloroform-d) δ 153.08, 140.58, 137.20, 135.94,
132.72, 132.29, 132.13, 131.25, 129.91, 129.61, 128.57, 125.14,
58.06, 34.51, 30.38, 21.19. FT-IR (neat): 3633, 2954, 1596,
1488, 1433, 1234, 1152, 1090, 808, 738 cm-1. MS: Calcd for
C28H33ClOS: [M+H]+ 453.2; Found, 453.2.
2,6-di-tert-butyl-4-{[(4-fluorophenyl)thio](phenyl)methyl}
phenol (3ac): (199 mg, 94%). Pale yellow solid. m.p. = 92 - 93
oC. 1H NMR (400 MHz, Chloroform-d) δ 7.45 – 7.40 (m, 2H),
7.31 – 7.27 (m, 2H), 7.24 – 7.16 (m, 3H), 7.11 (s, 2H), 6.89 –
6.82 (m, 2H), 5.34 (s, 1H), 5.13 (s, 1H), 1.38 (s, 18H). 13C NMR
(100 MHz, Chloroform-d) δ 163.59, 161.14, 153.05, 141.54,
135.89, 134.80, 134.72, 131.36, 131.10 (131.07), 128.53,
127.22, 125.26, 115.85, 115.63, 59.32, 34.51, 30.40. FT-IR
(neat): 3633, 2956, 1589, 1489, 1434, 1233, 1154, 1120, 827,
700 cm-1. MS: Calcd for C27H31FOS: [M+H]+ 423.2; Found, 423.2.
4-[(4-bromophenyl)(p-tolylthio)methyl]-2,6-di-tert-
butylphenol (3ia): (232 mg, 94%). Pale yellow solid. m.p. = 130
o
1
- 131 C. H NMR (400 MHz, Chloroform-d) δ 7.43 – 7.37 (m,
2H), 7.34 – 7.30 (m, 2H), 7.13 – 7.06 (m, 4H), 6.99 (d, J = 7.9
Hz, 2H), 5.33 (s, 1H), 5.14 (s, 1H), 2.27 (s, 3H), 1.38 (s, 18H).
13C NMR (100 MHz, Chloroform-d) δ 153.09, 141.12, 137.21,
135.96, 132.28, 132.10, 131.52, 131.17, 130.27, 129.61, 125.13,
120.86, 58.12, 34.51, 30.38, 21.19. FT-IR (neat): 3632, 2954,
1597, 1484, 1433, 1234, 1152, 1071, 1010, 808, 738 cm-1. MS:
Calcd for C28H33BrOS: [M+H]- 497.1; Found, 497.1.
2,6-di-tert-butyl-4-{[(4-chlorophenyl)thio](phenyl)methyl}
phenol (3ad): (199 mg, 91%). Pale yellow solid. m.p. = 126 -
127 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.47 – 7.43 (m, 2H),
7.32 – 7.28 (m, 2H), 7.25 – 7.20 (m, 1H), 7.12 (d, J = 4.4 Hz,
6H), 5.42 (s, 1H), 5.15 (s, 1H), 1.38 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 153.11, 141.25, 135.91, 134.86, 132.85, 132.79,
131.09, 128.83, 128.61, 128.48, 127.31, 125.25, 58.36, 34.50,
30.36. FT-IR (neat): 3633, 2956, 1599, 1475, 1433, 1235, 1153,
1094, 1012, 818, 699 cm-1. MS: Calcd for C27H31ClOS: [M+H]+
439.1; Found, 439.1.
2,6-di-tert-butyl-4-[(3,5-dimethylphenyl)(p-tolylthio)methyl]
phenol (3ja): (211 mg, 95%). Pale yellow gummy. 1H NMR (400
MHz, Chloroform-d) δ 7.13 – 7.07 (m, 6H), 6.98 (d, J = 7.9 Hz,
2H), 6.85 (s, 1H), 5.28 (s, 1H), 5.09 (s, 1H), 2.28 (s, 6H), 2.27 (s,
3H), 1.38 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 152.84,
141.66, 137.86, 136.81, 135.63, 132.87, 132.22, 132.00, 129.43,
128.77, 126.26, 125.27, 58.77, 34.47, 30.39, 21.49, 21.16. FT-
IR (neat): 3636, 2954, 1598, 1491, 1433, 1360, 1231, 1152, 811,
736 cm-1. MS: Calcd for C30H38OS: [M+H]+ 447.2; Found, 447.2.
4-{[(4-bromophenyl)thio](phenyl)methyl}-2,6-di-tert-
butylphenol (3ae): (211 mg, 88%). Pale yellow solid. m.p. =
130 - 131 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.47 – 7.43 (m,
2H), 7.34 – 7.26 (m, 4H), 7.22 (s, 1H), 7.11 (s, 2H), 7.08 – 7.04
(m, 2H), 5.42 (s, 1H), 5.14 (s, 1H), 1.38 (s, 18H). 13C NMR (100
MHz, Chloroform-d) δ 153.13, 141.19, 135.91, 135.61, 132.83,
2,6-di-tert-butyl-4-[naphthalen-2-yl(p-tolylthio)methyl]phenol
(3ka): (217 mg, 93%). Yellow solid. m.p. = 134 - 135 oC. 1H
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
131.76, 131.04, 128.63, 128.47, 127.33, 125.24, 120.79, 58.15,
34.50, 30.36. FT-IR (neat): 3632, 2955, 1599, 1471, 1432, 1234,
1152, 1090, 1008, 804, 698 cm-1. MS: Calcd for C27H31BrOS:
[M+H]+ 483.1; Found, 483.1.
2,6-dimethyl-4-[phenyl(p-tolylthio)methyl]phenol (3ma): (158
mg, 95%). Pale gray gummy. H NMR (400 MHz, Chloroform-d)
1
δ 7.45 – 7.39 (m, 2H), 7.32 – 7.26 (m, 2H), 7.23 – 7.19 (m, 1H),
7.17 – 7.12 (m, 2H), 7.04 – 6.97 (m, 4H), 5.39 (s, 1H), 4.58 (s,
1H), 2.27 (s, 3H), 2.20 (s, 6H). 13C NMR (100 MHz, Chloroform-
d) δ 151.42, 141.80, 136.66, 132.82, 131.10, 129.57, 128.60,
128.54, 128.44, 127.09, 123.13, 57.53, 21.15, 16.11. FT-IR
(neat): 3586, 2960, 1468, 1283, 1199, 906, 802, 729 cm-1. MS:
Calcd for C22H22OS: [M+H]+ 335.1; Found, 335.1.
2,6-di-tert-butyl-4-[(naphthalen-1-ylthio)(phenyl)methyl]
phenol (3af): (100 mg, 88%). Pale yellow gummy. The reaction
was performed with 74 mg of 1a (0.25 mmol), dissolved in 2 mL
1
of CH2Cl2. H NMR (400 MHz, Chloroform-d) δ 8.50 (d, J = 8.3
Hz, 1H), 7.83 – 7.80 (m, 1H), 7.70 (d, J = 8.2 Hz, 1H), 7.56 –
7.47 (m, 4H), 7.38 (dd, J = 7.2, 1.2 Hz, 1H), 7.31 (t, J = 7.4 Hz,
2H), 7.26 – 7.20 (m, 2H), 7.06 (s, 2H), 5.49 (s, 1H), 5.09 (s, 1H),
1.34 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 152.91,
141.58, 135.62, 133.96, 133.23, 131.74, 131.61, 128.55, 128.48,
128.11, 127.15, 126.50, 126.10, 125.64, 125.54, 125.27, 58.28,
34.40, 30.32. FT-IR (neat): 3618, 2948, 1458, 1147, 912, 808,
733 cm-1. MS: Calcd for C31H34OS: [M+H]+ 455.2; Found, 455.2.
2,6-diisopropyl-4-[phenyl(p-tolylthio)methyl]phenol
(3na):
(178 mg, 91%). Yellow gummy. 1H NMR (400 MHz, Chloroform-
d) δ 7.46 – 7.42 (m, 2H), 7.34 – 7.25 (m, 2H), 7.24 – 7.19 (m,
1H), 7.17 – 7.13 (m, 2H), 7.05 (s, 2H), 6.99 (d, J = 7.8 Hz, 2H),
5.43 (s, 1H), 4.75 (s, 1H), 3.10 (p, J = 6.8 Hz, 2H), 2.27 (s, 3H),
1.22 (t, J = 6.5 Hz, 12H). 13C NMR (100 MHz, Chloroform-d) δ
149.11, 141.84, 136.86, 133.58, 133.01, 132.56, 131.94, 129.50,
128.47, 127.04, 123.80, 58.38, 27.41, 22.79, 21.17. FT-IR (neat):
3566, 2920, 1487, 1195, 1139, 907, 799, 729 cm-1. MS: Calcd
for C26H30OS: [M+H]+ 391.2; Found, 391.2.
2,6-di-tert-butyl-4-[(naphthalen-2-ylthio)(phenyl)methyl]
phenol (3ag): (103 mg, 91%). Yellow solid. m.p. = 132 - 133 oC.
The reaction was performed with 74 mg of 1a (0.25 mmol),
dissolved in 2 mL of CH2Cl2. 1H NMR (400 MHz, Chloroform-d) δ
7.76 – 7.72 (m, 1H), 7.67 – 7.59 (m, 3H), 7.55 – 7.51 (m, 2H),
7.41 (td, J = 6.3, 5.9, 3.3 Hz, 2H), 7.37 – 7.29 (m, 3H), 7.25 –
7.20 (m, 1H), 7.18 (s, 2H), 5.59 (s, 1H), 5.13 (s, 1H), 1.37 (s,
18H). 13C NMR (100 MHz, Chloroform-d) δ 153.03, 141.59,
135.85, 133.93, 133.71, 132.13, 131.47, 129.87, 128.97, 128.58,
128.53, 128.10, 127.70, 127.42, 127.21, 126.36, 125.91, 125.33,
58.07, 34.48, 30.37. FT-IR (neat): 3632, 2955, 1588, 1433, 1234,
1153, 907, 811, 731 cm-1. MS: Calcd for C31H34OS: [M+H]+
455.2; Found, 455.2.
General method for the 1,6-conjugate addition reaction of p-
QMs with -ketoacid (4)
p-QMs (0.25 mmol), (C4H12N2)2[BiCl6]Cl·H2O (10 mol%) and
-ketoacids (0.5 mmol) were added into a flask. To the flask,
dichloromethane (DCM, 2 mL) was added. The mixture was
stirred at room temperature for 3 hours (1,6-addition step). Then
triethylamine (4 μL, 0.027 mmol) was added into the reaction
system and stirred for another 4 hours (decarboxylation step).
After the completion of reaction, the residue was directly purified
by flash column chromatography with ethyl acetate and
petroleum ether (1:150) as eluents to afford pure product.
4-[(benzylthio)(phenyl)methyl]-2,6-di-tert-butylphenol (3ah):
(96 mg, 92%). Pale yellow solid. m.p. = 96 - 97 oC. The reaction
was performed with 74 mg of 1a (0.25 mmol), dissolved in 2 mL
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1,3-diphenylpropan-1-
one (5aa)： (98 mg, 95%). White solid. m.p. = 139 - 140 oC. H
1
1
of CH2Cl2; H NMR (400 MHz, Chloroform-d) δ 7.44 – 7.41 (m,
NMR (400 MHz, Chloroform-d) δ 7.91 – 7.88 (m, 2H), 7.56 –
7.51 (m, 1H), 7.45 – 7.39 (m, 2H), 7.31 – 7.26 (m, 4H), 7.20 –
7.14 (m, 1H), 7.02 (s, 2H), 5.04 (s, 1H), 4.73 (t, J = 7.4 Hz, 1H),
3.75 – 3.62 (m, 2H), 1.37 (s, 18H). FT-IR (neat): 3634, 2955,
1683, 1597, 1434, 1361, 1236, 1153, 739, 699 cm-1. MS (ESI):
Calcd for C29H34O2: [M-H]- 413.3; found, 413.3.
2H), 7.34 – 7.28 (m, 4H), 7.28 – 7.18 (m, 4H), 7.17 (s, 2H), 5.13
(s, 1H), 4.89 (s, 1H), 3.54 (s, 1H), 1.42 (s, 18H). FT-IR (neat):
3632, 2954, 1600, 1492, 1432, 1234, 1153, 697 cm-1. MS (ESI):
Calcd for C28H34OS: [M-H]- 417.2; Found, 417.0.
2,6-di-tert-butyl-4-{[(2-hydroxyethyl)thio](phenyl)methyl}
phenol (3ai): (90 mg, 96%). White solid. m.p. = 54 - 55 oC. The
reaction was performed with 74 mg of 1a (0.25 mmol), dissolved
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-(4-methoxyphenyl)-3-
phenylpropan-1-one (5ab): (109 mg, 98%). White solid. m.p. =
122 - 123 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.84 – 7.79 (m,
2H), 7.28 (d, J = 2.7 Hz, 4H), 7.24 (s, 1H), 7.22 (s, 1H), 7.19 –
7.14 (m, 1H), 7.03 (s, 2H), 5.04 (s, 1H), 4.73 (t, J = 7.4 Hz, 1H),
3.73 – 3.60 (m, 2H), 2.40 (s, 3H), 1.38 (s, 18H). FT-IR (neat):
3636, 2954, 1680, 1606, 1434, 1360, 1235, 1180, 737, 699 cm-1.
MS (ESI): Calcd for C30H36O3: [M-H]- 443.2; found, 443.0
1
in 2 mL of CH2Cl2. H NMR (400 MHz, Chloroform-d) δ 7.52 –
7.47 (m, 2H), 7.38 – 7.34 (m, 2H), 7.25 (s, 3H), 5.19 (s, 1H),
5.16 (s, 1H), 3.67 (t, J = 6.2 Hz, 2H), 2.64 (t, J = 6.0 Hz, 2H),
2.15 (s, 1H), 1.45 (s, 18H). FT-IR (neat): 3633, 2957, 1433,
1264, 1235, 1055, 890, 733 cm-1. MS (ESI): Calcd for C23H32O2S:
[M-H]- 371.2; Found: 371.0.
S-[(3,5-di-tert-butyl-4-hydroxyphenyl)(phenyl)methyl]
ethanethioate (3aj): (169 mg, 91%). Yellow gummy. 1H NMR
(400 MHz, Chloroform-d) δ 7.42 – 7.38 (m, 2H), 7.35 – 7.30 (m,
2H), 7.29 – 7.20 (m, 1H), 7.14 (s, 2H), 5.92 (s, 1H), 5.20 (s, 1H),
2.36 (s, 3H), 1.43 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ
194.29, 153.05, 142.02, 135.98, 131.28, 128.52, 128.35, 127.12,
125.21, 52.24, 34.51, 30.37. FT-IR (neat): 3637, 2957, 1683,
1433, 1235, 905, 726, 632 cm-1. MS: Calcd for C23H30O2S:
[M+H]+ 371.1; Found, 371.1.
1-(4-chlorophenyl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-
phenylpropan-1-one (5ae): (97 mg, 87%). White solid. m.p. =
o
1
143 - 144 C. H NMR (400 MHz, Chloroform-d) δ 7.82 (d, J =
8.6 Hz, 2H), 7.39 (d, J = 8.6 Hz, 2H), 7.27 (d, J = 4.8 Hz, 4H),
7.21 – 7.14 (m, 1H), 7.01 (s, 2H), 5.05 (s, 1H), 4.70 (t, J = 7.4 Hz,
1H), 3.71 – 3.58 (m, 2H), 1.37 (s, 18H). FT-IR (neat): 3636,
2955, 1683, 1588, 1434, 1361, 1235, 1091, 738, 699 cm-1. MS
(ESI): Calcd for C29H33ClO2: [M-H]- 447.2; found, 447.2.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201901732
European Journal of Organic Chemistry
COMMUNICATION
4-(3,5-di-tert-butyl-4-hydroxyphenyl)-4-phenylbutan-2-one
(5af): (43 mg, 49%). Yellow gummy. 1H NMR (400 MHz,
Chloroform-d) δ 7.30 – 7.27 (m, 2H), 7.26 – 7.22 (m, 2H), 7.20 –
7.15 (m, 1H), 7.01 (s, 2H), 5.06 (s, 1H), 4.52 – 4.46 (m, 1H),
3.22 – 3.06 (m, 2H), 2.07 (s, 3H), 1.40 (s, 18H). 13C NMR (100
MHz, Chloroform-d) δ 207.52, 152.34, 144.50, 135.92, 134.54,
128.62, 127.83, 126.38, 124.31, 50.63, 46.44, 34.52, 30.80,
30.45. FT-IR (neat): 3638, 2955, 1715, 1435, 1361, 1235, 1157,
700 cm-1. MS (ESI): Calcd for C24H32O2: [M-H]- 351.2; found,
351.1.
1264, 737, 704 cm-1. MS (ESI): Calcd for C27H32O2S: [M-H]-
419.2; found, 419.2.
General method for the 1,6-conjugate addition reaction of p-
QMs with naphthalen-2-ol (6)
p-QMs (0.25 mmol), (C4H12N2)2[BiCl6]Cl·H2O (10 mol%) and
naphthalen-2-ol (0.5 mmol) were placed into a flask. To the flask,
dichloromethane (DCM, 2 mL) was added. Then the mixture was
stirred at room temperature, until p-QMs was completely
consumed as indicated by TLC analysis. After the completion of
reaction, the residue was directly purified by flash column
chromatography with ethyl acetate and petroleum ether (1:100)
as eluents to afford pure product.
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenyl-3-(p-tolyl)
propan-1-one (5ba): (100 mg, 93%). Pale yellow solid. m.p. =
106 - 107 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.93 – 7.87 (m,
2H), 7.56 – 7.50 (m, 1H), 7.44 – 7.40 (m, 2H), 7.17 (d, J = 8.1
Hz, 2H), 7.10 – 7.06 (m, 2H), 7.03 (s, 2H), 5.03 (s, 1H), 4.69 (t, J
= 7.4 Hz, 1H), 3.72 – 3.61 (m, 2H), 2.29 (s, 3H), 1.37 (s, 18H).
FT-IR (neat): 3636, 2954, 1683, 1597, 1512, 1434, 1360, 1235,
811, 750, 689 cm-1. MS (ESI): Calcd for C20H36O2: [M-H]- 427.2;
found, 427.1.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(phenyl)methyl]
naphthalen-2-ol (7a): (202 mg, 92%). Pale yellow solid. The
reaction was performed with 147 mg of 1a (0.5 mmol), dissolved
in 2 mL of CH2Cl2. 1H NMR (400 MHz, Chloroform-d) δ 8.03 (d, J
= 14.0 Hz, 1H), 7.79 (d, J = 11.4 Hz, 1H), 7.73 (d, J = 11.4 Hz,
1H), 7.43 (s, 1H), 7.32 (d, J = 10.1 Hz, 1H), 7.28 (s, 3H), 7.23 (d,
J = 1.6 Hz, 2H), 7.08 (d, J = 7.0 Hz, 1H), 7.01 (s, 2H), 6.29 (s,
1H), 5.40 (s, 1H), 5.21 (s, 1H), 1.33 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 153.24, 153.18, 142.22, 136.87, 133.62, 131.92,
129.68, 129.58, 129.58, 129.14, 129.02, 128.80, 127.04, 126.80,
125.79, 123.17, 123.01, 120.38, 120.08, 48.73, 34.57, 30.34.
FT-IR (neat): 3633, 3459, 2957, 1601, 1434, 1209, 1141, 906,
730, 649 cm-1. MS (ESI): Calcd for C31H34O2: [M-H]- 437.2; found,
437.2.
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-(4-nitrophenyl)-1-
phenylpropan-1-one (5da): (54 mg, 47%). Pale yellow solid.
m.p. = 151 - 152 oC. 1H NMR (400 MHz, Chloroform-d) δ 8.18 –
8.09 (m, 2H), 7.95 – 7.88 (m, 2H), 7.60 – 7.54 (m, 1H), 7.50 –
7.38 (m, 4H), 6.99 (s, 2H), 5.12 (s, 1H), 4.87 – 4.78 (m, 1H),
3.82 – 3.63 (m, 2H), 1.38 (s, 18H). FT-IR (neat): 3632, 2955,
1683, 1596, 1518, 1434, 1343, 1236, 856, 752, 689 cm-1. MS
(ESI): Calcd for C29H33NO4: [M-H]- 458.2; found, 458.0.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(p-tolyl)methyl]
naphthalen-2-ol (7b): (94 mg, 83%). Pale yellow solid. 1H NMR
(400 MHz, Chloroform-d) δ 8.08 – 8.02 (m, 1H), 7.81 – 7.77 (m,
1H), 7.73 (d, J = 8.8 Hz, 1H), 7.46 – 7.41 (m, 1H), 7.35 – 7.30
(m, 1H), 7.14 (d, J = 1.4 Hz, 4H), 7.10 – 7.04 (m, 3H), 6.27 (s,
1H), 5.44 (s, 1H), 5.21 (s, 1H), 2.33 (s, 3H), 1.35 (s, 18H). 13C
NMR (100 MHz, Chloroform-d) δ 153.16, 153.08, 139.22, 136.75,
136.59, 133.61, 131.92, 129.77, 129.65, 129.47, 128.94, 128.77,
126.77, 125.77, 123.12, 123.00, 120.67, 120.05, 48.30, 34.54,
30.36, 21.20. FT-IR (neat): 3632, 3462, 2956, 1601, 1434, 1264,
1141, 812, 739 cm-1. MS (ESI): Calcd for C32H36O2: [M-H]- 451.2;
found, 451.2.
3-(4-chlorophenyl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-
phenylpropan-1-one (5ha): (106 mg, 95%) White solid. 1H
NMR (400 MHz, Chloroform-d) δ 7.92 – 7.87 (m, 2H), 7.57 –
7.52 (m, 1H), 7.46 – 7.41 (m, 2H), 7.25 – 7.18 (m, 4H), 6.98 (s,
2H), 5.07 (s, 1H), 4.73 – 4.67 (m, 1H), 3.72 – 3.59 (m, 2H), 1.37
(s, 18H). FT-IR (neat): 3636, 2954, 1683, 1588, 1361, 1235, 738,
704 cm-1. MS (ESI): Calcd for C29H33ClO2: [M-H]- 447.2; found,
447.0.
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-(naphthalen-1-yl)-1-
phenylpropan-1-one (5ka): (111 mg, 96%) White solid. m.p. =
o
1
151 - 152 C. H NMR (400 MHz, Chloroform-d) δ 8.30 (d, J =
8.3 Hz, 1H), 7.96 – 7.83 (m, 3H), 7.74 (d, J = 8.0 Hz, 1H), 7.56 –
7.36 (m, 7H), 7.09 (s, 2H), 5.62 (t, J = 7.2 Hz, 1H), 5.03 (s, 1H),
3.95 – 3.85 (m, 1H), 3.80 – 3.70 (m, 1H), 1.35 (s, 18H). 13C NMR
(100 MHz, Chloroform-d) δ 199.02, 152.25, 140.68, 137.55,
135.81, 134.25, 134.08, 133.04, 131.82, 128.90, 128.64, 128.19,
127.14, 126.15, 125.55, 125.38, 124.70, 124.29, 124.08, 45.60,
41.85, 34.44, 30.40. FT-IR (neat): 3632, 2956, 1682, 1597, 1434,
1360, 1234, 1153, 1021, 734, 689 cm-1. MS (ESI): Calcd for
C33H36O2 [M-H]- 463.2; found, 462.9.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(4-methoxyphenyl)
methyl]naphthalen-2-ol (7c): (101 mg, 86%). Yellow gummy.
1H NMR (400 MHz, Chloroform-d) δ 8.05 (t, J = 7.1 Hz, 1H), 7.81
(d, J = 9.2 Hz, 1H), 7.75 (s, 1H), 7.45 (d, J = 6.0 Hz, 1H), 7.34 (d,
J = 8.7 Hz, 1H), 7.20 (s, 2H), 7.11 – 7.08 (m, 1H), 7.06 (s, 2H),
6.88 (s, 2H), 6.27 (s, 1H), 5.47 (s, 1H), 5.22 (s, 1H), 3.79 (s, 3H),
1.36 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 158.54,
153.14, 153.11, 136.82, 134.14, 133.56, 132.18, 130.14, 129.66,
129.47, 128.79, 126.76, 125.70, 123.13, 122.98, 120.64, 120.07,
114.41, 55.36, 47.87, 34.55, 30.36. FT-IR (neat): 3632, 3456,
2956, 1601, 1434, 1247, 1141, 1033, 806, 729 cm-1. MS (ESI):
Calcd for C32H36O3: [M-H]- 467.2; found, 467.2.
3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenyl-3-(thiophen-2-
yl)propan-1-one (5la): (98 mg, 93%). Pale yellow gummy. 1H
NMR (400 MHz, Chloroform-d) δ 7.95 – 7.87 (m, 2H), 7.57 –
7.51 (m, 1H), 7.47 – 7.40 (m, 2H), 7.12 (d, J = 5.3 Hz, 3H), 6.91
– 6.82 (m, 2H), 5.09 (s, 1H), 5.01 – 4.95 (m, 1H), 3.80 – 3.73 (m,
1H), 3.66 – 3.58 (m, 1H), 1.40 (s, 18H). 13C NMR (100 MHz,
CDCl3) δ 198.37, 152.59, 149.08, 137.39, 135.94, 134.43,
133.10, 128.65, 128.22, 126.67, 124.39, 124.29, 123.62, 47.19,
42.16, 34.49, 30.43. FT-IR (neat): 3355, 2919, 1688, 1470, 1434,
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(4-nitrophenyl)methyl]
naphthalen-2-ol (7d): (224 mg, 93%). Pale yellow solid. m.p. =
190 - 192 oC. The reaction was performed with 164 mg of 1d
(0.5 mmol), dissolved in 2 mL of CH2Cl2. 1H NMR (400 MHz,
Chloroform-d) δ 8.17 (d, J = 2.0 Hz, 1H), 8.15 (d, J = 2.0 Hz, 1H),
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7.87 (d, J = 8.6 Hz, 1H), 7.82 – 7.79 (m, 1H), 7.76 (d, J = 8.8 Hz,
1H), 7.46 (d, J = 0.6 Hz, 1H), 7.43 (d, J = 0.8 Hz, 1H), 7.42 (d, J
= 1.6 Hz, 1H), 7.36 – 7.31 (m, 1H), 7.08 (d, J = 8.8 Hz, 1H), 6.98
(d, J = 0.7 Hz, 2H), 6.40 (s, 1H), 5.33 (s, 1H), 5.28 (s, 1H), 1.33
(s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 153.52, 153.03,
150.66, 146.79, 137.27, 133.27, 130.69, 130.20, 130.10, 129.84,
129.05, 127.06, 125.69, 123.97, 123.49, 122.82, 119.91, 119.24,
48.51, 34.63, 30.30. FT-IR (neat): 3625, 3458, 2958, 1601, 1516,
1434, 1344, 1210, 1153, 810, 740 cm-1. MS (ESI): Calcd for
C31H33NO4: [M-H]- 482.2; found, 482.2.
18H). 13C NMR (100 MHz, Chloroform-d) δ 153.80, 153.46,
139.43, 137.23, 134.46, 133.63, 130.74, 130.25, 129.87, 129.83,
129.65, 128.77, 128.48, 127.51, 127.08, 125.29, 123.32, 122.88,
120.11, 119.53, 46.11, 34.57, 30.31. FT-IR (neat): 3632, 3456,
2958, 1621, 1518, 1434, 1211, 1142, 814, 744 cm-1. MS (ESI):
Calcd for C31H33ClO2: [M-H]- 471.2; found, 471.2.
1-[(2-bromophenyl)(3,5-di-tert-butyl-4-hydroxyphenyl)methyl]
naphthalen-2-ol (7I): (120 mg, 93%). Pale yellow solid. m.p. =
o
1
134 - 135 C. H NMR (400 MHz, Chloroform-d) δ 7.89 (d, J =
7.2 Hz, 1H), 7.78 (s, 1H), 7.73 (d, J = 8.2 Hz, 1H), 7.66 (s, 1H),
7.44 (s, 1H), 7.33 (d, J = 8.1 Hz, 1H), 7.19 (s, 1H), 7.15 – 7.09
(m, 2H), 7.07 (s, 1H), 6.89 (s, 2H), 6.54 (s, 1H), 5.50 (s, 1H),
5.23 (s, 1H), 1.31 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ
153.77, 153.45, 141.07, 137.23, 133.68, 133.29, 130.88, 130.19,
129.86, 129.66, 128.76, 128.72, 128.15, 127.09, 125.44, 125.42,
123.32, 123.03, 120.11, 48.90, 34.58, 30.32. FT-IR (neat): 3627,
3451, 2956, 1601, 1518, 1433, 1211, 1141, 1023, 814, 741 cm-1.
MS (ESI): Calcd for C31H33BrO2: [M-H]- 515.2; found, 515.2
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(4-fluorophenyl)methyl]
naphthalen-2-ol (7g): (215 mg, 94%). Pale yellow solid. m.p. =
163 - 164 oC. The reaction was performed with 156 mg of 1g
(0.5 mmol), dissolved in 2 mL of CH2Cl2. 1H NMR (400 MHz,
Chloroform-d) δ 7.98 (d, J = 8.5 Hz, 1H), 7.82 – 7.78 (m, 1H),
7.74 (d, J = 8.9 Hz, 1H), 7.46 – 7.41 (m, 1H), 7.36 – 7.31 (m,
1H), 7.26 – 7.20 (m, 2H), 7.07 (d, J = 8.9 Hz, 1H), 7.03 – 6.98
(m, 4H), 6.28 (s, 1H), 5.39 (s, 1H), 5.24 (s, 1H), 1.34 (s, 18H).
13C NMR (100 MHz, Chloroform-d) δ 163.03, 160.59, 153.31,
153.16, 137.69 (137.66), 137.08, 133.46, 131.94, 130.78,
130.70, 129.73, 128.88, 126.86, 125.64, 123.26, 122.89, 120.14,
120.10, 115.88, 115.67, 47.99, 34.59, 30.33. FT-IR (neat): 3632,
3457, 2958, 1602, 1505, 1434, 1232, 1157, 815, 741 cm-1. MS
(ESI): Calcd for C31H33FO2: [M-H]- 456.3; found, 455.5.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(2-hydroxyphenyl)
methyl]naphthalen-2-ol (7j): (108 mg, 95%). Pale yellow solid.
m.p. = 190 - 191 oC. 1H NMR (400 MHz, Chloroform-d) δ 8.01 (d,
J = 8.6 Hz, 1H), 7.80 – 7.71 (m, 2H), 7.45 – 7.40 (m, 1H), 7.35 –
7.30 (m, 1H), 7.19 – 7.14 (m, 1H), 7.08 – 7.00 (m, 4H), 6.89 –
6.83 (m, 2H), 6.46 (s, 1H), 5.58 (s, 1H), 5.22 (s, 1H), 5.02 (s, 1H),
1-[(4-chlorophenyl)(3,5-di-tert-butyl-4-hydroxyphenyl)methyl] 1.33 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 153.67,
naphthalen-2-ol (7h): (193 mg, 82%). Pale yellow solid. m.p. =
156 - 157 oC. The reaction was performed with 164 mg of 1h
(0.5 mmol), dissolved in 2 mL of CH2Cl2. 1H NMR (400 MHz,
Chloroform-d) δ 7.95 (t, J = 6.7 Hz, 1H), 7.78 (s, 1H), 7.75 –
7.71 (m, 1H), 7.45 – 7.40 (m, 1H), 7.33 (d, J = 6.6 Hz, 1H), 7.30
– 7.26 (m, 2H), 7.20 (d, J = 10.5 Hz, 2H), 7.07 (d, J = 9.1 Hz,
1H), 6.99 (s, 2H), 6.26 (s, 1H), 5.36 (s, 1H), 5.24 (s, 1H), 1.33 (s,
18H). 13C NMR (100 MHz, Chloroform-d) δ 153.16, 140.73,
137.09, 133.42, 132.67, 129.81, 129.72, 129.07, 128.89, 126.91,
125.65, 123.30, 122.86, 120.07, 119.85, 48.11, 34.60, 30.32.
FT-IR (neat): 3632, 3459, 2959, 1488, 1434, 1209, 1142, 1014,
811, 741 cm-1. MS (ESI): Calcd for C31H33ClO2: [M-H]- 471.2;
found, 471.3.
153.56, 153.38, 137.08, 133.46, 130.32, 130.09, 129.81, 129.78,
128.82, 128.62, 128.26, 126.95, 125.41, 123.33, 123.08, 121.66,
119.91, 116.27, 42.91, 34.58, 30.33. FT-IR (neat): 3632, 3447,
2957, 1601, 1434, 1398, 1317, 1264, 1142, 810, 738 cm-1. MS
(ESI): Calcd for C31H34O3: [M-H]- 453.3; found, 453.3.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(naphthalen-1-yl)
methyl]naphthalen-2-ol (7k): (108 mg, 89%). Pale yellow solid.
m.p. = 178 - 179 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.95 (s,
1H), 7.91 – 7.86 (m, 2H), 7.80 (d, J = 11.3 Hz, 2H), 7.73 (s, 1H),
7.46 (s, 1H), 7.41 – 7.30 (m, 4H), 7.14 (d, J = 7.5 Hz, 1H), 7.00
(s, 3H), 6.88 (s, 1H), 5.59 (s, 1H), 5.18 (s, 1H), 1.28 (s, 18H). 13
C
NMR (100 MHz, Chloroform-d) δ 154.14, 153.17, 138.49, 136.87,
134.23, 133.42, 131.99, 131.49, 129.73, 129.61, 129.05, 128.85,
1-[(4-bromophenyl)(3,5-di-tert-butyl-4-hydroxyphenyl)methyl] 128.30, 127.02, 126.98, 126.58, 125.99, 125.94, 125.85, 124.21,
naphthalen-2-ol (7i): (101 mg, 78%). Pale yellow solid. m.p. =
123.18, 122.85, 119.99, 46.04, 34.51, 30.34. FT-IR (neat): 3627,
3461, 2956, 1621, 1518, 1434, 1209, 1141, 788, 739 cm-1. MS
(ESI): Calcd for C35H36O2: [M-H]- 487.3; found, 487.3.
o
1
134 - 135 C. H NMR (400 MHz, Chloroform-d) δ 7.93 (s, 1H),
7.81 – 7.77 (m, 1H), 7.73 (d, J = 8.8 Hz, 1H), 7.47 – 7.39 (m,
3H), 7.36 – 7.30 (m, 1H), 7.17 – 7.12 (m, 2H), 7.06 (d, J = 8.8
Hz, 1H), 6.99 (d, J = 0.8 Hz, 2H), 6.24 (s, 1H), 5.35 (s, 1H), 5.24
(s, 1H), 1.33 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ
153.33, 153.12, 141.34, 137.06, 133.40, 131.99, 130.95, 129.81,
129.71, 128.89, 126.89, 125.66, 123.30, 122.88, 120.02, 119.82,
48.14, 34.58, 30.31. FT-IR (neat): 3632, 3454, 2957, 1601, 1433,
1208, 1142, 1010, 904, 727, 649 cm-1. MS (ESI): Calcd for
C31H33BrO2: [M-H]- 515.1; found, 515.4.
1-[(3,5-di-tert-butyl-4-hydroxyphenyl)(thiophen-2-yl)methyl]
naphthalen-2-ol (7l): (93 mg, 83%). Yellow gummy. 1H NMR
(400 MHz, Chloroform-d) δ 8.06 (d, J = 13.3 Hz, 1H), 7.80 (s,
1H), 7.75 (d, J = 11.4 Hz, 1H), 7.47 (d, J = 7.1 Hz, 1H), 7.35 (d,
J = 13.3 Hz, 1H), 7.26 (s, 1H), 7.17 (s, 2H), 7.11 (d, J = 10.9 Hz,
1H), 6.95 (s, 1H), 6.83 (s, 1H), 6.49 (s, 1H), 5.59 (s, 1H), 5.22 (s,
1H), 1.37 (s, 18H). 13C NMR (100 MHz, Chloroform-d) δ 153.32,
153.10, 146.78, 136.69, 133.13, 131.52, 129.84, 129.61, 129.61,
1-[(2-chlorophenyl)(3,5-di-tert-butyl-4-hydroxyphenyl)methyl] 127.02, 126.92, 126.80, 125.66, 125.19, 123.28, 122.70, 120.49,
naphthalen-2-ol (7H): (116 mg, 98%). Pale yellow solid. m.p. = 120.02, 43.74, 34.38, 30.52. FT-IR (neat): 3632, 3460, 2957,
137 - 138 oC. 1H NMR (400 MHz, Chloroform-d) δ 7.93 – 7.89 (m, 1601, 1434, 1210, 1153, 906, 730, 649 cm-1. MS (ESI): Calcd for
1H), 7.80 – 7.72 (m, 2H), 7.46 (d, J = 7.3 Hz, 2H), 7.35 – 7.30
(m, 1H), 7.22 – 7.18 (m, 1H), 7.15 (s, 2H), 7.07 (d, J = 8.1 Hz,
1H), 6.91 (s, 2H), 6.60 (s, 1H), 5.50 (s, 1H), 5.24 (s, 1H), 1.32 (s,
C29H32O2S: [M-H]- 443.2; found, 443.3.
tert-butyl-3-[(3,5-di-tert-butyl-4-hydroxyphenyl)(2-
hydroxynaphthalen-1-yl)methyl]-1H-indole-1-carboxylate
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10.1002/ejoc.201901732
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COMMUNICATION
(7m): (65 mg, 45%). Yellow solid. m.p. = 172 - 173 oC. 1H NMR
(400 MHz, Chloroform-d) δ 8.12 (d, J = 8.6 Hz, 2H), 7.84 (d, J =
9.4 Hz, 1H), 7.75 (d, J = 8.9 Hz, 1H), 7.50 – 7.46 (m, 1H), 7.39 –
7.34 (m, 1H), 7.30 (t, J = 8.0 Hz, 1H), 7.19 (d, J = 1.5 Hz, 2H),
7.16 – 7.04 (m, 4H), 6.37 (s, 1H), 5.97 – 5.87 (m, 1H), 5.19 (s,
1H), 1.64 (s, 9H), 1.35 (s, 18H). 13C NMR (100 MHz,
Chloroform-d) δ 153.57, 152.96, 136.45, 130.18, 129.90, 129.60,
129.49, 128.81, 126.75, 125.22, 125.17, 124.91, 123.06, 122.66,
122.60, 120.00, 119.57, 118.51, 115.33, 83.87, 40.17, 34.42,
30.28, 28.18. FT-IR (neat): 3632, 3461, 2958, 1732, 1451, 1370,
1256, 1154, 1081, 821, 745 cm-1. MS (ESI): Calcd for C38H43NO4:
[M-H]- 576.3; found, 576.3.
[7] T. Zhou, S. Li, B. Huang, C. Li, Y. Zhao, J. Chen, A. Chen, Y. Xiao, L. Liu,
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General procedure for the recovery of the [Bi] catalyst
p-QMs (0.5 mmol), (C4H12N2)2[BiCl6]Cl·H2O (10 mol%) and
p-methylthiophenol (2a) (1 mmol) were added into a flask. To
the flask, dichloromethane (DCM, 2 mL) was added. Then the
mixture was stirred at room temperature, until p-QMs was
completely consumed as indicated by TLC analysis. After the
completion of reaction, the [Bi] catalyst was directly recovered
by filtration and washed with DCM. Then, the recovered [Bi]
catalyst could be reused without further process.
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Cheng, ACS Omega. 2018, 3, 1409-1415. (b) A. S. Jadhav, R. V. Anand,
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Acknowledgments
[15] H. Lu, J. Zhou, H. Cheng, L. Sun, F. Yang, R. Wu, Y. Gao, Z. Luo,
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[16] X. Zhang, X. Gu, Y. Gao, S. Nie, H. Lu, Appl. Organometal. Chem. 2017,
31, 1-10.
We thank the National Natural Science Foundation of China
(21901087), Natural Science Foundation of Jiangsu Province
(BK20190951), Jiangsu Education Department (19KJB150008)
and Qing Lan Project of Jiangsu Province.
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Keywords: para-quinone methides • 1,6-conjugate addition
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(c) Y. Cheng, Z. Fang, Y. Jia, Z. Lu, W. Li, P. Li, RSC Adv. 2019, 9,
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reaction • bismuth complex • triarylmethane derivatives
•
diarylmethane derivatives
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Entry for the Table of Contents (Please choose one layout)
COMMUNICATION
An efficient method for the 1,6-
conjugate addition of para-quinone
methides with readily available
nucleophiles was developed. This
protocol provides straightforward
access to a class of diaryl and
triarylmethane derivatives with good
to excellent yields in the presence of
(C4H12N2)2[BiCl6]Cl·H2O. Moreover,
this bismuth complex can be
recycled for several times.
Key Topic*
Xianghao Liang,† Haiyan Xu,†* Hanlin
Li, Lizhuang Chen and Hongfei Lu*
Page No. – Page No.
Recyclable
catalyzed 1,6-conjugate addition of
various nucleophiles to para-
quinone
access to unsymmetrical diaryl-
and triarylmethanes
bismuth
complex
methides:
expedient
*Recyclable catalyst / diaryl- and
triarylmethanes synthesis
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