The construction of C(sp3)–O bond via copper porphyrin catalyzed cross-dehydrogenative coupling reaction: Substituent and electronic effect of the catalysts

Article abstract of DOI:10.1080/00397911.2021.1919900

The push-pull electronic and steric effect of copper porphyrin catalysts on the cross-dehydrogenative coupling (CDC) reaction between the hydroxyl group of phenol substrates and C(sp³)-H bond have been investigated. Results showed that copper porphyrin bearing electron-withdrawing, bulky steric hindrance or heteroatom of pyridyl groups could increase the catalytic activity in the reaction. 5,10,15,20-(tetrakis(4-pyridyl)porphyrin)copper (CuTPyP) was found the best among all tested catalysts. Phenol substrates bearing various functional groups afforded moderate to excellent yields (99%). Significantly, as compared to other tested copper porphyrins, CuTPyP not only exhibited remarkable higher activity but also could shorten the reaction time from 12 to 6 h.

Full text of DOI:10.1080/00397911.2021.1919900

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
The construction of C(sp3)–O bond via copper
porphyrin catalyzed cross-dehydrogenative
coupling reaction: Substituent and electronic
effect of the catalysts
Feng-Hua Wang, Zheng-Yan Liu, Shuang Yang, Lei Shi, Dong-Zi Lin, Hai-Yang
Liu & Gao-Qing Yuan
To cite this article: Feng-Hua Wang, Zheng-Yan Liu, Shuang Yang, Lei Shi, Dong-Zi Lin, Hai-
Yang Liu & Gao-Qing Yuan (2021) The construction of C(sp3)–O bond via copper porphyrin
catalyzed cross-dehydrogenative coupling reaction: Substituent and electronic effect of the
catalysts, Synthetic Communications, 51:13, 2053-2062, DOI: 10.1080/00397911.2021.1919900
To link to this article: https://doi.org/10.1080/00397911.2021.1919900
Published online: 13 May 2021.
Article views: 120
View supplementary material
Submit your article to this journal
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=lsyc20

R
SYNTHETIC COMMUNICATIONSV
2021, VOL. 51, NO. 13, 2053–2062
https://doi.org/10.1080/00397911.2021.1919900
The construction of C(sp3)–O bond via copper porphyrin
catalyzed cross-dehydrogenative coupling reaction:
Substituent and electronic effect of the catalysts
Feng-Hua Wanga, Zheng-Yan Liua, Shuang Yanga, Lei Shib, Dong-Zi Linc,
Hai-Yang Liua, and Gao-Qing Yuana
aDepartment of Chemistry, Key Laboratory of Functional Molecular Engineering of Guangdong Province,
b
South China University of Technology, Guangzhou, China; Department of Chemistry, Guangdong
c
University of Education, Guangzhou, China; Department of Laboratory Medicine, Foshan Forth People’s
Hospital, Foshan, China
ABSTRACT
ARTICLE HISTORY
Received 23 December 2020
The push-pull electronic and steric effect of copper porphyrin cata-
lysts on the cross-dehydrogenative coupling (CDC) reaction between
the hydroxyl group of phenol substrates and C(sp3)-H bond have
been investigated. Results showed that copper porphyrin bearing
electron-withdrawing, bulky steric hindrance or heteroatom of pyr-
idyl groups could increase the catalytic activity in the reaction.
5,10,15,20-(tetrakis(4-pyridyl)porphyrin)copper (CuTPyP) was found
the best among all tested catalysts. Phenol substrates bearing vari-
ous functional groups afforded moderate to excellent yields (99%).
Significantly, as compared to other tested copper porphyrins,
CuTPyP not only exhibited remarkable higher activity but also could
shorten the reaction time from 12 to 6 h.
KEYWORDS
Copper porphyrin; cross-
dehydrogenative coupling
reaction; electronic effect;
spatial effect
GRAPHICAL ABSTRACT
1. Introduction
To build C–X (X¼C, O, N) bonds efficiently, straightforwardly, and highly atom-
economically, oxidative coupling reactions have been explored extensively.[1,2] The
most attractive aspect of the oxidation coupling reaction is that it does not require pre-
functionalization of substrates. Cross-dehydrogenative coupling (CDC) reaction as one
CONTACT Hai-Yang Liu
chhyliu@scut.edu.cn; Gao-Qing Yuan
gqyuan@scut.edu.cn
Department of Chemistry,
Key Laboratory of Functional Molecular Engineering of Guangdong Province, South China University of Technology,
Guangzhou, China; Lei Shi
Guangzhou, China
shil@gdei.edu.cn
Department of Chemistry, Guangdong University of Education,
Supplemental data for this article can be accessed on the publisher’s website.
ß 2021 Taylor & Francis Group, LLC

2054
F.-H. WANG ET AL.
Scheme 1. Reported CDC reaction of phenol derivatives with ethers.
of the oxidative coupling reactions has intrigued researchers for a long time.[3] The
C–O bond formation is of importance for the synthesis of a lot of natural products.[4]
However, the construction of C–O bond via CDC reaction is still of considerable chal-
lenge.[5] Recently, the carbamate C(sp2)–O bond has been constructed successfully by
using CDC reaction between amides and phenols with substituents bearing directing
groups capable of coordinating with the central metal atom of the catalyst.[6] The con-
struction of C(sp3)–O bond via CDC phenol with cyclic ether has also been achieved by
[7a]
[7b–d]
Cu(OAc)2
(Scheme 1, a) and Cu–MOFs
(Scheme 1, b) catalysts. These reports
also showed phenol substrates must have ortho-position directing groups to facilitate
the CDC reaction.[6,7]
Metalloporphyrins have a wide range of applications in electrochemistry,[8a] medicinal
chemistry,[8b] and catalysis.[8c] They are effective catalysts for oxidation,[9a] cyclopropa-
nation[9b] and asymmetric synthesis reactions.[9c] Study on the metalloporphyrin as cat-
alysts in CDC reaction is a new topic of contemporary porphyrin chemistry. In 2013,
Che reported palladium porphyrin PdF20TPP catalyzed CDC reaction between tertiary
amines and various nucleophiles (nitromethane, diethyl phosphite, dimethyl malonate
and acetone) to give a-functionalized amines with excellent yield under light condi-
tions.[10] We also found that C(sp3)–O bonds could be constructed by coupling benzoic
acid derivatives with 1,4-dioxane or cyclohexene by using copper or iron tetrakis(ethox-
ycarbonyl) porphyrin (TECP) as catalysts.[11] The CDC reaction between phenol deriva-
tives and cyclic ethers has also been achieved by using CuTECP as the catalyst (Scheme
1, c), although the phenols bearing electron-donating group (EDG) were found not
work.[12] It is well known that the manganese porphyrins bearing the electron-with-
drawing group (EWG) have enhanced activity in catalytic oxidation reactions.[13] How
about the effect of peripheral substituents on the activity of metalloporphyrin in CDC
reactions? Bearing this in mind and going on our continuous effort in developing

R
SYNTHETIC COMMUNICATIONSV
2055
Scheme 2. The molecular structure of copper porphyrin catalysts.
metalloporphyrin catalysts for CDC reactions, we herein wish to report the CDC cata-
lytic activity of five copper porphyrins (Scheme 2) by using phenols and cyclic ethers as
substrates for the construction of C(sp3)–O bond.
2. Result and discussion
The CDC reaction of methyl 4-hydroxybenzoate 1 and 1,4-dioxane a was used to
explore the effect of peripheral substituents on the activity of metalloporphyrin
(Table 1, entries 1–5). On the one hand, we have investigated the electronic effect of
the catalyst on the reaction by using CuTPP and CuF20TPP, they have similar structure
but different electronic properties, and found that CuF20TPP bearing electron-withdraw-
ing petafluorophenyl groups gave a higher yield (Table 1, entries 1–2), suggesting that
the copper porphyrin periphery with electron-withdrawing substituents could enhance
the catalytic activity in this reaction. On the other hand, the steric effect was examined
by using CuTtBP and CuTnPP. The results showed that CuTtBP[14] with a bulky steric
hindrance and distortion spatial structure offered a higher yield than CuTnPP (Table 1,
entries 4–5). This demonstrated that the steric resistance of spatial structure could pro-
mote the performance of catalysts in the reaction. Besides, we found that CuTPyP pro-
vided a higher yield (Table 1, entry 3), probably due to the H-bonding of the hydroxyl
group on phenol with heteroatoms of CuTPyP improved catalytic activity signifi-
cantly.[15] Hence CuTPyP was selected to be an efficient catalyst for this reaction.
Various oxidants such as I2, TBHP (70% in H2O), PhI(OAc)2, Oxone, BPO, DDQ and
O2 were tested (Table 1, entries 8–14), and the results showed that DTBP was the most
suitable for the reaction. When the amount of DTBP increased from 3.5 to 6.0 equiva-
lents, the yield of 1a increased up to 80% (Table 1, entry 15). Unexpectedly, the yield
remained 80% when the reaction time was reduced to 6 h (Table 1, entries 19–22). Also,
1a could not be detected in the reaction without CuTPyP or DTBP (Table 1, entries
23–24). Other factors such as temperature and the catalyst loading were also tested
(Table 1, entries 6–7, 17–18).
With the optimal conditions in hand (Table 1, entry 20), we then explored the
CuTPyP-catalyzed CDC reaction with various phenols and 1,4-dioxane (Table 2).
Firstly, we screened the ortho-, meta-, and para- mono-substituted phenols with
–CO2Me, –CN or –CF3 in three different EWG groups (Table 2, 1–9). It’s shown that
these substrates were compatible with the optimal reaction conditions and could provide

2056
F.-H. WANG ET AL.
Table 1. Optimization of reaction conditionsa.
Entry
Catalyst (mol%)
Oxidant (equiv.)
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
CuTPP (3)
CuF20TPP (3)
CuTPyP (3)
CuTnPP (3)
CuTtBP (3)
CuTPyP (6)
CuTPyP (0.5)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
CuTPyP (3)
–
DTBP (3.5)
DTBP (3.5)
DTBP (3.5)
DTBP (3.5)
DTBP (3.5)
DTBP (3.5)
DTBP (3.5)
I2 (3.5)
TBHP (3.5)
PhI(OAc)2 (3.5)
Oxone (3.5)
BPO (3.5)
DDQ (3.5)
O2
DTBP (6.0)
DTBP (2.0)
DTBP (6.0)
DTBP (6.0)
DTBP (6.0)
DTBP (6.0)
DTBP (6.0)
DTBP (6.0)
DTBP (6.0)
–
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
24
6
33
52
72
57
67
66
50
N.D.
10
N.D.
N.D.
Trace
N.D.
N.D.
80
58
N.D.
75
82
80
70
55
9
10
11
12
13
14c
15
16
17d
18e
19
20
21
22
23
24
4
2
6
6
Trace
N.D.
CuTPyP (3)
aReaction condition: methyl 4-hydroxybenzoate (0.5 mmol), 1,4-dioxane (2 mL), catalyst, oxidant, 120 ꢁC.
c
bYields were determined by 1HNMR spectroscopy by using toluene as internal standard. N.D. ¼ not detected. 1 atm O2.
e
d80 ꢁC. 150 ꢁC.
DTBP ¼ di-tert-butyl peroxide. TBHP ¼ tert-butyl hydroperoxide (70% in H2O). BPO ¼ benzoyl peroxide. Oxone ¼
potassium peroxymonosulfate. DDQ ¼ 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
desired products with moderate to excellent yields. Disappointingly, the phenols bearing
–CO2Me or –CN group at meta-position gave 3a (31%) and 6a (N.D.) in low yields.
Acetyl substituted phenols gave excellent yields (Table 2, 12–13a) and afforded corre-
sponding acetal (15a) with 56% yield, even if the naphthol substrate with steric hin-
drance. The results obtained from phenols and naphthol containing aldehyde group
were not ideal (Table 2, 10–11a, 14a), which was probably due to the aldehyde group
was not compatible with the oxidation conditions.[16] Similar to previous studies,[12,17]
the reaction did not produce good results with halogen-substituted phenols or 4-nitro-
phenol as substrates. To sum up, the reaction conditions can be well compatible with
ꢀCO2Me, –CN, –CF3, –COCH3 and –CONR2 groups, poly-substituted phenols and
another aromatic hydroxyl substrate, but the problem of mono-substituted phenols with
EDG remain to be solved (Table 2, 26a–30a). Besides, the p-methoxyphenol could not
react with 1,4-dioxane regardless of which of the five copper porphyrin catalysts men-
tioned above we chose (Table S1). This observation may be caused by the competitive
hydrogen atom transfer (HAT) from 1,4-dioxane and electron-rich phenols to the tert-
butoxyl radical.[18] Unfortunately, when we try to use natural product estrone as the

R
SYNTHETIC COMMUNICATIONSV
2057
Table 2. Substrate scope of phenola.
aReaction conditions: 1 (0.5 mmol), a (2 mL), CuTPyP (3 mol%), DTBP (6.0 equiv.) for 6 h at 120 ꢁC isolated yield based
on phenol. N.D. ¼ not detected.

2058
F.-H. WANG ET AL.
Table 3. Substrate scope of C(sp3)-H reagentsa.
aReaction conditions: 1 (0.5 mmol), a (2 mL), CuTPyP (3 mol%), DTBP (6.0 equiv.) for 6 h at 120 ꢁC, isolated yield based
on phenol. N.D. ¼ not dectected. bReacted for12 h.
Scheme 3. Radicals inhibited experiment.
substrate for preparation of more complex bioactive molecules, no target product could
be detected (Table 2, 31a).
Whereafter, we investigated the reaction of different C(sp3)-H reagents with
methyl 4-hydroxybenzoate 1 as O-H reagent (Table 3). Tetrahydrofuran gave the
desired product in 96% yield after reacting for 12 h (6 h for 45% yield).
Tetrahydropyran and N,N-Dimethylformamide offered 57% and 49% yield (d, h),
respectively. Also, the cyclic ethers (a, c, d, g) gave significantly higher yields than

R
SYNTHETIC COMMUNICATIONSV
2059
Figure 1. EPR spectra of CuTPyP catalyst (black) and reaction mixture (green).
Scheme 4. Proposed reaction mechanism.
acyclic ethers (e, f). Only traces 1e and 1i could be detected under the
same conditions.
To illustrate the mechanism of the reaction, we added free radical scavenger butylated
hydroxytoluene (BHT) or 2,2,6,6-teramethylpyridine-1-oxyl (TEMPO) to the reaction
system and did not detect the desired product. Besides, BHT-dioxane and TEMPO-
dioxane adducts were detected by ESI-MS, respectively (Scheme 3). It indicated that the
reaction involved the formation of 1,4-dioxane free radical. In the equation c), BHT is

2060
F.-H. WANG ET AL.
the tert-butoxyl radical scavenger via HAT. However, 5% yield of BHT-dioxane adduct
could be observed, this indicated that the amount of BHT employed was not sufficient
to fully quench the tert-butoxyl radical and the HAT from the C–H bonds of dioxane
to the radical could not be suppressed completely. The electron paramagnetic resonance
(EPR) spectra of CuTPyP and reaction mixture (Figure 1) also suggested the formation
of carbon radical in the CDC reaction. Previous kinetic isotope effect (KIE) experiments
have proved that the kinetic rate-determining step of this reaction is the cleavage of the
C(sp3)–H bond of 1,4-dioxane.[12,19]
Therefore, based on previous studies,[12,19] a possible reaction pathway in the reaction
was proposed (Scheme 4). In the beginning, Cu(II)TPyP is involved in catalyzing DTBP
homolysis to produce tert-butoxyl radical and tBuO-Cu(III)TPyP species A.[20] The rad-
ical a’ is generated via the HAT reaction from the compound a to tert-butoxyl radical.
And the species A reacts with compound 1 to form complex B. Finally, the reaction of
dioxane free radical a’ and intermediate B releases product 1a and the Cu(II)TPyP cata-
lyst to furnish the catalytic cycle. The electron deficient copper porphyrin CuF20TPP
and CuTPyP exhibit higher catalytic activity than CuTPP, this may be due to the per-
ipheral EWG may enhance Cu–O interaction via electron effect and thus favor the for-
mation of intermediate A and B. Interestingly, the alkyl substituted flat CuTnPP and
puckering CuTtBP also show obviously different activity, suggesting that the spacial
structure of copper porphyrin also has significant effect to the catalyst activity.
Furthermore, the electron-rich phenols are not suitable for current system, most
probably because of the competing HAT from electron-rich phenols and dioxane to
tert-butoxyl radical, which will hinder the formation of dioxane free radical. Also, the
phenols with EDG will strengthen the Cu–O coordination bond in complex B, which
may prevent the release of product.
3. Conclusion
In summary, five copper porphyrins were prepared and used as the catalysts in the
CDC reaction of phenols and ethers to investigate the electronic and spatial effect of
the catalytic reaction. It showed that the peripheral substituents with bulky steric hin-
drance, electron-withdrawing or heteroatom pyridyl groups could improve the catalytic
activity of copper porphyrin in the current CDC reaction. Significantly, CuTPyP was
found a promising catalyst in this reaction with a yield as high as 99% and reduced
reaction time from 12 to 6 h. Various acetal compounds could be obtained in moderate
to excellent yields with good functional group tolerance in the current catalytic system.
4. Experimental procedure
General procedure for synthesis representative example
A solution of methyl hydroxybenzoate (1, 76 mg, 0.5 mmol, 1.0 equiv.) in 1,4-dioxane
(2 mL) was added CuTPyP (10 mg, 0.015 mmol, 3 mol%) and DTBP (520 lL, 3 mmol,
6.0 equiv.) in Schlenk tube. After stirring for 12 h at 120 ꢁC the reaction mixture was
cooled to room temperature and concentrated in vacuum, then purified by column
chromatography (hexane/ethyl acetate (EA)¼5:1).

R
SYNTHETIC COMMUNICATIONSV
2061
Methyl 4-((1,4-dioxan-2-yl)oxy)benzoate (1a)[12]: 99 mg, 83% as white solid, hex/EA¼
1
5:1 (v/v). H NMR (500 MHz, CDCl3) d 7.99 ꢀ 7.92 (m, 2H), 7.09 ꢀ 7.03 (m, 3H), 5.32
(t, J¼2.3 Hz, 1H), 4.11 ꢀ 4.02 (m, 1H), 3.85 (s, 5H), 3.76 (dd, J¼7.4, 2.8 Hz, 2H), 3.56
(dt, J¼11.8, 3.0 Hz, 1H). 13C NMR (126 MHz, CDCl3) d 166.52, 160.23, 131.37, 123.70,
115.71, 93.08, 77.25, 77.00, 76.75, 68.36, 65.95, 60.96, 51.76.
1
Full experimental detail, H NMR and 13C NMR spectra. This material can be found
via the “Supplementary Content” section of this article’s webpage.
Funding
The authors thank the National Natural Science Foundation of China [No. 21671068] and
“Dengfeng Plan” High-level Hospital Construction Opening Project of Foshan Fourth People’s
Hospital [No. FSSYKF-2020012] for the financial support of this work.
References
[1] (a) Evans, R. W.; Zbieg, J. R.; Zhu, S.; Li, W.; MacMillan, D. W. J. Am. Chem. Soc. 2013,
135, 16074–16077. DOI: 10.1021/ja4096472. (b) Zhu, J.; Ren, W.; Tappin, N.; Wang, Q.
Synlett. 2013, 24, 1941–1944. DOI: 10.1055/s-0033-1339472.(c) Sun, K.; Wang, X.; Liu, L.;
Sun, J.; Liu, X.; Li, Z.; Zhang, Z.; Zhang, G. ACS Catal. 2015, 5, 7194–7198. DOI: 10.
1021/acscatal.5b02411.(d) Louillat, M. L.; Patureau, F. W. Chem. Soc. Rev. 2014, 43,
901–910. DOI: 10.1039/C3CS60318K.
[2] (a) F Andres, R.; Wang, Q.; Zhu, J. J. Am. Chem. Soc. 2020, 142, 14276–14285. DOI: 10.
1021/jacs.0c05804. (b) Jarret, M.; Turpin, V.; Tap, A.; Gallard, J. F.; Kouklovsky, C.;
Poupon, E.; Vincent, G.; Evanno, L. Angew. Chem. Int. Ed. 2019, 58, 9861–9865. DOI: 10.
1002/anie.201905227.
[3] (a) Li, C. J. Acc. Chem. Res. 2009, 42, 335–344. DOI: 10.1021/ar800164n. (b) Girard, S. A.;
Knauber, T.; Li, C. J. Angew. Chem. Int. Ed. 2014, 53, 74–100. DOI: 10.1002/anie.
201304268.
[4] (a) Evano, G.; Wang, J.; Nitelet, A. Org. Chem. Front. 2017, 4, 2480–2499. DOI: 10.1039/
C7QO00671C. (b) Gao, J.; Rao, P.; Xu, K.; Wang, S.; Wu, Y.; He, C.; Ding, H. J. Am.
Chem. Soc. 2020, 142, 4592–4597. DOI: 10.1021/jacs.0c00308.(c) Kan, T.; Hosokawa, S.;
Nara, S.; Oikawa, M.; Ito, S.; Matsuda, F.; Shirahama, H. J. Org. Chem. 1994, 59,
5532–5534. DOI: 10.1021/jo00098a009.
[5] (a) Krylov, I. B.; Vil’, V. A.; Terent’ev, A. O. Beilstein J. Org. Chem. 2015, 11, 92–146.
DOI: 10.3762/bjoc.11.13. (b) Chen, L.; Shi, E.; Liu, Z.; Chen, S.; Wei, W.; Li, H.; Xu, K.;
Wan, X. Chem. Eur. J. 2011, 17, 4085–4089. DOI: 10.1002/chem.201100192.(c) Kumar, G.
S.; Maheswari, C. U.; Kumar, R. A.; Kantam, M. L.; Reddy, K. R. Angew. Chem. Int. Ed.
2011, 50, 11748–11751. DOI: 10.1002/anie.201105020.
[6] (a) Nguyen, C. K.; Nguyen, N. N.; Tran, K. N.; Nguyen, V. D.; Nguyen, T. T.; Le, D. T.;
Phan, N. T. S. Tetrahedron Lett. 2017, 58, 3370–3373. DOI: 10.1016/j.tetlet.2017.07.049.
(b) Barve, B. D.; Wu, Y. C.; El-Shazly, M.; Chuang, D. W.; Cheng, Y. B.; Wang, J. J.;
Chang, F. R. J. Org. Chem. 2014, 79, 3206–3214. DOI: 10.1021/jo402798k.(c) Frindy, S.; El
ꢀ
Kadib, A.; Lahcini, M.; Primo, A.; Garcıa, H. ChemistrySelect. 2016, 1, 157–162. DOI: 10.
1002/slct.201600011.
[7] (a) Kumar, G. S.; Pieber, B.; Reddy, K. R.; Kappe, C. O. Chem. Eur. J. 2012, 18,
6124–6128. DOI: 10.1002/chem.201200815. (b) Phan, N. T. S.; Vu, P. H. L.; Nguyen, T. T.
J. Catal. 2013, 306, 38–46. DOI: 10.1016/j.jcat.2013.06.006.(c) Sharma, V.; De, D.;
Bharadwaj, P. K. Inorg. Chem. 2018, 57, 8195–8199. DOI: 10.1021/acs.inorgchem.8b00683.

2062
F.-H. WANG ET AL.
ꢀ
(d) Luz, I.; Corma, A.; Llabres I Xamena, F. X. Catal. Sci. Technol. 2014, 4, 1829–1836.
DOI: 10.1039/c4cy00032c.
[8] (a) Huang, D. L.; Wang, J.; Cheng, F.; Ali, A.; Guo, H. S.; Ying, X.; Si, L. P.; Liu, H. Y.
Microchim. Acta. 2019, 186, 381–392. DOI: 10.1007/s00604-019-3417-6. (b) Lu, K.; He, C.;
Lin, W. J. Am. Chem. Soc. 2014, 136, 16712–16715. DOI: 10.1021/ja508679h.(c) Lu, H.;
Zhang, X. P. Chem. Soc. Rev. 2011, 40, 1899–1909. DOI: 10.1039/C0CS00070A.
[9] (a) Gray, H. B.; Winkler, J. R. Acc. Chem. Res. 2018, 51, 1850–1857. DOI: 10.1021/acs.
accounts.8b00245. (b) Chen, Y.; Zhang, X. P. J. Org. Chem. 2007, 72, 5931–5934. DOI: 10.
1021/jo070997p.(c) Nakagawa, H.; Sei, Y.; Yamaguchi, K.; Nagano, T.; Higuchi, T.
Tetrahedron: Asymmetry. 2004, 15, 3861–3867. DOI: 10.1016/j.tetasy.2004.10.029.
[10] To, W. P.; Liu, Y.; Lau, T. C.; Che, C. M. Chem. Eur. J. 2013, 19, 5654–5664. DOI: 10.
1002/chem.201203774.
[11] (a) Xiong, M. F.; Ali, A.; Akram, W.; Zhang, H.; Si, L. P.; Liu, H. Y. Catal. Commun.
2019, 125, 93–97. DOI: 10.1016/j.catcom.2019.04.001. (b) Wang, H. H.; Wen, W. H.; Zou,
H. B.; Cheng, F.; Ali, A.; Shi, L.; Liu, H. Y.; Chang, C. K. New J. Chem. 2017, 41,
3508–3514. DOI: 10.1039/C6NJ03876J.
[12] Yang, S.; Xiong, M. F.; Tian, W. Q.; Zhang, H.; Xiao, X. Y.; Liu, H. Y.; Chang, C. K.
Tetrahedron. 2020, 76, 131569–131579. DOI: 10.1016/j.tet.2020.131569.
[13] Haber, J.; Matachowski, L.; Pamin, K.; Poltowicz, J. J. Mol. Catal. A Chem. 2003, 198,
215–221. DOI: 10.1016/S1381-1169(02)00688-X.
[14] Senge, M. O.; Bischoff, I.; Nelson, N. Y.; Smith, K. M. J. Porphyrins Phthalocyanines. 1999,
03, 99–116. DOI: 10.1002/(SICI)1099-1409(199902)3:2<99::AID-JPP109>3.3.CO;2-Y.
[15] Jin, L. M.; Xu, P.; Xie, J.; Zhang, X. P. J. Am. Chem. Soc. 2020, 142, 20828–20836. DOI:
10.1021/jacs.0c10415.
[16] Das, R.; Chakraborty, D. Appl. Organometal. Chem. 2011, 25, 437–442. DOI: 10.1002/aoc.
1783.
[17] (a) Font-Sanchis, E.; Aliaga, C.; Cornejo, R.; Scaiano, J. C. Org. Lett. 2003, 5, 1515–1518.
DOI: 10.1021/ol034307p. (b) Simdyanov, I. V.; Zelentsov, S. V. Russ. Chem. Bull. 2006,
55, 207–211. DOI: 10.1007/s11172-006-0238-7.
[18] Yehye, W. A.; Rahman, N. A.; Ariffin, A.; Abd Hamid, S. B.; Alhadi, A. A.; Kadir, F. A.;
Yaeghoobi, M. Eur. J. Med. Chem. 2015, 101, 295–312. DOI: 10.1016/j.ejmech.2015.06.026.
[19] Zhao, J.; Fang, H.; Zhou, W.; Han, J.; Pan, Y. J. Org. Chem. 2014, 79, 3847–3855. DOI:
10.1021/jo500192h.
[20] Yi, H.; Zhang, G.; Wang, H.; Huang, Z.; Wang, J.; Singh, A. K.; Lei, A. Chem. Rev. 2017,
117, 9016–9085. DOI: 10.1021/acs.chemrev.6b00620.