Regioselectivity-Switchable Intramolecular Hydroarylation of Ynone

Article abstract of DOI:10.1002/adsc.202001152

The switchable catalytic approach to the regioselective intramolecular hydroarylation of ynone has been developed. When ZnI₂ was used as catalyst, the umpolung α-arylation of ynone was realized via an addition-elimination process of iodine ion to generate the ortho-phenanthrenequinone methide (o-PQM), which could be trapped by styrene to form benzo[f,h]chromenes through hetero-Diels-Alder reaction. While IPrAuCl/AgSbF₆ was applied, however, the β-arylation of ynone took place to afford benzocycloheptene-5-ones in moderate to excellent yields. (Figure presented.).

Full text of DOI:10.1002/adsc.202001152

Title: Regioselectivity-Switchable Intramolecular Hydroarylation of
Ynone
Authors: Shifa Zhu, Feng Wu, and Shiwei Lu
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Adv. Synth. Catal. 10.1002/adsc.202001152
Link to VoR: https://doi.org/10.1002/adsc.202001152

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.202((will be filled in by the editorial staff))
Regioselectivity-Switchable Intramolecular Hydroarylation of
Ynone
Feng Wu,a Shiwei Lu,a and Shifa Zhu*a
a
Key Lab of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical
Engineering, South China University of Technology, Guangzhou 510640, P. R. China, E-mail: zhusf@scut.end.cn
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.
Abstract. The switchable catalytic approach to the
regioselective intramolecular hydroarylation of ynone has
been developed. When ZnI2 was used as catalyst, the
umpolung α-arylation of ynone was realized via an
addition-elimination process of iodine ion to generate the
ortho-phenanthrenequinone methide (o-PQM), which
could be trapped by styrene to form benzo[f,h]chromenes
through
hetero-Diels-Alder
reaction.
While
IPrAuCl/AgSbF6 was applied, however, the β-arylation of
ynone took place to afford benzocycloheptene-5-ones in
moderate to excellent yields.
Keywords: ynone; catalyst selective synthesis;
regioselective hydroarylation; phenanthrenequinone
methides; umpolung
Scheme 1. Background and challenges of this work.
Although some examples using aryl groups as
nucleophiles in oxidative α-arylation of ynone via
gold-catalyzed carbenoid transfer process were
reported recently,[5] the development of efficient
regioselective α-hydroarylation of ynone is highly
desirable and challenging.
Ynones are easily available and highly useful
molecules, which have often been applied as diverse
building blocks to access to a wide range scaffolds.[1]
One of the most important reaction type of ynones is
1,4-Michael addition to provide the β-addition
products (Scheme 1A).[2] However, direct attack of the
ynones at α-position is unfavored due to the inherent
electronic characteristics. The classical Morita-Baylis-
Hillman (MBH) reaction gives access to umpolung α-
addition product of enones.[3] Similar umpolung
process was also observed in the phosphine-catalyzed
transformation of ynones (Scheme 1B).[4] Since the
pioneering work of Trost group,[4a] umpolung α-
addition of ynone facilitated by phosphine with hetero-
nucleophiles, such as O-H (alcohol, phenol),[4b] N-H
(amide, aniline, aromatic nitrogen heterocycle)[4a,c-d]
and S-H (thioalcohol)[4e] were well established. As for
carbon nucleophiles, the use of cyanide[4f] and
enolate[4g] were also investigated. However, in the case
of aromatic carbon nucleophiles without acidic proton,
the aromaticity and lower nucleophilicity increase the
reaction activation energy barrier. Furthermore, the
protonation of the phosphonium zwitterion would be
impeded in the absence of an acidic proton. Comparing
with nucleophiles mentioned above, the umpolung α-
hydroarylation of ynone has not yet been reported.
Underpinned by the concept of catalyst selective
synthesis,[6] simple starting materials can rearrange
into different scaffolds.[7] As part of our continuous
effects in developing practical transformations of
ynones,[8] we herein describe the successful
intramolecular regioselective hydroarylation of 2-
arylphenyl alkynyl ketone with different aromatic
nucleophiles (Scheme 1C). Employing ZnI2 or cationic
gold(I) as catalyst, both the α- and β-arylation products
could be achieved selectively. From a synthetic point-
of-view, the intramolecular α-hydroarylation of 2-
arylphenyl alkynyl ketone would afford the ortho-
phenanthrenequinone methides (o-PQM), which is an
important intermediate in the construction of benzo-
fused O-heterocycles via hetero-Diels-Alder reaction.
Until now, the o-PQM intermediate has very restricted
substrate scope and has not been widely utilized since
it was firstly reported in 1969[9] owing to the lack of
convenient precursors.[10]
The o-thienyl substituted alkynyl ketone 1a was
initially chosen to explore the hydroarylation (Table 1),
1
This article is protected by copyright. All rights reserved.

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
Table 1. Optimization of the regioselective cyclization. [a,b]
Table 2. Substrate scope of the α-arylation/[4+2] reaction.
Temp.
(◦C) [%]
3aa
4a 1a
[%] [%]
Entry
Catalyst ([%])
Sol.
1
2
3
4
5
6
7
8
PtCl2 (5)
PdCl2 (10)
IPrAuBF4 (5)
In(OTf)3 (10)
Zn(OTf)2 (20)
Cu(OTf)2 (10)
ZnCl2 (20)
ZnBr2 (20)
ZnI2 (20)
DCE 100
DCE 100
-
-
-
-
-
-
-
70
-
-
-
-
-
-
-
nr
nr
0
nr
nr
0
65
-
-
DCE
DCE
25
80
DCE 100
DCE
DCE
DCE
DCE
PhMe
80
80
80
80
80
-
10
32
41
17
37
52
62
88
74
-
9
10
11
12
13
14
15
16[c]
ZnI2 (20)
ZnI2 (50)
ZnI2 (50)
69
42
0
PhMe 100
PhH 100
PhCl 100
-
-
ZnI2 (50)
-
0
ZnI2 (50)
PhF
PhF
100
100
80
-
0
ZnI2 (30)
-
0
PPh3AuBF4 (5)
DCE
DCE
DCE
-
nr
0
17[c] tBuPhosAuNTf2 (5)
18[c]
a)
25
-
78
95
IPrAuSbF6 (5)
25
-
0
The reaction was performed under N2 for 12 h; 1a (0.1
b)
mmol) in 1 mL solvent, 2a:1a=2:1(mol ratio). The yield
and dr value were determined by H NMR spectroscopy
1
with dimethyl terephthalate as internal standard; the dr value
Reaction condition: 1 (0.2 mmol), 2 (0.4 mmol), 50 mmol%
of 3aa was >95:5. c) Without 2a.
ZnI2 in 2 mL PhF were stirred at 100 ◦C. Isolated yield. The
1
dr value were determined by H NMR of crude products.
given that S-containing fused heteroarenes with rigid
planar backbones and extended π-conjugation have
received tremendous attention due to their electronic
and optical characteristics.[11] The 4-Me-styrene 2a
was applied as the 2π component to trap the unstable
α-arylation product, o-PQM intermediate. Typical
transition metal catalysts, which were reported
efficiently for the hydroarylation of electron-neutral
alkyne were tested first. PtCl2 and PdCl2 were
ineffective in this reaction (entries 1 and 2).While the
cationic gold(I) salt only afforded the β-arylation
product 4a (entry 3). Other Lewis acid catalysts, such
as In(OTf)3, Cu(OTf)2 and Zn(OTf)2, were also tested,
but only resulted in no reaction or complex mixtures
(entries 4-6). To our delight, the desired product 3aa
was obtained in 10% NMR yield when ZnCl2 was used
as catalyst (entry 7). During the evaluation of zinc
halides, a significant improvement in the yield of 3aa
was observed with ZnI2 (entry 9). A higher yield based
on recovered starting material (17%, brsm: 55%) was
obtained when using PhCH3 as solvent (entry 10). The
efficiency of the reaction can be promoted by
increasing the reaction temperature (100 ℃) and the
catalyst loading (entry 11). Solvent effects were further
revealed using aromatic solvents with different
electronic effects (entries 11-14). The highest yield
(88%) was achieved in PhF solvent. Attempts to
Unless otherwise noted, the dr value was >95:5.
decrease the loading of ZnI2 indicated that 50 mol% of
catalyst was necessary to achieve superior
performance (entries 14-15). Furthermore, the optimal
condition of the β-arylation was also identified (see
Supplementary information).
Having optimized reaction conditions in hand, we
then explored the reaction scope of the α-arylation
(Table 2). Styrene derivatives with different electron-
donating and -withdrawing groups could be used as
effective 2π components to react with the proposed o-
PQM intermediate to afford the fused O-heterocycles
3aa-af in 62-85% yields. A wide range of
benzo[h]thieno[3,2-f]chromenes possessing both
electron-donating as well as -withdrawing groups
could be conveniently assembled in 65-95% yields
(3ba-ea). It’s remarkable that the electron donating 4-
MeO-C6H4 at the alkyne terminal provided the
corresponding products in a reduced yield and
relatively poor dr value (3da). Similarly, the negative
effects of the electron-rich 3-thienyl and 2-naphthyl
were also observed in products 3fa (52%, dr = 85:15)
and 3ga (46%, dr = 92:8). Substrates bearing electron-
donating groups on the nucleophilic thiophene rings
(Ar2) underwent effectively to corresponding products
2
This article is protected by copyright. All rights reserved.

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
(3ia and 3ja), while the substrate with an electron- served as an effective substrate, leading to the product
deficient thiophene resulted in no conversion (3ka). 4h in 60% yield. For the nucleophilic Ar2 group,
Thienylene-fused (Ar1) ynone was compatible with substituted-thioenyl, benzothioenyl, benzofuran, and
this reaction as well, which provided the product 3la, electron- rich phenyl group were all well applicable for
albeit with diminished yield (28%). The generality of this protocol to provide the corresponding products in
this novel method to the α-arylation was also 50-96% yields (4i-s). However, substrate with
demonstrated by the displacement of the 2-thienyl to electron-neutral Ar2 (4t) turned out to be inactive as it
other O- or S- containing heteroarenes (3ma-qa). The performed in the α-arylation process.
hydroarylation of the 3-thienylphenyl alkynyl ketone
took place regiospecifically at the 2-position of the
thienyl group to afford the benzo[h]thieno[2,3-
f]chromene (3ma). Both benzothiophene and
benzofuran substituted (Ar2) ynones exhibited high
reactivity, and the corresponding products 3na-qa
were obtained in 46-97% yields. The relatively poor dr
value were obtained in the case of 2-substituted
benzothiophene and benzofuran (3na and 3oa). Finally,
ynones with substituted phenyl rings (Ar2) were also
investigated and the α-arylation happened at the less-
hindered ortho position of the 1,1'-biphenyl bonds to
afford 3ra and 3sa in yields of 54% and 85%. The
electron-donating MeO- in Ar2 was proven necessary,
given that only the starting materials were recovered in
the attempt for the synthesis of 3ta.
With the advent of the successful regioselective α-
arylation/[4+2] cascades, we next focused on the β-
arylation of ynones (Table 3). It is relatively easier for
β-arylation than α-arylation, presumably due to the
inherent electronic characteristics. The reaction could
be easily extended to different substrates and provided
an array of cyclohepten-5-ones in 50-96% yields (4a-
s). It seems the electronic properties of Ar1 and R in the
substrates have little effect on the reaction results,
giving the desired products in 71-93% yields (4a-g). It
is notable that the alkyl-substituted ynone could be
Scheme 2. Derivatization reactions of product 4a. Reaction
conditions: (a)2-bromo-1,1'-biphenyl, n-BuLi, THF, -78 ◦C-
rt; (b) AcOH, 100 ◦C.
To highlight the synthetic utility of β-arylation
products, several derivatizations of 4a were performed
(Scheme 2). The reduction of the carbonyl group
generated cycloheptatriene 5a (94%). Bromination of
product 4a with NBS afforded the double bromination
product 5b (63%). The ring expansion with TMS-
CHN2 provided practical access to cyclooctrienone 5c
(64%). Finally, the spiro-cyclooctriene/fluorene
system 5d, which was largely applied in OLED
materials,[10] was assembled in
transformation (72%).
a
two-step
Lastly, we turned our attention to investigate the
mechanism of the umpolung α-arylation. The hetero-
Diels-Alder dimerization of o-PQM gave convincing
evidence of the formation of corresponding
intermediates.[9] Indeed, the dimerization product 6a
was obtained when ynone 1a was treated with ZnI2 in
the absence of styrene (Scheme 3A). It was noticed that
50 mol% ZnI2 was necessary to efficiently promote this
α-hydroarylation, which indicates that the iodine ion
might participate in the reaction. This proposition is
pursued with ynones during the development of halo
aldol reactions[13], which were typically mediated by
Lewis acids. Toward this, substrate 1a was subjected
using Zn(OTf)2 as catalyst and NaI (1.0 equiv) as
iodine source (Scheme 3B). The desiring α-
hydroarylation/[4+2] product was obtained in 79%
yield, while the absence of either Zn(OTf)2 or NaI only
led to recovery of 1a. These results indicated the
combination of Zn(II) and iodine ion was crucial for
the α-hydroarylation. Inspired by the halo aldol
reaction,[13] we proposed the iodine ion might act as an
umpolung nucleophile to form an allenoate
intermediate[5a]. Given the HOAc/NaOAc buffer was
employed to facilitate the protonation in Trost’s
original report,[4a] we envisioned that the proposed
allenoate could also be protonated by HOAc (Scheme
Table 3. Substrate scope of the β-arylation reaction.
Reaction condition: 1a (0.2 mmol), IPrAuCl/AgSbF6 (2%
mmol) in 2 mL DCE were stirred at 25 ◦C; Isolated yield.
3
This article is protected by copyright. All rights reserved.

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
interaction, the regioselectivity at less hindered
positions when using phenyl nucleophiles (3ra and 3sa)
is also explained (Figure 1C).
In summary, we have established a divergent
catalytic
approach
for
the
regioselective
hydroarylation of ynones. For the umpolung α-
arylation process, ZnI2 was served as both Lewis acid
and iodine source to facilitate the formation of o-PQM
intermediates via an addition/elimination process of
iodine ion; the resulted o-PQM intermediate were then
trapped by styrene to yield [4+2] products 3. While the
cationic gold(I) salt was used as catalyst, the 7-endo-
dig cyclization[17] was achieved to afford cyclohepten-
5-ones 4 in good to excellent yields.
Scheme 3. Mechanistic studies.
3C). The treatment of 1a under ZnI2 and HOAc
resulted in complex mixture of products, only trace
amount of dimer 6a was identified. In order to rule out
the interference of the nucleophilic moiety, simple
ynone 1a' was adopted and the desired β-iodine vinyl
ketone 7a' was achieved in 29% yield, which supports
the formation of the allenoate 1a-I during the
reaction.[14]
Experimental Section
General Experimental Procedure for the α-arylation/
[4+2] reaction (3aa-3sa):
In a Schlenk tube with a magnetic bar was added ZnI2 (50
mol%), PhF (2mL), substrates (0.2mmol) and styrene (0.4
mmol) respectively. The mixture was stirred at 100 oC until
the starting materials was completely consumed monitored
by TLC. After that, the solvent was evaporated, and the
residue was purified by flash column chromatography to
afford the pure products.
Based on the above experimental evidence, a
plausible mechanism is proposed in Figure 1A. Initial
Lewis acid catalyzed iodo-Michael addition at the β-
position gives the allenoate intermediate 3-I. Then the
6π cyclization[15] undergoes followed by isomerization
to form intermediate 3-III. Finally, the elimination of
iodine from 3-III affords the formal α-arylation
product, o-PQM intermediates, and regenerates iodine
ion. The cis diastereoselective outcome could be
attributed to the secondary orbital overlap between the
aryl group of styrene and the π-system of o-PQM
intermediates.[16] The relatively poor dr value found in
the case of substrates with 2-substitued
benzothiophene and -furan (3na and 3oa) was due to
the deflective distribution to Z isomer owing to the
steric interaction between the R group and the
nucleophilic Ar (Figure 1B). Base on the same steric
General Experimental Procedure for the β-arylation
reaction (4a-4s):
In a Schlenk tube with a magnetic bar was added 2 mol%
IPrAuCl/AgSbF6 and 2 mL DCE. After the mixture was
stirred for 5 min, substrates (0.2mmol) was added. The
mixture was stirred at 25 oC until the starting materials was
completely consumed monitored by TLC. After that, the
solvent was evaporated, and the residue was purified by
flash column chromatography to afford the pure product.
Acknowledgements
This work was supported by the Ministry of Science and
Technology of the People’s Republic of China (2016YFA0602900),
the NSFC (22071062, 21871096, 21672071), Guangdong Science
and
Technology
Department
(2018B030308007,
2018A030310359).
References
[1] a) C. Nájera, L. K. Sydnes, M. Yus, Chem. Rev. 2019,
119, 11110; b) G. Abbiati, A. Arcadi, F. Marinelli, E.
Rossi, Synthesis 2014, 46, 687; c) R. Whittaker, A.
Dermenci, G. Dong, Synthesis 2015, 48, 161.
[2] a) S. Mori, E. Nakamura, K. Morokuma,
Organometallics 2004, 23, 1081; b) R. S. Menon, M. G.
Banwell, Org. Biomol. Chem. 2010, 8, 5483; c) J. T. R.
Liddon, M. J. James, A. K. Clarke, P. O’Brien, R. J. K.
Taylor, W. P. Unsworth, Chem. - A Eur. J. 2016, 22,
8777; d) X. Zhang, R. C. Larock, J. Am. Chem. Soc. 2005,
127, 12230; e) Q. Lan, X. Wang, S. Shirakawa, K.
Maruoka, Org. Process Res. Dev. 2010, 14, 684; f) R.
Spina, E. Colacino, B. Gabriele, G. Salerno, J. Martinez,
F. Lamaty, Org. Biomol. Chem. 2012, 10, 9085; g) K. Ji,
Figure 1. Proposed mechanism.
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
F. Yang, S. Gao, J. Tang, J. Gao, Chem. - A Eur. J. 2016, [16] a) Y. F. Wong, Z. Wang, W.-X. X. Hong, J. Sun,
22, 10225.
Tetrahedron 2016, 72, 2748; b) C.-C. Hsiao, S. Raja, H.-
H. Liao, I. Atodiresei, M. Rueping, Angew. Chem. 2015,
127, 5854; Angew. Chem. Int. Ed. 2015, 54, 5762.
[17] a) Y. Chen, X. Liu, M. Lee, C. Huang, I. Inoyatov, Z.
Chen, A. C. Perl, W. H. Hersh, Chem. - A Eur. J. 2013,
19, 9795; b) K. Wilckens, M. Uhlemann and C.
Czekelius, Chem. - A Eur. J., 2009, 15, 13323; c) V. A.
Peshkov, O. P. Pereshivko and E. V. Van der Eycken,
Adv. Synth. Catal., 2012, 354, 2841.
[3] a) K. Morita, Z. Suzuki, H. Hirose, Bull. Chem. Soc. Jpn.
1968, 41, 2815; b) H. Ni, W.-L. Chan, Y. Lu, Chem. Rev.
2018, 118, 9344.
[4] a) B. M. Trost, G. R. Dake, J. Am. Chem. Soc. 1997, 119,
7595; b) S. Gabillet, D. Lecerclé, O. Loreau, S. Dézard,
J.-M. Gomis, F. Taran, Synthesis 2007, 2007, 515; c) I.
Yavari, S. Souri, M. Sirouspour, H. Djahaniani,
Synthesis 2006, 2006, 3243; d) I. Yavari, H. Norouzi-
Arasi, Phosphorus. Sulfur. Silicon Relat. Elem. 2002,
177, 87; e) S. Gabillet, D. Lecerclé, O. Loreau, M.
Carboni, S. Dézard, J.-M. Gomis, F. Taran, Org. Lett.
2007, 9, 3925; f) A. Siby, O. Loreau, F. Taran,
Synthesis2009, 2009, 2365; g) H.-L. Liu, H.-F. Jiang,
Tetrahedron 2008, 64, 2120; h) A. Mondal, R. Hazra, J.
Grover, M. Raghu, S. S. V. Ramasastry, ACS Catal. 2018,
8, 2748.
[5] a) J. Li, F. Yang, Y. Ma, K. Ji, Adv. Synth. Catal. 2019,
361, 2148–2153; b) K. Ji, F. Yang, S. Gao, J. Tang, J.
Gao, Chem. - A Eur. J. 2016, 22, 10225–10229; c) Z.-S.
Chen, F. Yang, H. Ling, M. Li, J.-M. Gao, K. Ji, Org.
Lett. 2016, 18, 5828–5831.
[6] J. Mahatthananchai, A. M. Dumas, J. W. Bode, Angew.
Chem. 2012, 124, 11114; Angew. Chem. Int. Ed. 2012,
51, 10954.
[7] a) J. T. R. Liddon, M. J. James, A. K. Clarke, P. O’Brien,
R. J. K. Taylor, W. P. Unsworth, Chem. - A Eur. J. 2016,
22, 8777; b) J.-J. Feng, J. Zhang, ACS Catal. 2017, 7,
1533; c) J. D. Dooley, S. Reddy Chidipudi, H. W. Lam,
J. Am. Chem. Soc. 2013, 135, 10829.
[8] a) L. Chen, K. Chen, S. Zhu, Chem 2018, 4, 1208; b) L.
Chen, Z. Liu, S. Zhu, Org. Biomol. Chem. 2018, 16, 8884;
c) F. Wu, S. Zhu, Org. Lett. 2019, 21, 1488.
[9] W. W. Sullivan, D. Ullman, H. Shechter, Tetrahedron
Lett. 1969, 10, 457.
[10] a) J. Matsumoto, M. Ishizu, R. Kawano, D. Hesaka, T.
Shiragami, Y. Hayashi, T. Yamashita, M. Yasuda,
Tetrahedron 2005, 61, 5735; b) D. N. Nicolaides, S. G.
Adamopoulos, E. J. Hatzigrigoriou, K. E. Litinas, J.
Chem. Soc. Perkin Trans. 1 1991, 9, 3159.
[11] C. Zhang, X. Zhu, Acc. Chem. Res. 2017, 50, 1342.
[12] a) C. T. Chen, Y. Wei, J. S. Lin, M. V. R. K. Moturu,
W. S. Chao, Y. T. Tao, C. H. Chien, J. Am. Chem. Soc.
2006, 128, 10992; b) Y. Wei, S. Samori, S. Tojo, M.
Fujitsuka, J. S. Lin, C. T. Chen, T. Majima, J. Am. Chem.
Soc. 2009, 131, 6698.
[13] a) G. Li, X. Xu, D. Chen, C. Timmons, M. D. Carducci,
A. D. Headley, Org. Lett. 2003, 5, 329; b) B. K. Senapati,
G. S. Hwang, S. Lee, D. H. Ryu, Angew. Chem. 2009,
121, 4462; Angew. Chem. Int. Ed. 2009, 48, 4398.
[14] a) V. A. F. Da Silva, G. P. Da Silva, B. T. Matsuo, A.
Ali, R. L. Davis, J. Zukerman-Schpector, A. G. Corrêa,
M. W. Paixão, Org. Biomol. Chem. 2019, 17, 519; b) X.
Zeng, Z. Lu, S. Liu, G. B. Hammond, B. Xu, J. Org.
Chem. 2017, 82, 13179.
[15] a) A. Fürstner, V. Mamane, J. Org. Chem. 2002, 67,
6264; b) X. Zeng, Z. Lu, S. Liu, G. B. Hammond, B. Xu,
J. Org. Chem. 2017, 82, 13179; b) J. W. Dankwardt,
Tetrahedron Lett. 2001, 42, 5809; c) H. Luo, C. He, H.
Jiang and S. Zhu, Chin. J. Chem., 2020, 38, 1052.
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.202001152
Advanced Synthesis & Catalysis
COMMUNICATION
Regioselectivity-Switchable Intramolecular
Hydroarylation of Ynone
Adv. Synth. Catal. Year, Volume, Page – Page
Feng Wu, Shiwei Lyu and Shifa Zhu*
6
This article is protected by copyright. All rights reserved.