An efficient suzuki-miyaura coupling of aryl sulfamates and boronic acids catalyzed by NiCl2(dppp)

Article abstract of DOI:10.1002/ejoc.201200444

The Suzuki-Miyaura cross-coupling of aryl sulfamates and boronic acids was investigated by using [1,3-bis(diphenylphosphanyl)propane]nickel(II) chloride {NiCl₂(dppp)} as the catalyst. The results showed that NiCl ₂(dppp) is a highly active and general catalyst that allows effective Suzuki-Miyaura cross-coupling of aryl sulfamates with a slight excess amount of the boronic acid (1.2 equiv.) in the presence of a low catalyst loading (generally 1.0-1.5 mol-%). The method also displays broad generality not only to various aryl sulfamates, but also to an array of boronic acids. Furthermore, various functional groups are tolerated. These apparent advantages make NiCl₂(dppp) a practical and reliable catalyst system for the Suzuki-Miyaura coupling of aryl sulfamates.

Full text of DOI:10.1002/ejoc.201200444

SHORT COMMUNICATION
DOI: 10.1002/ejoc.201200444
An Efficient Suzuki–Miyaura Coupling of Aryl Sulfamates and Boronic Acids
Catalyzed by NiCl (dppp)
2
[a]
[a,b]
Guo-Jun Chen and Fu-She Han*
Keywords: Nickel / Cross-coupling / Sulfur / Boronic acids / Biaryls
The Suzuki–Miyaura cross-coupling of aryl sulfamates and
boronic acids was investigated by using [1,3-bis(diphenyl-
low catalyst loading (generally 1.0–1.5 mol-%). The method
also displays broad generality not only to various aryl sulfam-
ates, but also to an array of boronic acids. Furthermore, vari-
ous functional groups are tolerated. These apparent advan-
phosphanyl)propane]nickel(II) chloride {NiCl
2
(dppp)} as the
catalyst. The results showed that NiCl (dppp) is a highly
2
active and general catalyst that allows effective Suzuki–Mi-
yaura cross-coupling of aryl sulfamates with a slight excess
amount of the boronic acid (1.2 equiv.) in the presence of a
2
tages make NiCl (dppp) a practical and reliable catalyst sys-
tem for the Suzuki–Miyaura coupling of aryl sulfamates.
Introduction
tocols required a high catalyst loading and a large excess
amount of the boronic acids. In addition, some of the reac-
Recently, the transition-metal-catalyzed cross-coupling
of phenol/enol derivatives has received intense interest due
to the wide availability and cheapness of phenolic com-
pounds and the great importance of biaryl compounds in a
broad range of areas.[ Among various coupling reactions,
the Suzuki–Miyaura cross-coupling is especially attractive
because it involves the advantageous use of boronic acids
as nucleophiles, which are stable to air and moisture and
widely available, they show low toxicity and good func-
tional group tolerance, and boron-containing byproducts
can be easily purified.[ One of the key efforts involved in
this transformation is the development of an effective acti-
vating reagent that could activate the inert phenolic C–O
bond for practical and reliable coupling by employing a
stable, readily available, and cheap Ni-based catalyst. So far,
numerous protocols have been developed including the use
tions necessitated the use of additional phosphane ligands.
[7b–7d]
For instance, aryl sulfamate,
which has been shown to
be the most competent electrophile discovered so far, re-
quired essentially 5–10 mol-% of NiCl (PCy ) associated
2
3 2
1]
with the use of 2.5–4.0 equiv. of boronic acids and 4.0–
.2 equiv. of K PO base. More to the point, even under
7
3
4
these severe conditions, the coupling efficiency for many of
the phenol derivatives was only moderate except for aryl
sulfamates. Thus, the development of a highly active cata-
lyst system that allows the effective coupling of phenolic
derivatives under more simplified conditions, for example,
a significantly lowered catalyst loading and a low molar
ratio of phenol derivative and boronic acid (ideally 1:1) re-
mains an urgent demand for practical applications.
2]
In our previous studies, we demonstrated that NiCl2-
(dppp) was an efficient catalyst for the Suzuki–Miyaura
[
3]
[4]
[4l,5]
[4l,6]
of an aryl triflate, sulfonate, ether,
ester,
carb-
cross-coupling of various phenol derivatives such as aryl
[
4l,7]
[4l,7b]
[4k,4l,7b–7d]
[8]
amate,
carbonate,
sulfamate,
phenolate,
[
10]
[11]
[4j]
phosphoramide, phosphonium salt, tosylate, mesyl-
[
9]
[10]
phosphonium salt,[11] and
sulfate,
phosphate,
phosphoramide,
[
4j]
[14]
ate, and halides. Of particular note is that this catalyst
is capable of catalyzing the cross-coupling of conventionally
less reactive aryl tosylates, mesylates, and chlorides with a
catalyst loading of lower than 1 mol-% without the need of
an external supporting ligand. In addition to its high ac-
[
12]
and even more elegantly by the mutual acti-
vation of C–O and C–B bonds as developed very recently
[
13]
by Shi.
In the above-mentioned coupling reactions, NiCl2-
PCy ) was the most frequently used catalyst owing to its
(
3
2
tivity, NiCl (dppp) is also more stable and cheaper than
2
ready availability and stability. However, most of these pro-
[
15]
NiCl (PCy ) .
To best use this catalyst system, we initi-
2
3 2
ated an investigation into the Suzuki–Miyaura coupling of
aryl carbamates and sulfamates, as these substrates have the
added advantages that they can direct the installation of
functional groups onto the aromatic ring and they have
[
a] Changchun Institute of Applied Chemistry,
Chinese Academy of Sciences,
5
625 Renmin Street, Changchun, Jilin 130022, P. R. China
Fax: +86-431-8526-2926
E-mail: fshan@ciac.jl.cn
[
7]
[b] State Key Laboratory of Fine Chemicals,
Dalian University of Technology,
good leaving ability. Herein, we present that NiCl (dppp)
2
is also a highly active catalyst for practical and reliable
cross-coupling of aryl sulfamates and boronic acids. Our
results showed that, under the optimized conditions, the re-
Dalian 116024, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201200444.
Eur. J. Org. Chem. 2012, 3575–3579
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3575

G.-J. Chen, F.-S. Han
SHORT COMMUNICATION
action proceeds smoothly with only a slight excess amount Table 1. Suzuki–Miyaura cross-coupling of various sulfamates and
boronic acids.[
a]
of the boronic acid (1.2 equiv.) in the presence of a signifi-
cantly lowered catalyst loading (1–1.5 mol-%). These results
provide an important advance for the Suzuki–Miyaura
cross-coupling of aryl sulfamates.
Results and Discussion
At the outset, the catalytic activity of NiCl (dppp) for
2
the cross-coupling of aryl sulfamates and carbamates was
evaluated by employing the coupling of 1-naphthyl sulf-
amate (1a) or 1-naphthyl carbamate (1aЈ) with 4-meth-
oxyphenyl boronic acid (2a) as the model reactions
[
16]
(Scheme 1).
After a brief optimization of the reaction
conditions on the basis of our previous experi-
[
4j,10,11,14]
ences,
we quickly found that whereas the reaction
of carbamate 1aЈ and 2a was inefficient, sulfamate 1a could
couple smoothly with only a slight excess amount of 2a
(
1.2 equiv.) in the presence of 1 mol-% of NiCl (dppp) as
2
catalyst and 4.0 equiv. of K PO as base in dioxane at
3
4
100 °C. Under these conditions, desired product 3a was ob-
tained in 84% yield.
Scheme 1. Comparison of the reactivity of 1-naphthyl sulfamate
and 1-naphthyl carbamate.
We then examined the substrate scope and limitation of
these conditions. The results show that the reaction condi-
tions exhibit good structural compatibility both to aryl sulf-
amates and boronic acids. As shown in Table 1, unsubsti-
tuted 1-naphthyl sulfamate (1a) and 2-naphthyl sulfamate
(
1b) coupled smoothly with a range of boronic acids, whose
structures are decorated by electron-donating OMe
Table 1, Entry 1; 2a), neutral H (Table 1, Entry 2; 2b), and
(
Me groups (Table 1, Entries 3 and 4; 2c and 2d), as well as
electron-withdrawing CO Me groups (Table 1, Entry 5; 2e)
2
to afford desired products 3a–f in high yields. Notably, a
good yield (76%) for 3d implies that the transformation is
also tolerant of ortho-substituted boronic acid. In addition,
efficient coupling was also observed for other naphthyl sulf-
amates modified by either an electron-deficient group such
as CO Me (Table 1, Entries 7 and 8; 1c) and CN groups
2
(Table 1, Entries 9–11; 1d) or an electron-rich group such
as OMe (Table 1, Entries 12 and 13; 1e), although a catalyst
loading of 2 mol-% was required for electron-rich substrate
[
2
a] Reaction conditions: Aryl sulfamate 1 (0.5 mmol), boronic acid
(0.6 mmol), K PO (2.0 mmol, 4.0 equiv.), dioxane (3 mL), 100–
110 °C, 12–24 h; unless otherwise noted, 1.0 and 1.5 mol-% of
NiCl (dppp) loading, respectively, for the naphthyl-based sulfam-
3
4
1e.
Next, we extended the technology to non-fused aromatic
sulfamates. This is far more challenging because of the less
delocalized nature of the aromatic ring (i.e., less electron-
2
ates and non-fused aromatic sulfamates. [b] Isolated yield. [c] Yield
was determined by H NMR spectroscopy due to the contami-
nation of a small amount of hard-to-separate byproduct derived
1
deficient system). The results show consistently with the ge- from homocoupling of the boronic acid. [d] A catalyst loading of
[
5–11]
neral observations
that non-fused aryl sulfamates were 2 mol-% was used. [e] A catalyst loading of 3 mol-% was used.
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An Efficient Suzuki–Miyaura Coupling of Aryl Sulfamates
somewhat less reactive than the fused aromatic analogues. coupling of 2-halopyridines.[17] Nevertheless, herein we
However, efficient coupling could be achieved under condi- showed that 2-pyridyl sulfamates would be viable substrates
tions that were otherwise identical to those used to couple to couple with boronic acids in the presence of a low load-
naphthyl sulfamates except that the catalyst loading was in- ing of NiCl (dppp) as the catalyst.
2
creased from 1.0 to 1.5 mol-%. Under these slightly altered
Having exemplified the high activity and the broad sub-
conditions, aryl sulfamates activated by electron-with- strate scope of NiCl (dppp) for the Suzuki–Miyaura cross-
2
drawing groups such as ester (Table 1, Entries 14 and 15; 1f) coupling of aryl sulfamates, we became interested in ob-
and cyano groups (Table 1, Entries 16–19; 1g) were viable taining further insight into the reactivity difference between
coupling partners. They were coupled smoothly with an ar- aryl sulfamates and tosylates or mesylates. The two classes
ray of boronic acids substituted by electron-donating OMe, of substrates have shown to be competent electrophiles[18]
simple H, and electron-withdrawing CO Me groups, as well in the presence of the NiCl (dppp) catalyst and are readily
2
2
as sterically hindered boronic acid (Table 1, Entry 18; 3r). available and markedly stable for handling, but each class
Moreover, ortho-cyano substituted substrate 1h (Table 1, of substrate has their distinctive advantages. Typically, as
Entry 20) could also be coupled smoothly to give 3t in high an important advantage, the sulfamyl group may serve as a
yield in the presence of 1.2 equiv. of boronic acid and latent directing group for the installation of other func-
3
mol-% of the catalyst. The effective coupling of sterically tional groups onto the aromatic ring at the ortho/para posi-
[
7]
hindered 1h is important, because it can be potentially used tion prior to cross-coupling. Aryl tosylates or mesylates
for synthesizing the key intermediate of antihypertensive are much cheaper than aryl sulfamates due to the consider-
[
7d,14]
sartan drugs.
i) and non-activated (Table 1, Entry 22; 1j) substrates were parison to the cost of N,N-dimethylsulfamoyl chloride.[
somewhat challenging, affording the coupled product in sig- Furthermore, the preparation of aryl sulfonates is more
nificantly lower yields. convenient than that of aryl sulfamates, because triethyl-
However, deactivated (Table 1, Entry 21; ably lower cost of tosyl chloride or mesyl chloride in com-
19]
1
Finally, the coupling efficiency of N-heteroaromatic sul- amine is used as the base instead of sodium hydride for the
famates was investigated as represented by N-3 (Table 1, preparation of aryl sulfonates. Therefore, an investigation
Entries 23–25; 1k) and N-2 heteroarenes (Table 1, En- into the reactivity difference between aryl sulfamates and
tries 26 and 27; 1l). Both 3- and 2-pyridyl derivatives 1k sulfonates would provide important information for choos-
and 1l could be coupled uneventfully with electron-rich (i.e., ing suitable activating reagents when a particular synthetic
2a), neutral (i.e., 2b), and electron-deficient boronic acids application is under consideration.
(
i.e., 2e). These results suggest that the method is also appli-
Accordingly, the reactivity of 1-naphthyl sulfamate (1a)
and 1-naphthyl tosylate (4) was compared through the cou-
cable to heteroaryl sulfamates.
Here, a little more attention should be given to 2-quino- pling with 4-methoxyphenyl boronic acid (2a) under iden-
lyl sulfamate (1l): a somewhat higher catalyst loading of tical reaction conditions [Equations (2) and Equation (3)].
3
mol-% was required for this substrate compared with The results showed that in the presence of only 1.0 equiv.
other substrates. Of the Ni-catalyzed Suzuki–Miyaura of boronic acid and 1 mol-% of NiCl (dppp) as catalyst, the
2
cross-coupling reactions of N-heterophenolic derivatives, two different substrates display equally high reactivity with
the 3- and 4-pyridyl derivatives have been extensively ca. 55% yield of product 3a observed for both reactions
[4j,7a,10,11a]
[20]
studied, and the reactions proved to be successful.
after heating the reaction mixture for 0.5 h.
Complete
However, only very few examples of 2-OH pyridine ana- conversion as well as high yields (85 and 80%, respectively)
logues have been reported, and these couplings were unsuc-
cessful. This is in sharp contrast to the great importance of
2-arylated pyridyl compounds in a wide spectrum of areas
such as catalysis, coordination, and functional materials. In
[
11b]
[7a]
fact, we
and other groups have experienced problems
in Ni-catalyzed Suzuki–Miyaura couplings of 2-OH pyr-
idine derivatives. Most possibly, this is due to the unique
structural features of the 2-pyridyl scaffold, which is ready
to form an N-containing six-membered chelate with the Ni
[
11b]
catalyst
[e.g., B in Equation (1)], and thereby, sup-
pressing the activity of the catalyst. Indeed, similar coordi-
nation effects have also been observed in Pd-catalyzed Heck
Eur. J. Org. Chem. 2012, 3575–3579
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3577

G.-J. Chen, F.-S. Han
SHORT COMMUNICATION
was observed when the reaction time was elongation to 1 h.
These results indicate that aryl sulfamates and tosylates dis-
play similar high reactivity in the presence of the NiCl2-
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(dppp) catalyst.
1
5
759; d) J. D. Sellars, P. G. Steel, Chem. Soc. Rev. 2011, 40,
170–5180.
Conclusions
[
[
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NiCl (dppp) is a highly active and generally applicable cata-
2
lyst for the Suzuki–Miyaura cross-coupling of aryl sulfam-
ates and boronic acids, although deactivated and non-acti-
vated phenyl sulfamates are somewhat less reactive. This
catalyst offers several advantages over the frequently used
NiCl (PCy ) catalyst. Namely, effective coupling proceeds
[
4] For some representative examples, see: a) V. Percec, J.-Y. Bae,
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2
3 2
smoothly with only a slight excess amount of the boronic
acid (1.2 equiv.) as well as a significantly lowered catalyst
loading of 1–1.5 mol-% for most of the substrates. In con-
trast, 2.5–4.0 equiv. of the boronic acid in the presence of a
catalyst loading of 5–10 mol-% was essentially required
when NiCl (PCy ) was employed as catalyst. In addition
3447–3452; f) D. A. Wilson, C. J. Wilson, B. M. Rosen, V. Per-
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2
3 2
to the high catalytic efficiency, the NiCl (dppp) complex is
2
more stable towards air and moisture than NiCl (PCy ) ,
2
3 2
which can be attributed to a combination of the bidentate
and aromatic nature of the dppp ligand. Finally, dppp is
[15]
much cheaper than the PCy ligand. Owing to the afore-
3
mentioned advantages, NiCl (dppp) presented herein would
2
[5] M. Tobisu, T. Shimasaki, N. Chatani, Angew. Chem. 2008, 120,
be a more appealing catalyst for the transition-metal-cata-
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2
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Experimental Section
General Procedure for the Suzuki–Miyaura Cross-Coupling Reaction
of Aryl Sulfamates with Arylboronic Acids: To a 25-mL Schlenk
tube equipped with a magnetic bar was added NiCl
17748–17749; c) K. W. Quasdorf, A. Antoft-Finch, P. Liu,
A. L. Silberstein, A. Komaromi, T. Blackburn, S. D. Ramgren,
2
(dppp)
K. N. Houk, V. Snieckus, N. K. Garg, J. Am. Chem. Soc. 2011,
(amount indicated in Table 1), the aryl sulfamate (0.5 mmol,
133, 6352–6363; d) M. Baghbanzadeh, C. Pilger, C. O. Kappe,
1
.0 equiv.), the arylboronic acid (0.6 mmol, 1.2 equiv.), and anhy-
PO (2.0 mmol, 4.0 equiv.). The tube was then evacuated
3ϫ10 min) under vacuum and backfilled with N . Dried dioxane
3.0 mL) was injected by syringe, and the reaction mixture was
J. Org. Chem. 2011, 76, 1507–1510; e) L. Xu, B.-J. Li, Z.-H.
Wu, X.-Y. Lu, B.-T. Guang, B.-Q. Wang, K.-Q. Zhao, Z.-J. Shi,
Org. Lett. 2010, 12, 884–887.
drous K
(
(
3
4
2
[8] D.-G. Yu, B.-J. Li, S.-F. Zheng, B.-T. Guan, B.-Q. Wang, Z.-J.
Shi, Angew. Chem. 2010, 122, 4670–4674; Angew. Chem. Int.
Ed. 2010, 49, 4566–4570.
stirred at 100–110 °C until the aryl sulfamate had disappeared as
monitored by TLC. The reaction mixture was then poured into
[
[
[
9] B.-T. Guan, X.-Y. Lu, Y. Zheng, D.-G. Yu, T. Wu, K.-L. Li,
water (20 mL) and extracted with CH
bined organic layer was dried with anhydrous Na
concentrated to dryness. The crude material was purified by flash
chromatography (silica gel, hexane/CH Cl or hexane/ethyl acetate)
to give the desired cross-coupled products.
2
Cl
2
(3ϫ10 mL). The com-
B.-J. Li, Z.-J. Shi, Org. Lett. 2010, 12, 396–399.
2
SO , filtered, and
4
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2
2
11] a) G.-J. Chen, J. Huang, L.-X. Gao, F.-S. Han, Chem. Eur. J.
2
011, 17, 4038–4042; b) S.-M. Li, J. Huang, G.-J. Chen, F.-S.
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Supporting Information (see footnote on the first page of this arti-
[
[
[
[
12] H. Chen, Z. Huang, X. Hu, G. Tang, P. Xu, Y. Zhao, C.-H.
cle): General information and reaction procedure, product charac-
1
13
Cheng, J. Org. Chem. 2011, 76, 2338–2344.
terization, copies of the H NMR and C NMR spectra.
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F.-S. Han, Adv. Synth. Catal. 2011, 353, 1543–1550.
15] The approximate costs of the ligands are: bis(diphenylphos-
phanyl)propane (dppp, 97%) = RMB 2,342/25 g; tricyclohexyl-
phosphane (PCy3) = RMB 3,101/25 g (Sigma–Aldrich cata-
Acknowledgments
Financial support from the Hundred Talent Program and Acad-
emy-Locality Cooperation Program of the Chinese Academy of
Sciences (CAS) and the State Key Laboratory of Fine Chemicals
logue, 2009–2010). Moreover, 2 equiv. of PCy is needed for the
3
(KF1008) is acknowledged.
2 3 2
preparation of NiCl (PCy ) .
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Eur. J. Org. Chem. 2012, 3575–3579

An Efficient Suzuki–Miyaura Coupling of Aryl Sulfamates
[
16] NiCl (dppp) used in our experiments was prepared following
[19] The approximate reagent costs are: tosyl chloride (Ն99%) =
RMB 806/500 g; methanesulfonyl chloride (Ն99.7%) = RMB
1109/500 mL; N,N-dimethylsulfamoyl chloride (99%) = RMB
2
the known method; see: G. R. Van Hecke, W. D. Horrocks Jr.,
Inorg. Chem. 1966, 5, 1968–1974.
5
684/500 g (Sigma–Aldrich catalogue, 2009–2010).
[17] K. Nakatsu, K. Kinoshita, H. Kanda, K. Isobe, Y. Nakamura,
S. Kawaguchi, Chem. Lett. 1980, 913–914.
[
20] The yields was determined by using HPLC with compound 3e
(see Table 1, Entry 5) as external standard.
Received: April 6, 2012
[
4j]
[18] See ref. for the NiCl
2
(dppp)-catalyzed Suzuki–Miyaura cou-
pling of aryl tosylates and mesylates.
Published Online: May 29, 2012
Eur. J. Org. Chem. 2012, 3575–3579
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3579