Copper-Catalyzed Enantioselective Ring-Opening of Cyclic Diaryliodoniums and O-Alkylhydroxylamines

Article abstract of DOI:10.1021/acs.orglett.9b02267

A preparation of 2-hydroxyamino-2′-iodobiaryls via the Cu-catalyzed enantioselective ring-opening reaction of cyclic diaryliodonium salts with O-alkylhydroxylamines is reported. 3,5-Di(tert-butyl)phenyl bis(oxazoline) was found to be the optimal ligand, a

Full text of DOI:10.1021/acs.orglett.9b02267

Letter
pubs.acs.org/OrgLett
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
Copper-Catalyzed Enantioselective Ring-Opening of Cyclic
Diaryliodoniums and O‑Alkylhydroxylamines
Qigang Li, Mingkai Zhang, Shuming Zhan, and Zhenhua Gu*
Department of Chemistry, Center for Excellence in Molecular Synthesis, and Hefei National Laboratory for Physical Sciences at the
Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, P. R. China
S
* Supporting Information
ABSTRACT: A preparation of 2-hydroxyamino-2′-iodobiaryls via the Cu-catalyzed enantioselective ring-opening reaction of
cyclic diaryliodonium salts with O-alkylhydroxylamines is reported. 3,5-Di(tert-butyl)phenyl bis(oxazoline) was found to be the
optimal ligand, and up to 99% ee values were achieved. The use of CaO as the base dramatically improved the yields and
inhibited the side reactions. Finally, synthetic applications of these hydroxylamines were briefly demonstrated.
dynamic equilibrium, the Akiyama and Wang groups realized
the dynamic kinetic resolution of biaryls via N,O-acetal
intermediates by either chiral phosphoric acid or chiral iridium
catalysis.10 In 2002, Hayashi and coworkers demonstrated a
Ni-catalyzed asymmetric C−S bond cleavage/ring-opening
reaction of dibenzo[b,d]thiophenes (Scheme 1b).11 Later on,
the same group studied a palladium-catalyzed ring-opening of
cyclic diaryliodonium, where they showed one example for an
asymmetric trial with 38% yield and 28% ee (Scheme 2a).12,13
Recently, Gu and coworkers realized the Cu-catalyzed highly
enantioselective ring-opening amination, thiolation, and oxy-
genation reactions of cyclic diaryliodonium (Scheme 2b).14
More than 1 year later, Zhang and coworkers reported a very
ince the observation of “non-free rotation” of 6,6′-
1
Sdinitrodiphenic acid by Christie and Kenner,
axial
chirality as a new stereogenic element has come to the
attention of chemists and later on became one of the privileged
chiral units of chiral ligands and catalysts in asymmetric
catalysis. Furthermore, mastigophorene, vancomycin, blumea-
nine, and other related natural products containing axially
chiral biaryl units were isolated.2
The applications of biaryl axial chirality in asymmetric
catalysis and its existence in biological active molecules urged
chemists to develop new practical methods to access these
highly valuable scaffolds. Besides the aryl−aryl cross-coupling3
and oxidative couplings,4 elegant methods including de novo
asymmetric aryl ring construction,5 desymmetrization or
resolution,6 as well as point-to-axial chirality transfer7 have
been developed for the diverse preparation of optically active
atropisomers. Recently, organo-catalysis became a robust
method for the atropisomers syntheses.8 The asymmetric
ring-opening of Bringmann’s lactones, which undergo fast
dynamic equilibrium of their (R)- and (S)-isomers, is a very
powerful strategy in the construction of axially chiral
compounds (Scheme 1a).9 Remarkably, inspired by this fast
Scheme 2. Transition-Metal-Catalyzed Asymmetric Ring-
Opening of Cyclic Diaryliodoniums
Scheme 1. Asymmetric Ring-Opening Reactions
Received: July 2, 2019
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.9b02267
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
similar example of Cu-catalyzed asymmetric acyloxylation with
cyclic diaryliodoniums (Scheme 2b).15
H2O in the reaction system, CaO was employed as the base.
Pleasingly, the reaction became much cleaner, and a drastic
increase in yield was achieved, along with satisfactory
stereoselectivity (entry 4). The enantioselectivity ranged
from 35 to 72% with bis(oxazoline) L2−L4 as the ligands
(entries 5−7). Screening the ligand L5 or spirobis(oxazo1ine)
L6−L8 showed that only L7 gave comparable stereoselectivity
to L1 (entries 8−11). Further optimization focused on the
modification on the aryl ring of bis(oxazoline). With 3,5-
dimethylphenyl-substituted ligand L9, compound 3a was
formed in 95% ee (entry 12). A continued increase in the
steric size of the aryl ring (L10) further improved the
stereoinduction, and the ee value jumped to 99% (entry 13).
Moreover, decreasing the loading of Cu(OTf)2 to 5 mol % did
not affect the overall outcome of this transformation (entry
14). The absolute configuration of 3a was determined by
single-crystal X-ray diffraction analysis (CCDC 1921712).
With the optimal conditions in hand, the substrate scope of
this amination reaction was tested (Scheme 3). The para
Notably, in the Cu-catalyzed asymmetric amination reaction,
only the primary amine afforded high enantioselectivity. The
secondary amines, including dialkyl amines or N-alkyl anilines,
gave dramatically decreased ee values. Moreover, until now,
trifluoromethanesulfonamide was the only amide that could be
applied in this ring-opening reaction, with low conversion and
reasonable enantioselectivity. Furthermore, the use of
ammonia as the nucleophile was unsuccessful. In consideration
of the strong derivatization capability of hydroxyamines, we
report a Cu-catalyzed highly enantioselective ring-opening/
amination of cyclic diaryliodoniums with O-alkylhydroxyl-
amines (Scheme 2c).
We started our investigation by using diaryliodonium 1a and
N-methoxy-4-methylbenzenesulfonamide 2a as the model
substrates. With Na2CO3 as the base and Ph-Box L1 as the
ligand, the reaction afforded a complicated mixture, and the
desired product 3a was isolated in only 3% yield (Table 1,
a
a
Table 1. Reaction Condition Optimization
Scheme 3. Substrate Scope
entry
ligand
base
yield (%)
ee (%)
1
2
3
4
5
6
7
8
L1
L1
L1
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
L10
Na2CO3
K2CO3
CaCO3
CaO
CaO
CaO
CaO
CaO
CaO
CaO
3
91 (S)
72 (S)
17
N.R.
83
85
86
99
88
92
91
92
97
99
99
94 (S)
66 (R)
35 (S)
72 (R)
3 (S)
81 (S)
90 (S)
70 (S)
95 (S)
99 (S)
99 (S)
9
10
11
12
13
CaO
CaO
CaO
CaO
b
14
a
Unless otherwise stated, the reaction was conducted with 1a (0.10
a
mmol), 2a (0.12 mmol, 1.2 equiv), Cu(OTf)2 (0.010 mmol, 10 mol
Reaction was conducted with 1 (0.10 mmol), O-alkylhydroxylamines
%), Ligand (1.2 equiv to Cu), and base (3.0 equiv) in (CH2Cl)2 (2.0
mL) at rt for 24 h. 5 mol % of Cu(OTf)2, 7.5 mol % of L10 and
CaO (2.0 equiv) were used.
2 (0.12 mmol, 1.2 equiv), Cu(OTf)2 (0.0050 mmol, 5.0 mol %), L10
(0.0075 mmol, 7.5 mol %), and CaO powder (0.20 mmol, 2.0 equiv)
in 1,2-dichloroethane (2.0 mL) at rt for 12 h.
b
entry 1). With the use of K2CO3 in lieu of Na2CO3, an
improved yield of 3a was achieved, while the ee value dropped
(entry 2). Disappointedly, replacing K2CO3 with CaCO3 did
not give the desired product (entry 3). During the
investigation, one of the byproducts was characterized as 2′-
iodo-6,6′-dimethyl-[1,1′-biphenyl]-2-ol, which was formed
with H2O as the nucleophile. To remove a trace amount of
substituents on the benzenesulfonamide moiety had little effect
on the yield or stereoselectivity. For instance, compounds 3b−
d were formed in almost quantitative yield with 99% ee. 2-
Chloro-N-methoxybenzenesulfonamide resulted in decreases
in both yield and enantioselectivity (3e). 2,4,6-Trimethyl-
phenyl and β-naphthyl sulphonamides smoothly coupled to 1a
to lead to 3f and 3g in high stereoselectivity. O-alkylhydroxyl-
B
DOI: 10.1021/acs.orglett.9b02267
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
Accession Codes
amines with N-methanesulfonyl, N-Cbz, or N-Boc protecting
groups were also compatible substrates, and 96, 93, and 95% ee
were achieved, respectively (3h−j). Subsequently, the
reactivity by variation of the substituents on the oxygen
atom was also investigated. Product 3k with an O-allyl
substituent was formed with 74% ee; however, high stereo-
induction was still achieved for the O-Bn and O-PMB products
(3l and 3m). In a further experiment, the substituent effect on
the diaryliodonium salts was studies. The reactions proceeded
uneventfully with 5,5′-dimethyl-, 4,4′-dimethyl-, and 5,5′-
difluoro-substituted diaryliodoniums (3n−r). Likewise, bi-
naphthyl skeletons successfully underwent this Cu-catalyzed
ring-opening reaction with a slight decrease in the yield (3s).
For the nonsymmetric diaryliodonium, introducing an adjacent
group (i.e., methyl) to the C−I bond was necessary for high
regioselectivity. For instance, 3t was isolated as a single
regioisomer in 93% yield with 95% ee.
CCDC 1921712 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: zhgu@ustc.edu.cn
ORCID
Zhenhua Gu: 0000-0001-8168-2012
Notes
The authors declare no competing financial interest.
The utility of these products was further demonstrated by
the modification of hydroxylamine functionality (Scheme 4).
ACKNOWLEDGMENTS
■
We are grateful for financial supported from NSFC (21622206,
21871241), the Fundamental Research Funds for the Central
Universities (WK2060190086).
Scheme 4. Synthetic Applications
REFERENCES
■
(1) Christie, G. H.; Kenner, J. The Molecular Configurations of
Polynuclear Aromatic Compounds. Part I. The Resolution of γ-6:6’-
Dinitro- and 4:6:4’6’-Tetranitro-diphenic Acid into Optically Active
Components. J. Chem. Soc., Trans. 1922, 121, 614−620.
(2) (a) Bringmann, G.; Gulder, T.; Gulder, T. A. M.; Breuning, M.
Atroposelective Total Synthesis of Axially Chiral Biaryl Natural
Products. Chem. Rev. 2011, 111, 563−639. (b) Clayden, J.; Moran, W.
J.; Edwards, P. J.; LaPlante, S. R. The Challenges of Atropisomerism
in Drug Discovery. Angew. Chem., Int. Ed. 2009, 48, 6398−6401.
(3) (a) Hayashi, T.; Hayashizaki, K.; Kiyoi, T.; Ito, Y. Asymmetric
Synthesis Catalyzed by Chiral Ferrocenylphosphine-transition-metal
Complexes. 6. Practical Asymmetric Synthesis of 1,1’-Binaphthyls via
Asymmetric Cross-coupling with a Chiral [(Alkoxyalkyl) Ferrocenyl]
Monophosphine/Nickel Catalyst. J. Am. Chem. Soc. 1988, 110, 8153−
8156. (b) Genov, M.; Almorín, A.; Espinet, P. Efficient Synthesis of
Chiral 1,1’-Binaphthalenes by the Asymmetric Suzuki−Miyaura
Reaction: Dramatic Synthetic Improvement by Simple Purification
of Naphthylboronic Acids. Chem. - Eur. J. 2006, 12, 9346−9352.
(c) Wang, S.; Li, J.; Miao, T.; Wu, W.; Li, Q.; Zhuang, Y.; Zhou, Z.;
Qiu, L. Highly Efficient Synthesis of a Class of Novel Chiral-Bridged
Atropisomeric Monophosphine Ligands via Simple Desymmetrization
and Their Applications in Asymmetric Suzuki−Miyaura Coupling
Reaction. Org. Lett. 2012, 14, 1966−1969. (d) Uozumi, Y.; Matsuura,
Y.; Arakawa, T.; Yamada, Y. M. A. Asymmetric Suzuki−Miyaura
Coupling in Water with a Chiral Palladium Catalyst Supported on an
Amphiphilic Resin. Angew. Chem., Int. Ed. 2009, 48, 2708−2710.
(e) Bermejo, A.; Ros, A.; Fernandez, R.; Lassaletta, J. M. C2-
Symmetric Bis-Hydrazones as Ligands in the Asymmetric Suzuki−
Miyaura Cross-Coupling. J. Am. Chem. Soc. 2008, 130, 15798−15799.
(f) Shen, X.; Jones, G. O.; Watson, D. A.; Bhayana, B.; Buchwald, S. L.
Enantioselective Synthesis of Axially Chiral Biaryls by the Pd-
catalyzed Suzuki-Miyaura reaction: Substrate Scope and Quantum
Mechanical Investigations. J. Am. Chem. Soc. 2010, 132, 11278−
11287. (g) Xu, G.; Fu, W.; Liu, G.; Senanayake, C. H.; Tang, W.
Efficient Syntheses of Korupensamines A, B and Michellamine B by
Asymmetric Suzuki-Miyaura Coupling Reactions. J. Am. Chem. Soc.
2014, 136, 570−573. (h) Feng, J.; Li, B.; He, Y.; Gu, Z.
Enantioselective Synthesis of Atropisomeric Vinyl Arene Compounds
by Palladium Catalysis: A Carbene Strategy. Angew. Chem., Int. Ed.
2016, 55, 2186−2190. (i) Pan, C.; Zhu, Z.; Zhang, M.; Gu, Z.
Palladium-Catalyzed Enantioselective Synthesis of 2-Aryl Cyclohex-2-
enone Atropisomers: Platform Molecules for the Divergent Synthesis
Heating 3a in CH3NO2 at 120 °C resulted in N−O bond
selective cleavage to afford 4a in 71% yield without losing the
enantiopurity (eq 1). The chemoselective removal of the tert-
butyloxycarbonyl (Boc) group proceeded uneventfully upon
the treatment of 3j with AlCl3 in THF (eq 2). However, when
CH3SSCH3 in lieu of THF was used as the solvent, primary
amine 6j, along with Friedel−Crafts thiolation product 7j were
isolated in 32 and 34% yield, respectively (eq 3).16
In summary, we have developed a Cu-catalyzed asymmetric
ring-opening of cyclic diaryliodonium salts and O-alkylhydrox-
ylamines. The base CaO played a pivotal role in the inhibition
of the side reactions to get a high yield, and the ligand 3,5-
di(tert-butyl)phenyl bis(oxazoline) showed the best stereo-
induction. The products were readily manipulated to lead to
aniline analogues with different degrees of substitution.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.or-
glett.9b02267.
Experimental procedures, characterization of products,
and spectroscopic data (PDF)
C
DOI: 10.1021/acs.orglett.9b02267
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
of Axially Chiral Biaryl Compounds. Angew. Chem., Int. Ed. 2017, 56,
4777−4781.
Traceless Central-to-Axial Chirality Exchange. J. Am. Chem. Soc.
2011, 133, 18−20.
(4) (a) Li, X.; Yang, J.; Kozlowski, M. C. Enantioselective Oxidative
Biaryl Coupling Reactions Catalyzed by 1,5-Diazadecalin Metal
Complexes. Org. Lett. 2001, 3, 1137−1140. (b) Luo, Z.; Liu, Q.;
Gong, L.; Cui, X.; Mi, A.; Jiang, Y. The Rational Design of Novel
Chiral Oxovanadium(IV) Complexes for Highly Enantioselective
Oxidative Coupling of 2-Naphthols. Chem. Commun. 2002, 914−915.
(c) Luo, Z.; Liu, Q.; Gong, L.; Cui, X.; Mi, A.; Jiang, Y. Novel Achiral
Biphenol-Derived Diastereomeric Oxovanadium(IV) Complexes for
Highly Enantioselective Oxidative Coupling of 2-Naphthols. Angew.
Chem., Int. Ed. 2002, 41, 4532−4535. (d) Mulrooney, C. A.; Li, X.;
DiVirgilio, E. S.; Kozlowski, M. C. General Approach for the Synthesis
of Chiral Perylenequinones via Catalytic Enantioselective Oxidative
Biaryl Coupling. J. Am. Chem. Soc. 2003, 125, 6856−6857. (e) Egami,
H.; Katsuki, T. Iron-Catalyzed Asymmetric Aerobic Oxidation:
Oxidative Coupling of 2-Naphthols. J. Am. Chem. Soc. 2009, 131,
6082−6083.
(8) (a) Chen, Y.; Cheng, D.; Zhang, J.; Wang, Y.; Liu, X.; Tan, B.
Atroposelective Synthesis of Axially Chiral Biaryldiols via Organo-
catalytic Arylation of 2-Naphthols. J. Am. Chem. Soc. 2015, 137,
15062−15065. (b) Zhang, H.; Wang, C.; Li, C.; Mei, G.; Li, Y.; Shi, F.
Design and Enantioselective Construction of Axially Chiral Naphthyl-
Indole Skeletons. Angew. Chem., Int. Ed. 2017, 56, 116−121. (c) Yu,
C.; Huang, H.; Li, X.; Zhang, Y.; Wang, W. Dynamic Kinetic
Resolution of Biaryl Lactones via a Chiral Bifunctional Amine
Thiourea-Catalyzed Highly Atropo-enantioselective Transesterifica-
tion. J. Am. Chem. Soc. 2016, 138, 6956−6959. (d) Li, G.; Gao, H.;
Keene, C.; Devonas, M.; Ess, D. H.; Kurti, L. Organocatalytic Aryl−
̈
Aryl Bond Formation: An Atroposelective [3,3]-Rearrangement
Approach to BINAM Derivatives. J. Am. Chem. Soc. 2013, 135,
7414−7417. (e) Wang, Y. B.; Tan, B. Construction of Axially Chiral
Compounds via Asymmetric Organocatalysis. Acc. Chem. Res. 2018,
51, 534−547 and references therein. .
(9) (a) Bringmann, G.; Breuning, M.; Tasler, S. The Lactone
Concept: An Efficient Pathway to Axially Chiral Natural Products and
Useful Reagents. Synthesis 1999, 1999, 525−558. (b) Bringmann, G.;
Menche, D. Stereoselective Total Synthesis of Axially Chiral Natural
Products via Biaryl Lactones. Acc. Chem. Res. 2001, 34, 615−624.
(c) Chen, G. Q.; Lin, B. J.; Huang, J. M.; Zhao, L. Y.; Chen, Q. S.; Jia,
S. P.; Yin, Q.; Zhang, X. Design and Synthesis of Chiral
Oxaspirocyclic Ligands for Ir-catalyzed Direct Asymmetric Reduction
of Bringmann’s Lactones with Molecular H2. J. Am. Chem. Soc. 2018,
140, 8064−8068.
(10) (a) Mori, K.; Itakura, T.; Akiyama, T. Enantiodivergent
Atroposelective Synthesis of Chiral Biaryls by Asymmetric Transfer
Hydrogenation: Chiral Phosphoric Acid Catalyzed Dynamic Kinetic
Resolution. Angew. Chem., Int. Ed. 2016, 55, 11642−11646.
(b) Zhang, J.; Wang, J. Atropoenantioselective Redox-Neutral
Amination of Biaryl Compounds through Borrowing Hydrogen and
Dynamic Kinetic Resolution. Angew. Chem., Int. Ed. 2018, 57, 465−
469.
(11) Shimada, T.; Cho, Y. H.; Hayashi, T. Nickel-Catalyzed
Asymmetric Grignard Cross-Coupling of Dinaphthothiophene Giving
Axially Chiral 1,1’-Binaphthyls. J. Am. Chem. Soc. 2002, 124, 13396−
13397.
(12) Kina, A.; Miki, H.; Cho, Y.-H.; Hayashi, T. Palladium-
Catalyzed Heck and Carbonyl Reactions of a Dinaphthaleneiodonium
Salts Forming Functionalized 2-Iodo-1,1’-binaphthyls. Adv. Synth.
Catal. 2004, 346, 1728−1732.
(13) Merritt, E. A.; Olofsson, B. Diaryliodonium Salts: A Journey
from Obscurity to Fame. Angew. Chem., Int. Ed. 2009, 48, 9052−9070.
(14) (a) Zhao, K.; Duan, L.; Xu, S.; Jiang, J.; Fu, Y.; Gu, Z.
Enhanced Reactivity by Torsional Strain of Cyclic Diaryliodonium in
Cu-Catalyzed Enantioselective Ring-Opening Reaction. Chem 2018,
4, 599−612. (b) Xu, S.; Zhao, K.; Gu, Z. Copper-Catalyzed
Asymmetric Ring-opening of Cyclic Diaryliodonium with Benzyl
and Aliphatic Amines. Adv. Synth. Catal. 2018, 360, 3877−3883.
(c) Hou, M.; Deng, R.; Gu, Z. Cu-Catalyzed Enantioselective
Atropisomer Synthesis via Thiolative Ring Opening of Five-
Membered Cyclic Diaryliodoniums. Org. Lett. 2018, 20, 5779−
5783. (d) Xue, X.; Gu, Z. Synthesis of Bridged Biaryl Atropisomers
via Sequential Cu- and Pd-Catalyzed Asymmetric Ring Opening and
Cyclization. Org. Lett. 2019, 21, 3942−4945.
(15) Zhu, K.; Xu, K.; Fang, Q.; Wang, Y.; Tang, B.; Zhang, F.
Enantioselective Synthesis of Axially Chiral Biaryls via Cu-Catalyzed
Acyloxylation of Cyclic Diaryliodonium Salts. ACS Catal. 2019, 9,
4951−4957.
(16) Matsumoto, K.; Kato, M.; Sakamoto, T.; Kikugawa, Y. A Direct
Aromatic Methylsulfanylation of N-Aryl-N-Methoxyacetamides with
an Aluminum Chloride-Dimethyl Sulfide System. J. Chem. Res., Synop.
1995, 1, 34−35.
(5) (a) Gutnov, A.; Heller, B.; Fischer, C.; Drexler, H. J.;
Spannenberg, A.; Sundermann, B.; Sundermann, C. Cobalt(I)-
Catalyzed Asymmetric [2+2+2] Cycloaddition of Alkynes and
Nitriles: Synthesis of Enantiomerically Enriched Atropoisomers of
2-Arylpyridines. Angew. Chem., Int. Ed. 2004, 43, 3795−3797.
(b) Tanaka, K.; Nishida, G.; Wada, A.; Noguchi, K. Enantioselective
Synthesis of Axially Chiral Phthalides through Cationic [RhI(H8-
binap)]-Catalyzed Cross Alkyne Cyclotrimerization. Angew. Chem.,
Int. Ed. 2004, 43, 6510−6512. (c) Shibata, T.; Fujimoto, T.; Yokota,
K.; Takagi, K. Iridium Complex-Catalyzed Highly Enantio- and
Diastereoselective [2+2+2] Cycloaddition for the Synthesis of Axially
Chiral Teraryl Compounds. J. Am. Chem. Soc. 2004, 126, 8382−8383.
(d) Mori, F.; Fukawa, N.; Noguchi, K.; Tanaka, K. Asymmetric
Synthesis of Axially Chiral Biaryl Diphosphine Ligands by Rhodium-
Catalyzed Enantioselective Intramolecular Double [2+2+2] Cyclo-
addition. Org. Lett. 2011, 13, 362−365. (e) Auge, M.; Feraldi-Xypolia,
A.; Barbazanges, M.; Aubert, C.; Fensterbank, L.; Gandon, V.;
Kolodziej, E.; Ollivier, C. Double-Stereodifferentiation in Rhodium-
Catalyzed [2+2+2] Cycloaddition: Chiral Ligand/Chiral Counterion
Matched Pair. Org. Lett. 2015, 17, 3754−3757.
́
́
(6) (a) Ros, A.; Estepa, B.; Ramírez-Lopez, P.; Alvarez, E.;
́
Fernandez, R.; Lassaletta, J. M. Dynamic Kinetic Cross-coupling
Strategy for the Asymmetric Synthesis of Axially Chiral Heterobiaryls.
J. Am. Chem. Soc. 2013, 135, 15730−15733. (b) Bhat, V.; Wang, S.;
Stoltz, B. M.; Virgil, S. C. Asymmetric Synthesis of Quinap via
Dynamic Kinetic Resolution. J. Am. Chem. Soc. 2013, 135, 16829−
16832. (c) Zheng, J.; You, S. L. Construction of Axial Chirality by
Rhodium-catalyzed Asymmetric Dehydrogenative Heck Coupling of
Biaryl Compounds with Alkenes. Angew. Chem., Int. Ed. 2014, 53,
13244−13247. (d) Wang, J.; Chen, M. W.; Ji, Y.; Hu, S. B.; Zhou, Y.
G. Kinetic Resolution of Axially Chiral 5- or 8-Substituted Quinilines
via Asymmetric Transfer Hydrogenation. J. Am. Chem. Soc. 2016, 138,
10413−10416. (e) Yao, Q. J.; Zhang, S.; Zhan, B. B.; Shi, B. F.
Atroposelective Synthesis of Axially Chiral Biaryls by Palladium-
catalyzed Asymmetric C-H Olefination Enabled by a Transient Chiral
Auxiliary. Angew. Chem., Int. Ed. 2017, 56, 6617−6621. (f) Luo, J.;
Zhang, T.; Wang, L.; Liao, G.; Yao, Q.; Wu, Y. J.; Zhan, B.-B.; Lan, Y.;
Lin, X.-F.; Shi, B.-F. Enantioselective Synthesis of Biaryl Atropisomers
by Pd-Catalyzed C−H Olefination using Chiral Spiro Phosphoric
Acid Ligands. Angew. Chem., Int. Ed. 2019, 58, 6708−6712. (g) Wang,
Q.; Cai, Z.-J.; Liu, C.-X.; Gu, Q.; You, S.-L. Rhodium-Catalyzed
Atroposelective C−H Arylation: Efficient Synthesis of Axially Chiral
Heterobiaryls. J. Am. Chem. Soc. 2019, 141, 9504−9510. (h) Deng, R.;
Xi, J.; Li, Q.; Gu, Z. Enantioselective Carbon-Carbon Bond Cleavage
for Biaryl Atropisomers Synthesis. Chem 2019, 5, 1834.
(7) (a) Nishii, Y.; Wakasugi, K.; Koga, K.; Tanabe, Y. Chirality
Exchange from sp3 Central Chirality to Axial Chirality: Benzannu-
lation of Optically Active Diaryl-2,2-dichlorocyclopropylmethanols to
Axially Chiral α-Arylnaphthalenes. J. Am. Chem. Soc. 2004, 126,
5358−5359. (b) Guo, F.; Konkol, L. C.; Thomson, R. J.
Enantioselective Synthesis of Biphenols from 1,4-Diketones by
D
DOI: 10.1021/acs.orglett.9b02267
Org. Lett. XXXX, XXX, XXX−XXX