Synthesis of structurally diversified BINOLs and NOBINs via palladium-catalyzed C-H arylation with diazoquinones

Article abstract of DOI:10.1007/s11426-021-1003-9

Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under one set of reaction conditions. The judicious selection of palladium-catalytic system plays a pivotal role in the excellent selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthylamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromo-substituents which cannot survive in conventional palladium-catalyzed reactions were well-compatible with this set of conditions, providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis. [Figure not available: see fulltext.].

Full text of DOI:10.1007/s11426-021-1003-9

SCIENCE CHINA
Chemistry
•ARTICLES•
https://doi.org/10.1007/s11426-021-1003-9
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Synthesis of structurally diversified BINOLs and NOBINs via
palladium-catalyzed C–H arylation with diazoquinones
Ji-Wei Zhang1,2†, Fei Jiang2†, Ye-Hui Chen2†, Shao-Hua Xiang2,3 & Bin Tan2*
1School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China;
2Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China;
3Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
Received March 25, 2021; accepted April 2, 2021; published online June 23, 2021
Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under
one set of reaction conditions. The judicious selection of palladium catalytic system plays a pivotal role in the excellent
selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthy-
lamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromo sub-
stituent which cannot be survived in conventional palladium catalyzed reactions were well-compatible with this set of conditions,
providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric
variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis.
BINOLs, NOBINs, high selectivity, C–H arylation, palladium-catalysis
Citation:
Zhang JW, Jiang F, Chen YH, Xiang SH, Tan B. Synthesis of structurally diversified BINOLs and NOBINs via palladium-catalyzed C–H arylation
with diazoquinones. Sci China Chem, 2021, 64, https://doi.org/10.1007/s11426-021-1003-9
1 Introduction
Meanwhile, the potential of the oxidative dehydrogenative or
the reductive dehalogenation cross-coupling of two aryl
counterparts was restricted by the confined substrate gen-
erality and poor chemoselectivity [3]. Accordingly, a direct
and universal approach to access BINOL and NOBIN deri-
vatives, ideally from only one type of arylation reagents,
remained highly desirable. In this context, quinones as well
as iminoquinones were elegantly exploited as a class of
convenient pre-oxidized surrogates towards the biaryl atro-
pisomers possessing a phenol moiety. Undoubtedly, this
discovery provided an efficient solution to acquire both
biaryldiols [4], and biaryl amino alcohols [5], particularly
with asymmetric aryl structures. Nonetheless, the extension
to the synthesis of biaryls with BINOL and NOBIN scaffolds
was rarely involved. Following this line, diarylhalonium
salts were then employed by our group as efficient naph-
thylation reagents for the reaction with naphthylhydrox-
ylamines to construct NOBIN derivatives [6]. However,
1,1′-Bi-2-naphthol (BINOL) and 2-amino-2′-hydroxy-1,1′-
binaphthyl (NOBIN) constituting the core structure of var-
ious axially chiral biaryls are widely applied in asymmetric
transformations as chiral ligands or organocatalysts [1].
The significance of such backbones is further illustrated by
their prevalence in natural products, biologically active
molecules and functional materials (Scheme 1(a)) [2]. Given
the well-explored resolution methods, the synthesis of ra-
cemic BINOLs and NOBINs attracted extensive attention in
recent years. Conventional coupling between arylboronic
acid and aryl halides under transition metal catalysis ne-
cessitated the tedious pre-functionalization of both arenes
and then seriously influenced the reaction efficiency.
†These authors contributed equally to this work.
*Corresponding author (email: tanb@sustech.edu.cn)
© Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2021
chem.scichina.com link.springer.com

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Zhang et al. Sci China Chem
Scheme 1 (a) Selected applications of the molecules carrying BINOL or NOBIN backbone; (b) our strategies for highly selective synthesis of BINOL and
NOBIN derivatives via direct C–H arylation with 1-DNQs under transition metal catalysis (color online).
BINOL and its derivatives remained untouchable through
this approach. Considering the importance of both BINOLs
and NOBINs, the exploration of more versatile aryl partners
is still necessary.
with unmasking phenols, we initiated our studies on the
expedite synthesis of the most representative biaryl atropi-
somers, BINOLs and NOBINs, from one type of substrates
1-DNQs (Scheme 1(b)).
On the other hand, diazo quinones have received increas-
ing attention because of their application in C–H arylation
reactions under transition metal catalysis recently. A series of
biaryl compounds have been effectively assembled through
the carbene transfer process with arene substrates containing
directing group or electron-rich arenes [7]. Based on these
achievements and our continuous research interest in con-
structing biaryl atropisomers [8], we envisaged that 1-diazo-
2-naphthoquinones (1-DNQs) might be competent arylation
candidates for coupling with both 2-naphthol and 2-
naphthylamine to afford the desired BINOL, NOBIN and
their derivatives. However, the major challenge in this sce-
nario would be the chemoselectivity issue that originated
from the competitive X–H (X=N or O) bond insertion, which
has been clearly revealed in the previous investigations [9].
Additionally, it was found that satisfactory results were only
obtained for the arenes carrying a single reactive site for
most cases. Inspired by the exquisite work by Zhang’s group
[10] on the catalyst-controlled site-selective C–H arylation
2 Experimental
Under an argon atmosphere, an oven-dried Schlenk tube
equipped with a magnetic stir bar was charged with 1 or 5
(0.20 mmol), 2 and Pd(OAc)2. Anhydrous dichloromethane
(DCM) (2 mL) was added and the reaction mixture was
stirred for 36 h at room temperature till 1 or 5 was com-
pletely consumed (monitored by thin layer chromatography
(TLC)). After evaporating the solvent, the residue was pur-
ified by flash chromatography to afford the corresponding
product 3 or 6. The details are listed in the Supporting in-
formation online.
3 Results and discussion
Our investigation was commenced with the reaction of 1-
DNQ 2a and 2-naphthol 1a with commonly used catalyst

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Zhang et al. Sci China Chem
Table 1 Optimization of the reaction conditions (color online)
a)
b)
b)
Entry
1
2d)
Solvent
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCE
Cat.
Rh2(OAc)4
Fe(ClO4)2
CuCl2
3a/4a
1/12
–
Yield (%)
82c)
trace
trace
trace
41
3
–
4
AgOTf
–
5d)
6d)
7
IPrAuCle)
[Cp*IrCl2]2
Pd(OAc)2
Pd(TFA)2
PdCl2
[(η3-C3H5)PdCl]2
Pd2(dba)3
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
9/1
4/1
19
12/1
11/1
10/1
11/1
9/1
87
8
81
9
82
10
11
12
13
14
15f)
83
60
11/1
10/1
10/1
12/1
83
toluene
EtOAc
DCM
66
80
93 (92)g)
a) Unless otherwise specified, reactions were performed with 1a (0.10 mmol), 2a (0.10 mmol) and Cat. (5 mol%) in solvent (1.0 mL) at room temperature
1
for 36 h. b) Yield of 3a and the ratio of 3a/4a were determined by H NMR analysis of the crude reaction mixture using 1,3,5-trimethoxybenzene as the
internal standard. c) Yield of 4a. d) Reaction was performed at 80 °C with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF, 6 mol%) as the
additive. e) IPr=1,3-bis(2,6-di-ipropyl-phenyl)imidazol-2-ylidene. f) Pd(OAc)2 (3 mol%) was used with 1a/2a=1/1.2. g) Reaction was performed at
0.20 mmol scale, isolated yield.
Rh2(OAc)4 (5 mol%) in dichloromethane at room tempera-
ture. Unsurprisingly, the O–H bond insertion product 4a
dominated the reaction system after 36 h and less than 10%
of the target product 3a was detected (Table 1, entry 1).
Following examination of other reported conditions for the
reaction with 1-DNQs met with failure (entries 2–6), although
Ir(III) and Au(I) dramatically increase the proportion of 3a in
the mixture under elevated temperature with NaBArF4. De-
lightfully, the formation of the competitive O–H insertion
product 4a could be effectively inhibited when Pd(OAc)2
was utilized as catalyst (entry 7). Other screened Pd(II)
catalysts also gave 3a in about 80% yield with more than
10:1 ratio of 3a:4a (entries 8–10), while the use of Pd(0) led
to slight erosion on both chemical yield and chemoselectivity
(entry 11). With Pd(OAc)2 as the superior catalyst, the next
optimization through the evaluation of various solvents
proved DCM as the best solvent. Finally, the optimal results
were obtained with a 92% isolated yield of 3a and 12:1 ratio
of 3a:4a through fine-tuned stoichiometry of reactants and
catalyst loading (entry 15).
naphthol substrates were completely transformed within 36 h
and afforded the respective non-C2 symmetric BINOLs in
generally good efficiency with the recorded yield up to 94%
(3b–3o). The electronic property of the substituents as well
as the substitution patterns exerted limited influence on the
reaction results. Notably, 2-naphthols possessing a sterically
bulky group at the C3 position was also amendable to give
the desired product in good yields (3l–3m). In addition, the
bromo substituent which cannot be survived in conventional
palladium catalyzed reactions was well-tolerated for this set
of conditions, offering an efficient handle for further trans-
formations (3d, 3g, 3j and 3n).
Subsequently, the generality of 1-DNQs 2 was evaluated.
First, the reaction of 1-DNQs 2 and model 2-naphthol 1a was
performed and the desired BINOLs were obtained in 72%–
85% yields (3d, 3g and 3p–3q). It should be noted that 3d
and 3g were also formed effectively via the reverse of cou-
pling partner. Following examination on 1-DNQs revealed
that the electronic nature and position of the substituents
imposed a negligible effect on the reaction efficiency and a
wide range of C2 symmetric and non-C2 symmetric BINOLs
were synthesized in up to 89% yield through the selection of
coupling partners (3r–3ak). A variety of functional groups
With the optimized conditions in hand, the generality of
this transformation was then firstly explored with respect to
2-naphthols 1. As illustrated in Table 2, all these examined 2-

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Zhang et al. Sci China Chem
a),b)
Table 2 Substrate scope of 2-naphthols and 1-DNQs
(color online)
a) Unless otherwise specified, reactions were performed with 1a (0.20 mmol), 2a (0.24 mmol) and Pd(OAc)2 (3 mol%) in DCM (2.0 mL) at room
temperature for 36 h; b) isolated yield; c) trip=2,4,6-triisopropyl-C6H2.
including phenyl, 2-naphthyl and bromo were well compa-
tible for this reaction, similarly. Noteworthy, 1-DNQ with an
extended fused ring system was also an efficient substrate
and the reactions with different 2-naphthols could produce
the corresponding BINOLs in about 80% yield (3q and 3ah–
3ak). Moreover, C2 symmetric 3,3′-diaryl BINOLs (3af–
3ag) which have been recognized as the preferred backbone
of various ligands were obtained in synthetically useful yields.
Successful establishment of a highly efficient and selective
approach to construct BINOLs encouraged us to explore the
feasibility of procuring NOBINs, another type of privileged
biaryl atropisomers, to further extend the applicability of the
developed method. As compared with 2-naphthol, the reac-
tion with 2-naphthylamine was considered to be more chal-

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Zhang et al. Sci China Chem
a),b)
Table 3 The substrate scope of N-Boc-naphthylamines and 1-DNQs
(color online)
a) Unless otherwise specified, reactions were performed with 5 (0.20 mmol), 2 (0.30 mmol) and Pd(OAc)2 (5 mol%) in DCM (2.0 mL) at room
temperature for 36 h. b) Isolated yield.
lenging and complicated due to the disparate nucleophilicity
as well as multiple reactive sites. Pleasingly, this set of
conditions also adequate for the reaction of 2-naphthyla-
mines and 1-DNQs and the optimal results with 77% isolated
yield for 6a were readily attained by subtle modulation of the
loading of 2m (1.5 equiv.) and Pd(OAc)2 (5 mol%). It is
worth noting that in Liu’s work [11], the C–H arylation of N-
phenylacetamide with diazo quinones in the presence of Ir
(III)-catalyst occurred at C3-position of N-acetyl-naphthy-
lamine, and thus hampered the application in NOBINs
synthesis.
The re-optimized conditions were then applied to various
1-DNQs and 2-naphthylamines to extend the generality of
the substrate. As shown in Table 3, all these reactions dis-
played high site-selectivity and furnished the desired NOBIN
derivatives bearing different functional groups in moderate
to good efficiency (6a–6q). Meanwhile, the experimental
results revealed that 9-diazo-10-phenanthrone presented
better reactivity than 1-DNQs with a naphthyl ring (6a–6h
vs. 6i–6o). Expectedly, the bromo substituent was success-
fully retained under our developed conditions.
HCl, to give NOBIN 7a in a 95% yield. The one-pot two-step
synthesis of 7a was performed and inconspicuous change in
yield was observed (Scheme 2(b)). The catalytic asymmetric
variant of this transformation was also attempted to approach
optically active BINOLs. After extensive investigations of
the palladium/chiral ligand system, we found that chiral
phosphoric acids (CPA) [12] could effectively induce the
enantiocontrol in the presence of [(η3-C3H5)PdCl]2. Al-
though only moderate yields and enantiopurities were ob-
tained for both 3q and 3k at the present stage, the good
compatibility between CPA and palladium catalyst created
the possibility for highly enantioselective arylation of 2-
naphthols of 1-DNQs (Scheme 2(c)).
On the basis of previous reports [7f, 7g,10c,13] concerning
the reaction with diazo compounds and our understandings
on the construction of biaryl atropisomers, two plausible
pathways were rationalized as follows (using 1a as a model;
Scheme 3): pathway a is the metal-carbene process. The
catalytic cycle commences with the generation of metal-
carbenoid A from 1-DNQ 2a and metal catalyst along with
the releasing of N2. The multiple interactions between A and
2-naphthol 1a enable the C–C bond formation to afford in-
termediate C via B. Following re-aromatization of inter-
mediate C produces the desired product BINOL 3a and
meanwhile regenerates the catalyst. In pathway b, palladium
species serves as a Lewis acid and the catalytic cycle is
initiated from the coordination between metal center and the
The gram-scale reactions were performed to demonstrate
the utility of this strategy. Under the standard conditions, 3a,
3ae and 6a all delivered with high efficiency, implying that
this protocol should be well suited for large-scale chemical
production (Scheme 2(a)). Furthermore, the Boc protecting
group of 6a could be readily removed by the treatment with

6
Zhang et al. Sci China Chem
Scheme 2 (a) Gram-scale preparation of 3a, 3ae as well as 6a and their transformation; (b) one-pot two-step synthesis of 7a; (c) initial asymmetric attempts
of BINOLs (color online).
Scheme 3 Proposed reaction pathways (color online).
oxygen and/or nitrogen of 1-DNQ 2a (intermediate A’).
Subsequent ligand change with 2-naphthol 1a generates B’
and then the intramolecular nucleophilic addition occurs to
give the same intermediate C.

7
Zhang et al. Sci China Chem
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4 Conclusions
In summary, we have established an efficient approach for
the synthesis of BINOLs and NOBIN derivatives employing
1-DNQs as arylation reagents under mild conditions. Palla-
dium catalyst was verified to be most effective to inhibit the
undesired X–H insertion reactions for both 2-naphthols and
N-Boc-2-naphthamines. This approach demonstrated fairly
good functional group compatibility to give the structurally
diversified BINOLs and BONIN derivatives with up to 94%
yield. Particularly, the amendable substituents bearing bromo
substituent for this set of conditions offered efficient plat-
form molecules for downstream coupling reactions under
transition metal catalysis. The enantioselective variant for
the BINOLs synthesis was also conducted and moderate
atroposelectivities could be obtained at the present stage.
Further applications on the construction of other biaryl
skeletons and the exploitation of highly enantioselective
variants are ongoing in our group.
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Acknowledgements This work was supported by the National Natural
Science Foundation of China (21825105), the Guangdong Provincial Key
Laboratory of Catalysis (2020B121201002), the Guangdong Innovative
Program (2019BT02Y335), the Shenzhen Nobel Prize Scientists Laboratory
Project (C17213101), and the SUSTech Special Fund for the Construction of
High-Level Universities (G02216402). The authors appreciate the assis-
tance of SUSTech Core Research Facilities.
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Conflict of interest The authors declare no conflict of interest.
Supporting information The supporting information is available online at
http://chem.scichina.com and http://link.springer.com/journal/11426. The
supporting materials are published as submitted, without typesetting or
editing. The responsibility for scientific accuracy and content remains en-
tirely with the authors.
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