Divergent Access to Benzocycles through Copper-Catalyzed Borylative Cyclizations

Article abstract of DOI:10.1002/adsc.202100812

A copper-catalyzed chemodivergent approach to five- and six-membered benzocycles from dienyl arenes tethered with a ketone has been developed. Through proper choice of coordinating ligands and catalytic conditions, copper-catalyzed borylative cyclization of a single dienyl arene can be diverted to two different pathways, leading to indanols and dihydronaphthalenols with high stereoselectivity. The chiral bidentate bisphosphine ligand (S,S)-Ph-BPE was optimal for asymmetric copper-allyl addition to a tethered ketone via a boat-like transition state, whereas NHC ligands led to boro-allyl addition producing indanols with high diastereoselectivity. (Figure presented.).

Full text of DOI:10.1002/adsc.202100812

RESEARCH ARTICLE
doi.org/10.1002/adsc.202100812
Divergent Access to Benzocycles through Copper-Catalyzed
Borylative Cyclizations
Wan Seok Yoon,a Jung Tae Han,a and Jaesook Yuna,*
a
Department of Chemistry and Institute of Basic Science, Sungkyunkwan University, Suwon, 16419, Korea
E-mail: jaesook@skku.edu
Manuscript received: June 30, 2021; Revised manuscript received: August 11, 2021;
Version of record online: ■■■, ■■■■
Supporting information for this article is available on the WWW under https://doi.org/10.1002/adsc.202100812
Abstract: A copper-catalyzed chemodivergent approach to five- and six-membered benzocycles from dienyl
arenes tethered with a ketone has been developed. Through proper choice of coordinating ligands and catalytic
conditions, copper-catalyzed borylative cyclization of a single dienyl arene can be diverted to two different
pathways, leading to indanols and dihydronaphthalenols with high stereoselectivity. The chiral bidentate
bisphosphine ligand (S,S)-Ph-BPE was optimal for asymmetric copper-allyl addition to a tethered ketone via a
boat-like transition state, whereas NHC ligands led to boro-allyl addition producing indanols with high
diastereoselectivity.
Keywords: Allylation; Asymmetric Cyclization; Benzocycles; Copper; Divergent Synthesis
Introduction
Benzocycles containing five- and six-membered
carbocyclic rings are common core structures of
biologically active molecules and natural products
and thus, serve as attractive targets in organic
synthesis and the pharmaceutical industry.[1] While
many methods have been extensively practiced for
their synthesis,[2] catalytic divergent approaches to
variously-sized benzocycles from the same starting
material with good stereocontrol are rare and
challenging. Since divergent approaches provide
great potential to build target molecules efficiently
in a single synthetic operation with a slight
modification of catalytic conditions,[3] the develop-
ment of such processes is highly desirable.
Copper-catalyzed difunctionalizations of unsatu-
rated CÀ C bonds have become valuable synthetic
methods due to their high efficiency and synthetic
versatility over the past decade.[4] In particular, con-
jugate dienes as π-substrates are challenging substrates,
as they can produce a complex mixture of isomeric
products, including (E)-, (Z)-alkenyl isomers and
Scheme 1. Catalyst Controlled Functionalization of Dienes.
regioisomers. However, recent advances in copper- electrophiles.[5] In addition, along with the develop-
catalyzed functionalization of dienes delivered selec- ment of ligand-controlled regiodivergent borofunction-
tive formation of a single isomeric product with good alization of terminal alkenes,[6a,b] allenes,[6c,d] and
diastereo- and/or enantio-control by trapping in-situ alkynes,[6e] regiodivergent borofunctionalizations of
generated allyl copper intermediates with various conjugate dienes disclosed by the Procter group and
Adv. Synth. Catal. 2021, 363, 1–8
1
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
Table 1. Optimization.
Isolated yield (%)
entry
conditions
2a:3a-Bpin[a]
2a
3a[b]
1[c]
2[c]
3[c]
4
IPrCuCl, LiOtBu
SiMesCuCl, LiOtBu
IMesCuCl, LiOtBu
>20:1
>20:1
>20:1
>20:1
>20:1
>20:1
>20:1
1:1.6
57
61
69
57
86
54
45
–
–
–
–
–
–
–
–
IMesCuCl, LiOtBu, 1 equiv. MeOH
IMesCuCl, LiOMe, 1 equiv. MeOH
CuCl, 2 equiv. PPh3, LiOtBu
CuCl, Xantphos, NaOtBu
CuCl, (S)-BINAP, NaOtBu
CuCl, (S)-Segphos, NaOtBu
CuCl, (R,S)-Josiphos, NaOtBu
CuCl, (S,S)-Ph-BPE, NaOtBu
5
6[c]
7
8
9
10
11
60 (62% ee)
43 (63% ee)
72 (0% ee)
76 (92% ee)
1:0.9
1:>20
1:>20
–
–
–
[a] Determined by crude 1H NMR analysis and reaction was conducted on a 0.2 mmol scale of 1a.
[b] The corresponding hydroxy compound (3a) was obtained by NaBO3 ·4H2O oxidation of 3a-Bpin in THF/H2O.
[c] 1.05 equiv. of base was used.
Brown group have provided ready access to functional- moiety with bis(pinacolato)diboron (B2pin2) by varying
ized regioisomeric derivatives of π-bonds in one ligands for copper (Table 1 and Figure 1). In our initial
operation[7] (Scheme 1a); e.g. borocyanation[7a,b] and survey, we focused on NHC (=N-heterocyclic car-
boroarylation with palladium cocatalyst.[7c,d]
bene) ligands, which previously led to highly diaster-
With our continued interests in the development of eoselective azepine synthesis from imine-tethered
new asymmetric synthetic methods using CuÀ H and arenyl dienes,[8a] and found that NHC ligands gave the
CuÀ B catalysts, we recently focused on intramolecular unexpected 5-membered cyclic compound 2a instead
functionalization of dienes with an aryl-tethered func- of the 6-membered dihydronaphthalenol derivative
tional group.[8] Previously, we reported copper-cata- (3a-Bpin) (entry 1–3). Among the screened
lyzed intramolecular borylative[8a,9] and reductive NHCÀ CuCl precursors, IMesCuCl afforded 2a in good
cyclization[8b] of dienes tethered with an imine group yield as the major diastereomer without detectable
affording 7-membered benzazepine derivatives with formation of 3a-Bpin using LiOtBu as the base
high diastereo- and enantioselectivity through a (entry 3). We suspected that the formation of 2a would
strained cyclic transition state (Scheme 1b). In this result from proton sources in the reaction mixture such
context, our investigation with dienyl arene compounds as tBuOH formed from the enolizable ketone moiety
with a carbonyl group[8c] that can generate smaller
benzocycles via borylative cyclization was initiated.
Herein, we describe a copper-catalyzed chemodiver-
gent approach to five- and six-membered benzocycles
from the same dienyl compounds with a tethered
ketone substituent with high stereoselectivity; a simple
switch in readily available ligands under catalytic
conditions results in a chemodivergent pathway lead-
ing to five- and six-membered carbocycles with high
selectivity (Scheme 1c).
Results and Discussion
We started our investigation by examining copper-
catalyzed borylative coupling of the simple 1,3-dienyl
arene compound (1a) containing a methyl ketone
Figure 1. Structures of the Ligands.
Adv. Synth. Catal. 2021, 363, 1–8
2
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
by the alkoxide base and inadvertent water, and thus were appropriate for the formation of corresponding
decided to include additional proton sources (entries 4 indanols (2d and 2e), but dihydronaphthalenol for-
and 5). Indeed, the addition of 1 equivalent of MeOH mation were less efficient, resulting in decreased
with LiOMe as the base offered the best results, yield or ee.
yielding 2a in 86% yield with 96:4 diastereomeric
ratio, which was chosen for the optimal conditions for aromatic ring of dienyl arenes were investigated. In
synthesis of 5-membered benzocycles 2 (entry 5). general, all substrates with either electron-donating
The effect of different substituents (R2) on the
Phosphine ligands such as PPh3 and Xantphos also (1f–1h) or electron-withdrawing substituents (1i–1l)
produced 2a, but in lower yields (entries 6 and 7). produced the corresponding indanols (2f–2l) in mod-
When the C2 symmetric chiral bisphosphine ligands, erate to good yield with high diastereoselectivity under
BINAP and Segphos were used with the NaOtBu base, condition A. However, in cases of 6-membered ring
1
both 2a and 3a-Bpin formed in a ~1:1 ratio via H formation, substrates with an electron-donating or
NMR analysis, and the corresponding hydroxy com- electron withdrawing group were slightly less efficient
pound 3a was isolated in moderate yield and ee after than neutral substrates, giving cyclized products (3) in
oxidation instead of unstable 3a-Bpin (entries 8 and moderately reduced yield or ee. Especially, in the case
9). The use of Josiphos ligand was not suitable for the of the strongly electron-withdrawing CF3-containing
formation of 3a, yielding a racemic product (0% ee) substrate 1i, the intramolecular copper-allyl cyclization
despite its improved yield. Finally, the optimal ligand was not very effective, forming the indanol byproduct
for the asymmetric formation of 3a was found to be 2i in a ~1:1 ratio.
(S,S)-Ph-BPE ligand with a high enantioselectivity
Next, we tried to explain the reaction pathways to
(92% ee) and with no detectable formation of 2a. The benzocycles 2 and 3 (Scheme 3). With IMesCu
relative configuration of 2a[10] was determined by catalyst, when the reaction was carried out without
NOE experiments (See SI, Fig S1) and the absolute additional MeOH in a glovebox, a low yield of 2a was
configuration of 3a was determined by X-ray crystal obtained. The yield increased to 67% through the
analysis of the corresponding 4-bromobenzoate deriva- addition of 0.5 equiv. of MeOH. Moreover, the
tive of 3a, which contained two molecules in a unit addition of 1 equiv. of MeOD resulted in 66%
cell (Figure 2).[11]
deuterium incorporation to the benzylic carbon of 2a,
Having established conditions for 2a and 3a, we indicating protonation of the benzylic CuÀ C bond
surveyed the scope of copper-catalyzed chemodiver- (Scheme 3a). Therefore, for IMesCu catalyst,[8a] it was
gent intramolecular cyclization of dienyl arenes (2) proposed that copper-catalyzed intramolecular addition
using condition A or B (Scheme 2). First, scaled-up of IMes-copper allyl intermediate III was not facile,[12]
reactions of 1a under both conditions were carried undergoing protonation of the CuÀ C bond by proton
out and each product was formed with no significant sources to yield (Z)-allylboronate IV.[13,14] Subsequent
change in yield or enantioselectivity. Dienyl arenes intramolecular cyclization of the allylboronate[15] to the
with an alkyl-substituted ketone moiety (R1 = alkyl; carbonyl group produced racemic indanols 2 with high
1b and 1c) were suitable for both reactions, yielding diastereoselectivity. Also, DFT calculations showed
each benzocycle in good yield and with high that IMes-copper allyl complex III did not allow
enantioselectivity for dihydronaphthalenols (3b and structural rotations necessary for the copper-allyl
3c). Substrates with an aromatic substituent (R1 =Ar) addition, requiring high activation energy of 20.2 kcal/
mol (See SI, Fig S4).
In the case of copper-BPE catalyst, copper-allyl
addition to the ketone moiety[17] efficiently occurs,
yielding dihydronaphthalene derivative (3a-Bpin) with
good enantioselectivity. Detailed density functional
theory (DFT) calculations were carried out (Sche-
me 3b). Copper-allyl intermediate I, a formal 1,4-
borocupration product is generated by 1,2-borocupra-
tion of the diene 1a and subsequent allylic
isomerization.[8,16] Then, intermediate I undergoes
intramolecular cyclization to produce the dihydronaph-
thalenol derivative (3a) through copper-catalyzed
allylation. Although attaining a favorable transition
state was expected to be difficult due to a low level of
flexibility, the copper-BPE catalyst was highly efficient
for preferred production of 3a via a boat-like transition
state with relatively low activation energy of 3.1 kcal/
mol (TS-I). Overall, the proposed catalytic cycles for
Figure 2. X-ray Structure of 4-bromobenzoate of 3a.
Adv. Synth. Catal. 2021, 363, 1–8
3
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
Scheme 2. Substrate Scope of the Intramolecular Cyclization of Dienyl Arenes (1).[a]
the divergent synthesis of benzocycles are summarized The bidentate bisphosphine ligand (S,S)-Ph-BPE was
in Scheme 3c.
suitable for copper-allyl addition to a tethered ketone
to produce dihydronaphthalenol compounds, and
rendered the cyclization asymmetric. With NHC
ligands, such cyclization is not facile, leading to boro-
Conclusion
In conclusion, we developed copper-catalyzed chemo- allylation that produces indanols with high diastereo-
divergent intramolecular allyl addition of dienyl selectivity.
arenes with a tethered ketone group. By proper choice
of coordinating ligands under catalytic conditions,
allyl addition can be diverted to two different path-
ways, leading to five- and six-membered benzocycles
with high stereoselectivity from a single substrate.
Adv. Synth. Catal. 2021, 363, 1–8
4
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
Scheme 3. Mechanistic Investigations and Proposed Catalytic Cycles.
anhydrous THF (1 mL) was stirred for 10 min in a Schlenk tube
under an atmosphere of N2. A dienyl arene (1) (0.2 mmol)
dissolved in anhydrous THF (1.0 mL) was added to the reaction
mixture, followed by MeOH (0.2 mmol, 8 μL) and stirred for
6–24 h. Upon completion of the reaction indicated by TLC, the
reaction mixture was quenched with water. The aqueous layer
was extracted with ethyl acetate (3×10 mL). The combined
Experimental Section
General Procedure for the Synthesis of Indanol 2
(Scheme 2, Condition A)
A
mixture of IMesCuCl (0.01 mmol, 4.0 mg), LiOMe
(0.3 mmol, 11.4 mg) and B2pin2 (0.22 mmol, 55.8 mg) in
Adv. Synth. Catal. 2021, 363, 1–8
5
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
organic layers were dried over anhydrous MgSO4 and concen-
trated in vacuo. The crude residue was purified by silica gel
chromatography (EtOAc:Hexane=1:10).
Chem. Sci. 2020, 11, 11380–11393; d) Z. Liu, Y. Gao, T.
Zeng, K. M. Engle, Isr. J. Chem. 2020, 60, 219–229.
[5] For a review: a) G. J. P. Perry, T. Jia, D. J. Procter, ACS
Catal. 2020, 10, 1485–1499; For selected examples:;
b) Y. Sasaki, C. Zhong, M. Sawamura, H. Ito, J. Am.
Chem. Soc. 2010, 132, 1226–1227; c) L. Jiang, P. Cao,
M. Wang, B. Chen, B. Wang, J. Liao, Angew. Chem. Int.
Ed. 2016, 55, 13854–13858; Angew. Chem. 2016, 128,
14058–14062; d) Y.-Y. Gui, N. Hu, X.-W. Chen, L.-L.
Liao, T. Ju, J.-H. Ye, Z. Zhang, J. Li, D.-G. Yu, J. Am.
Chem. Soc. 2017, 139, 17011–17014; e) Y. Huang, K. B.
Smith, M. K. Brown, Angew. Chem. Int. Ed. 2017, 56,
13314–13318; Angew. Chem. 2017, 129, 13499–13503;
f) J.-J. Feng, M. Oestreich, Angew. Chem. Int. Ed. 2019,
58, 8211–8215; Angew. Chem. 2019, 131, 8295–8299.
[6] a) R. Sakae, K. Hirano, M. Miura, J. Am. Chem. Soc.
2015, 137, 6460–6463; b) W. Su, T.-J. Gong, X. Lu, M.-
Y. Xu, C.-G. Yu, Z.-Y. Xu, H.-Z. Yu, B. Xiao, Y. Fu,
Angew. Chem. Int. Ed. 2015, 54, 12957–12961; Angew.
Chem. 2015, 127, 13149–13153; c) W. Yuan, S. Ma, Adv.
Synth. Catal. 2012, 354, 1867–1872; d) R. Y. Liu, Y.
Yang, S. L. Buchwald, Angew. Chem. Int. Ed. 2016, 55,
14077–14080; Angew. Chem. 2016, 128, 14283–14286;
e) W. Su, T.-J. Gong, Q. Zhang, Q. Zhang, B. Xiao, Y.
Fu, ACS Catal. 2016, 6, 6417–6421.
General Procedure for the Synthesis of Dihydro-
naphthalenol 3 (Scheme2, Condition B)
A mixture of CuCl (0.01 mmol, 1.0 mg), NaOtBu (0.3 mmol,
28.8 mg), (S,S)-Ph-BPE (0.01 mmol, 5.1 mg) and B2pin2
(0.22 mmol, 55.8 mg) in anhydrous THF (1 mL) was stirred for
5 min in a Schlenk tube under an atmosphere of N2. A dienyl
arene (1) (0.2 mmol) dissolved in anhydrous THF (1.0 mL) was
added to the reaction mixture and stirred for 24 h. And then, to
the mixture was added sodium perborate tetrahydrate (3 equiv)
and THF:H2O (2 mL, 1:1). The reaction mixture was stirred for
overnight at room temperature. The reaction was quenched with
water and extracted with ethyl acetate (3×10 mL). The
combined organic layers were dried over MgSO4 and concen-
trated in vacuo. Pinacol was removed by dissolving the crude
mixture in MeOH:H2O (1:1), followed by concentration in
[18]
°
vacuo with 65 C water bath (usually 2–3 cycles). The crude
was purified by silica gel chromatography (EtOAc:Hexane=
1:2).
Acknowledgements
[7] a) T. Jia, Q. He, R. E. Ruscoe, A. P. Pulis, D. J. Procter,
Angew. Chem. Int. Ed. 2018, 57, 11305–11309; Angew.
Chem. 2018, 130, 11475–11479; b) T. Jia, M. J. Smith,
A. P. Pulis, G. J. P. Perry, J. Procter, ACS Catal. 2019, 9,
6744–6750; c) K. B. Smith, M. K. Brown, J. Am. Chem.
Soc. 2017, 139, 7721–7724; d) S. R. Sardini, M. K.
Brown, J. Am. Chem. Soc. 2017, 139, 9823–9826.
[8] a) D. Li, Y. Park, J. Yun, Org. Lett. 2018, 20, 7526–
7529; b) D. Li, Y. Park, W. Yoon, H. Yun, J. Yun, Org.
Lett. 2019, 21, 9699–9703; c) R. K. Acharyya, S. Kim,
Y. Park, J. T. Han, J. Yun, Org. Lett. 2020, 22, 7897–
7902.
This research has been supported by grants from the National
Research Foundation of Korea (NRF) (2019R1A2C2005706
and 2019R1A4A2001440).
References
[1] a) A. Kleeman, J. Engel, B. Kutscher, D. Reichert,
Pharmaceutical Substances; Thieme: New York, 2001;
b) D. J. Faulkner, Nat. Prod. Rep. 2002, 19, 1–48;
c) T. K. Devon, Handbook of Naturally Occurring
Compounds V1; Elsevier: Amsterdam, 2012.
[9] For reviews on borylative cyclizations: a) E. Buñuel,
D. J. Cárdenas, Eur. J. Org. Chem. 2016, 5446–5464;
b) Y. Ji, M. Zhang, M. Xing, H. Cui, Q. Zhao, C. Zhang,
Chin. J. Chem. 2021, 39, 391–401.
[10] T. Mita, M. Uchiyama, Y. Sato, Adv. Synth. Catal. 2020,
362, 1275–1280.
[2] a) I. Gallou, C. H. Senanayake, Chem. Rev. 2006, 106,
2843–2874; b) W. A. L. Otterlo, C. B. Koning, Chem.
Rev. 2009, 109, 3743–3782; c) J.-R. Chen, X.-Q. Hu, L.-
Q. Lu, W.-J. Xiao, Chem. Rev. 2015, 115, 5301–5365;
d) E. Aguilar, R. Sanz, M. A. Fernandez-Rodriguez, P.
Garcia-Garcia, Chem. Rev. 2016, 116, 8256–8311; e) X.-
D. An, J. Xiao, Org. Chem. Front. 2021, 8, 1364–1383.
[3] a) B. Baskar, H. J. Bae, S. E. An, J. Y. Cheong, Y. H.
Rhee, A. Duschek, S. F. Kirsch, Org. Lett. 2008, 10,
2605–2607; b) P. Sun, S. Gao, C. Yang, S. Guo, A. Lin,
H. Yao, Org. Lett. 2016, 18, 6464–6467; c) D. Ji, K. Liu,
J. Sun, Org. Lett. 2018, 20, 7708–7711; d) L.-C. Yang,
Y.-N. Wang, R. Liu, Y. Luo, X. Q. Ng, B. Yang, Z.-Q.
Rong, Y. Lan, Z. Shao, Y. Zhao, Nat. Chem. 2020, 12,
860–868.
[11] See the Supporting Information for the preparation of
compound 4a, 4-bromobenzoate of 3a. CCDC 2085917
(4a) contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre.
[12] See the Supporting Information Figure S3 for the
structural optimization of IMes-copper allyl intermediate
III.
[13] a) K. Semba, M. Shinomiya, T. Fujihara, J. Terao, Y.
Tsuji, Chem. Eur. J. 2013, 19, 7125–7132; b) S. Gao, M.
Wang, M. Chen, Org. Lett. 2018, 20, 7921–7925.
[14] Previously we reported that protoboration of 1-phenyl-
1,3-butadiene with IMesCu-Bpin resulted in the forma-
tion of the corresponding (Z)-allylboronate. See ref. 8a
and 8b.
[4] a) F. Wang, P. Chen, G. Liu, Acc. Chem. Res. 2018, 51,
2036–2046; b) D. Hemming, R. Fritzemeier, S. A. West-
cott, W. L. Santos, P. G. Steel, Chem. Soc. Rev. 2018, 47,
7477–7494; c) Q. Dherbassy, S. Manna, F. J. T. Talbot,
W. Prasitwatcharakorn, G. J. P. Perry, D. J. Procter,
Adv. Synth. Catal. 2021, 363, 1–8
6
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
asc.wiley-vch.de
[15] a) A. E. Walts, L. K. Hoong, W. R. Roush, J. Am. Chem. [17] For intermolecular copper-allyl additions to carbonyl:
Soc. 1985, 107, 8186–8190; b) M. A. Adam, A. E. Walts,
D. J. Harris, W. R. Roush, J. Am. Chem. Soc. 1986, 108,
3422–3434; c) S. R. Chemler, W. R. Roush, Recent
Applications of the Allylation Reaction to the Synthesis
of Natural Products. In Modern Carbonyl Chemistry;
(Eds.: J. Otera), Wiley-VCH: Weinheim, Germany, 2000;
pp 403–490.
a) M. Kanai, R. Wada, T. Shibuguchi, M. Shibasaki,
Pure Appl. Chem. 2008, 80, 1055–1062; b) F. Meng, H.
Jang, B. Jung, A. H. Hoveyda, Angew. Chem. Int. Ed.
2013, 52, 5046–5051; Angew. Chem. 2013, 125, 5150–
5155; c) B. Fu, X. Yuan, Y. Li, Y. Wang, Q. Zhang, T.
Xiong, Q. Zhang, Org. Lett. 2019, 21, 3576–3580; d) J.-
J. Feng, Y. Xu, M. Oestreich, Chem. Sci. 2019, 10, 9679–
9683; e) J. M. Zanghi, S. J. Meek, Angew. Chem. Int. Ed.
2020, 59, 8451–8455; Angew. Chem. 2020, 132, 8529–
8533.
[16] a) C. Li, R. Y. Liu, L. T. Jesikiewicz, Y. Yang, P. Liu,
S. L. Buchwald, J. Am. Chem. Soc. 2019, 141, 5062–
5070; b) C. Li, K. Shin, R. Y. Liu, S. L. Buchwald,
Angew. Chem. Int. Ed. 2019, 58, 17074–17080; Angew. [18] M. V. Joannou, B. S. Moyer, S. J. Meek, J. Am. Chem.
Chem. 2019, 131, 17230–17236.
Soc. 2015, 137, 6176–6179.
Adv. Synth. Catal. 2021, 363, 1–8
7
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

RESEARCH ARTICLE
Divergent Access to Benzocycles through Copper-Catalyzed
Borylative Cyclizations
Adv. Synth. Catal. 2021, 363, 1–8
W. S. Yoon, J. T. Han, J. Yun*