Cobalt-Catalyzed Electrophilic Cyanation of Arylzinc Halides with N-Cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS)

Article abstract of DOI:10.1002/adsc.201500245

The cobalt-catalyzed cross-coupling of organozinc bromides with N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS) is described. The same cobalt catalyst, cobalt(II) bromide, was used for both the synthesis of the organozinc species and the cross-coupling reaction. However in this case, a catalytic amount of zinc dust is necessary in the second step to release the low-valent cobalt. Under these mild conditions, moderate to excellent yields of different benzonitriles were obtained.

Full text of DOI:10.1002/adsc.201500245

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DOI: 10.1002/adsc.201500245
Very Important Publication
Cobalt-Catalyzed Electrophilic Cyanation of Arylzinc Halides
with N-Cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS)
Yingxiao Cai,a Xin Qian,a Alice RØrat,a Audrey Auffrant,a and Corinne Gosminia,*
a
Laboratoire de Chimie MolØculaire, Ecole Polytechnique, CNRS, UMR 9168, Route de Saclay, 91128 Palaiseau Cedex,
France
Fax: (+33)-1-6933-4440; phone (+33)-1-6933-4400; e-mail: corinne.gosmini@polytechnique.edu
Received: March 11, 2015; Revised: June 11, 2015; Published online: August 13, 2015
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201500245.
Abstract: The cobalt-catalyzed cross-coupling of or-
ganozinc bromides with N-cyano-N-phenyl-p-meth-
ylbenzenesulfonamide (NCTS) is described. The
same cobalt catalyst, cobalt(II) bromide, was used
for both the synthesis of the organozinc species and
the cross-coupling reaction. However in this case,
a catalytic amount of zinc dust is necessary in the
second step to release the low-valent cobalt. Under
these mild conditions, moderate to excellent yields
of different benzonitriles were obtained.
nide reagents, and the generation of HCN. Then, al-
ternative routes for the cyanation reactions employing
“non-CN-unit” were described but they also generally
require a stoichiometric amount of metal salt and
harsh conditions.[12]
Electrophilic cyanations have been less studied
compared to nucleophilic ones. However, they repre-
sent useful complementary alternatives, which some-
times overcome the above-mentioned drawbacks. Dif-
ferent aryl-organometallic reagents react with a varie-
ty of cyano sources. Aryllithium reagents react with
cyanatobenzene[13] or ClCN at low temperature.[14] In
the early years, the nucleophilic displacement of p-tol-
uenesulfonyl cyanide[15] or 2-pyridyl cyanate[16] with
phenylmagnesium bromide was also investigated. The
scope of the Grignard reagents has only been ex-
plored in 2010 by Beller and co-workers who reported
Keywords: benzonitriles; cobalt; cross-coupling;
electrophilic cyanation; organozinc compounds
Benzonitriles play an important role in natural prod- the electrophilic cyanation of aryl/heteroaryl
ucts, pharmacy, dyes and electronic materials.[1] Mean- Grignard reagents with N-cyanobenzimidazole.[17] In
while the nitrile group allows a multitude of transfor- addition, the first Pd-catalyzed, Cu-mediated [CuTC:
mations to other important functional groups, such as copper(I)-thiophene-2-carboxylate] efficient cyana-
amines, amidines, tetrazoles, aldehydes, amides.[2] In tion of arylboronic acids with benzyl thiocyanates was
the early years, the Sandmeyer[3] and Rosenmund– reported by Liebeskind and co-workers.[18] However,
von Braun[4] reactions were the two most employed the main drawbacks of these methods are the prepa-
methods for the introduction of a cyano group onto ration of the cyano reagent from cyanogen bromide,
arenes using CuCN and relatively harsh conditions. which is quite toxic and dangerous. To avoid this,
However, both these drawbacks and the restricted later, Bellerꢀs group developed an elegant, novel and
functional tolerance, encourage researchers to find convenient synthesis of benzonitriles through aryl/het-
new methodologies to achieve the formation of most eroaryl Grignard reagents,[19] prepared via Knochelꢀs
functionalized benzonitriles.
procedure,[20] using a benign cyanating reagent, N-
In the past few decades, transition metals (Pd, Cu, cyano-N-phenyl-p-methylbenzenesulfonamide
or Ni) catalyzed nucleophilic cyanation reactions of (NCTS). NCTS is a bench-stable, easy to handle and
aryl substrates have emerged as powerful alternatives. environmentally benign electrophilic cyanating agent.
Various cyanide sources, such as CuCN,[5] KCN,[6] Compared to the previous established electrophilic
NaCN,[7] Zn(CN)2,[8] TMSCN,[9] acetone cyanohy- cyanating sources, its synthesis does not require the
drin[10] or K4[Fe(CN)6][11] have been reacted with func- highly toxic cyanogen halides, or similar cyanating
tionalized aryl halides to provide the corresponding precursors.[21] Substituted arenes were cyanated in
aryl nitriles. However, some limitations remain: the high yields and these methods tolerate both electroni-
high affinity of the cyanide ion towards the catalyst cally rich/poor groups at any place of the arene.[19]
implies high catalyst loading, the toxicity of the cya- This methodology is cost-effective and environmental-
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ly friendly. The same year, the same group extended
this methodology to arylboronic acids using this time
Rh catalysis.[22] More recently, new Rh,[23] Ru,[24]
Cu,[25] or Co[26] catalyzed directed C H cyanation re-
À
actions were developed using this user-friendly cyana-
tion reagent. Nevertheless, the functionalization of
À
unactivated C H bonds required a directing group
and high temperature. In the same manner, a direct
oxidative cyanation of arenes under Fe(II) catalysis
using an excess of aryl(cyano)-iodonium triflates as
the cyanating agent has been successfully applied to
a range of electron-donating substituents on aromatic
substrates.[27] Although some elegant results were re-
Scheme 1. Cobalt-catalyzed electrophilic cyanation of aryl-
zinc species.
À
ported by C H activation, organometallic reagents
remain useful to functionalize aryl halides without
a directing group. Nevertheless, organozinc com-
pounds known for their broad functional tolerance
were rarely employed in cyanation. Noteworthy, some
twenty years ago, Knochelꢀs group developed the only
efficient transition metal-free procedure for the cyan-
ation of a wide range of organozinc compounds at
low temperature using toxic p-toluenesulfonyl cya-
nide.[28]
Table 1. Optimization of reaction conditions.
All these umpolung procedures have made impor-
tant contributions to the synthesis of aryl nitriles.
Many efficient methodologies have been developed.
However, all these methods suffer from some draw-
backs in that they require either the use of stoichio-
metric co-catalyst or additive, or expensive catalyst,
or dangerous CN source. Moreover, high or very low
temperatures are often necessary to ensure a good
yield. Thus, despite impressive recent progress, the
development of a mild, inexpensive, and simple pro-
cedure remains highly desirable. Arylzinc reagents,
whose synthesis is well understood by our group, are
good candidates as nucleophilic partners taking into
account their special reactivity. Thus, this paper pres-
ents the cyanation of arylzinc reagents using the
benign NCTS as the electrophilic CN source in order
to form a variety of functionalized aryl nitriles
(Scheme 1).
Entry Conditions
Yield
1
2
3
4
08C to r.t., 3 h or 12 h
45%[a]
30%[b]
38%[b]
<5%[b]
filtration of ArZnBr, 08C to r.t., 12 h
filtration of ArZnBr, 08C to 508C, 12 h
filtration of ArZnBr, add THF, 08C to
508C, 12 h
5
6
7
8
9
filtration of ArZnBr, add 10 mol% of Zn,
08C to r.t. 16 h
filtration of ArZnBr, add 10mol% of Zn,
08C to 508C 3
filtration of ArZnBr, add 5 mol% of Zn,
08C to 508C 3 h
67%[b]
84%[a]
43%[b]
50%[b]
77%[b]
filtration of ArZnBr, add 20 mol% of Zn,
08C to 508C 3 h
filtration of ArZnBr,[c] 08C to 508C, 3 h
[a]
[b]
[c]
Isolated yield.
GC yield (decane as internal standard).
ArZnBr formed with [CoBr2(bpy)].
Using the method we developed to synthesize aryl-
zinc bromides with a CoBr2/Zn catalytic system, we
first examined the reaction of p-methoxyphenylzinc
bromide, formed by cobalt catalysis, with N-cyano-N- with NCTS when ArZnX is formed with the simple
phenyl-p-toluenesulfonamide (Table 1). Adding the CoBr2. Therefore, the yield increases on adding
NCTS directly to the crude solution of arylzinc bro- 10 mol% of Zn in the medium (Table 1, entry 5) and
mide affords the desired 4-methoxybenzonitrile in is better at 508C (Table 1, entry 6). This catalytic
modest yield (Table 1, entry 1). Previously, we have amount of zinc is optimum (Table 1, entries 6, 7, 8).
shown that zinc can be easily removed,[29] but in this
In order to understand the role of the catalytic
reaction, filtration decreases the yield (Table 1, amount of zinc dust in the second step, we have re-
entry 2). Carrying out the reaction at 508C instead of placed it by 10 mol% of other metals such as Mg, Fe,
room temperature, increases the yield (Table 1, Mn and Cu and obtained lower GC yields of, respec-
entry 3), whereas introduction of THF in the medium, tively, 31, 0, 53 and 14%. Replacement of Zn by
inhibits the reaction (Table 1, entry 4). Moreover, ad- a Lewis acid such as ZnCl2 to facilitate the desired cy-
dition of a catalytic amount of zinc dust in the second anation gave no cyanated product. Therefore, we
step is essential for the success of the cross-coupling thought that Zn dust should help the release of the
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Cobalt-Catalyzed Electrophilic Cyanation of Arylzinc Halides
group are less efficient. However, these compounds
are relatively unstable, so that the yield cannot be in-
creased. Therefore, we focused our study on the
NCTS previously used by Beller and we set out to ex-
plore the scope of the methodology.
A variety of arylzinc bromides bearing electron-do-
nating or electron-withdrawing groups were coupled
with NCTS under the optimized conditions defined
above to afford functionalized benzonitriles in moder-
ate to excellent yields (Table 2). It should be noted
that some of them are quite difficult to obtain by the
electrophilic cyanation of Grignard reagents, since
ArMgX are too strong nucleophiles to tolerate some
of those functional groups.
A methoxy group on the para-position of the arene
is the more favorable substituent, the yields are lower
when it is located at the meta- or ortho-position.
(Table 2, entries 1 to 3). Small groups like methyl or
fluoro on the ortho-position still provided excellent
yields (Table 2, entries 4 and 5). Aryl halides without
any substitutent (Table 2, entry 6), or with a variety of
Scheme 2. Analogous cyanide sources.
Table 2. Cobalt-catalyzed cross-coupling of various function-
alized arylzinc bromides with NCTS.
cobalt catalyst from the cyano group, since the elec-
trophilic amination with RR’N-Cl carried out under
the same conditions (acetonitrile) works well without
zinc.[29a] This was further confirmed by preparing the
arylzinc species with [CoBr2(bpy)] which is able to
“protect” the cobalt from the cyano group (Table 1,
entry 9). In this case, a good yield is obtained without
supplementary addition of zinc in the second step.
However, we have preferred to use commercially
available CoBr2 as catalyst and add zinc dust in the
second step for economic reasons. This study shows
also that cobalt is necessary for the cross-coupling of
arylzinc derivatives with NCTS whereas it is not re-
quired for more reactive Grignard reagents.
Entry FG in FG-C6H4-CN[a]
Reaction time Yield[b]
1
2
3
4
p-MeO (1a)
m-MeO (1b)
o-MeO (1c)
o-Me (1d)
2.5 h
2.5 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
6 h
84%
57%
58%
98%
82%
76%
76%
40%
63%
74%
47%[c]
68%
68%
72%
79%
40%[d]
56%
79%
34%[e]
45%[e]
50%[e]
5
6
2-F,5-Me (1e)
H (1f)
7
8
9
p-MeS (1g)
p-MeOCO (1h)
p-Cl (1i)
Different substituted arylsulfonylcyanamides were
tested (Scheme 2), which were synthesized by reacting
substituted arylsulfonyl chlorides with substituted ary-
lureas in pyridine at room temperature, to deliver B,
C and D. No improvement was observed using these
10
11
12
13
14
15
16
17
18
19
20
21
p-F (1j)
p-MeSO2 (1k)
p-CF3 (1l)
p-Me2N (1m)
p-EtO2C (1n)
À
alternative cyano sources. Other N CN reagents, N-
1,2-(methylenedioxy) (1o) 6 h
carbomethoxy-N-arylcyanamides (E, F, G, H)
(Scheme 2), were also synthesized in three steps from
the corresponding commercial benzonitriles to see the
influence of the groups on nitrogen and to compare
them with arylsulfonylcyanamides. Compounds E, F,
G and H were obtained in 26 to 58% overall yields.
These cyano sources are much more reactive than ar-
ylsulfonylcyanamides and the reaction time can be re-
duced to 15 min. Good yields of cyanated products
are obtained from E and H bearing an electron-do-
nating substituent, whereas compounds F and G with
an electron-withdrawing groups on the N-phenyl
3,5-diCF3 (1p)
3,5-diMe (1q)
1-naphthyl (1r)
p-MeCO (1s)
p-PhCOPh (1t)
p-NC (1u)
6 h
6 h
6 h
6 h
6 h
6 h
[a]
[b]
[c]
Ratio of ArBr to NCTS is 1.5:1.
Isolated yield.
Yield by 1H NMR (N-phenyl-p-methylbenzenesulfona-
mide was isolated as well).
[d]
[e]
Yield by GC (the corresponding ArH was also present).
ArZnBr formed with [CoBr2(bpy)] instead of CoBr2
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aliquots, until all of the NCTS was consumed (4–6 h). Aque-
ous hydrochloric acid (ca 2M, 20 mL) and Et2O (20 mL)
were then added to the reaction mixture and stirred for
5 min. The phases were separated, and the aqueous phase
was extracted 3 times with Et2O (20 mL). The combined or-
ganic phases were washed with water (20 mL) and brine
(20 mL), dried over MgSO4, and the solvents were evaporat-
ed to afford the crude material, which was purified by
column chromatography (SiO2, petroleum ether/diethyl
ether) affording the corresponding aryl nitrile compound.
functional groups, such as thioether, acetate, chloro,
sulfone, fluoro, trifluoromethyl, dimethylamino, ester,
dioxane provide moderate to excellent yields
(Table 2, entries 6 to 18). However, the presence of
a strong chelating group (ketone or nitrile) on the ar-
ylzinc species inhibits the reaction. As this may be ex-
plained by their chelation to the metal center, we at-
tempted those reactions with [CoBr2(bpy)] instead of
CoBr2 to form the corresponding ArZnBr and were
pleased to observe a reaction. Under these conditions
moderate yields of aryl nitriles were obtained
(Table 2, entries 19–21), the corresponding ArH was
the major product in the reaction mixture. Moreover,
despite several attempts, only poor yields of aryl ni-
trile product were observed from aryl chlorides due
to the presence of the excess of pyridine required to
prepare the corresponding arylzinc chloride, which
hampers the cyanation step.[30] Heteroaryl zinc bro-
mides (thiophene and furyl derivatives) gave only
some traces of the expected nitrile derivatives.
Acknowledgements
We thank the Minist›re de l’Enseignement SupØrieur et de la
Recherche for the PhD grants. This work was supported by
CNRS and Ecole Polytechnique.
References
In summary, this new cobalt-catalyzed cross-cou-
pling of arylzinc compounds with NCTS allows an
easy access to various benzonitriles, and complements
nicely known methodologies. This reaction tolerates
a large number of functional groups and the yields
range from modest to excellent. The presence of a cat-
alytic amount of zinc dust in the coupling reaction is
necessary to achieve good efficiency. The low price of
the catalyst used, and the mild and ꢂbench-friendlyꢀ
conditions for the synthesis of the reagents make this
reaction an interesting alternative to more classical
[1] a) A. J. Fatiadi, in: Preparation and synthetic applica-
tions of cyano compounds, (Eds.: S. Patai, Z. Rappo-
port), Wiley, New York, 1983; b) R. C. Larock, Com-
prehensive organic Transformations, VCH, New York,
1989; c) J. S. Miller, J. L. Manson, Acc. Chem. Res.
2001, 34, 563–570; d) A. Kleemann, J. Engel, B. Kutsch-
er, D. Reichert, Pharmaceutical Substances: Synthesis
Patents, Applications, 4th edn., Thieme, Stuggart, 2001;
e) F. F. Fleming, Q. Z. Wang, Chem. Rev. 2003, 103,
2035–2077; f) M. B. Smith, J. March, Marchꢀs Advanced
Organic Chemistry: Reactions, Mechanisms, and Struc-
ture, 6th edn., Wiley, Hoboken, NJ, 2007.
À
methodologies and C H activation.
[2] a) P. Anbarasan, T. Schareina, M. Beller, Chem. Soc.
Rev. 2011, 40, 5049–5067; b) J. Kim, H. J. Kim, S.
Chang, Angew. Chem. 2012, 124, 12114–12125; Angew.
Chem. Int. Ed. 2012, 51, 11948–11959.
Experimental Section
[3] C. Galli, Chem. Rev. 1988, 88, 765–792.
[4] a) K. W. Rosemund, E. Struck, Ber. Dtsch. Chem. Ges.
A/B 1919, 52, 1749–1756; b) D. T. Mowry, Chem. Rev.
1948, 42, 189–283.
General Procedure for the Synthesis and Cross-
Coupling of Arylzinc Bromides with NCTS
To a solution of CoBr2 (0.5 mmol, 110 mg, 13 mol%) and Zn
dust (10 mmol, 0.65 g, 2.5 equiv.) in MeCN (4 mL) were
added allyl chloride (0.125 mL, 1.5 mmol, 30 mol%) and
TFA (0.05 mL), at room temperature under vigorous stir-
ring. This caused a rise in temperature, production of gases,
and a change of the color of the mixture from blue to
orange to dark grey. Once the orange tinge of the mixture
had disappeared, ArBr (3.75 mmol, 1 equiv.) was added.
The reaction was followed by GC on iodolyzed aliquots.
Once all the starting bromide was consumed, stirring was in-
terrupted; the reaction medium was taken in a 10-mL sy-
ringe, and filtered through a syringe filter providing a solu-
tion of a cobalt-containing arylzinc bromide solution. An in-
ternal standard was added (decane or dodecane), and the
solution was titrated by GC on an iodolyzed aliquot. The ar-
ylzinc was injected into a solution of NCTS (2.5 mmol) and
Zn dust (0.02 g, 0.25 mmol) in acetonitrile which was placed
in a Schlenk flask under N2 and was cooled to 08C. The ice
bath was allowed to melt, and then the mixture was heated
to 508C. The reaction was followed by GC on hydrolyzed
[5] J. Chen, Y. Sun, B. Liu, D. Liu, J. Cheng, Chem.
Commun. 2012, 48, 449–451.
[6] H. J. Cristau, A. Ouali, J. F. Spindler, M. Taillefer,
Chem. Eur. J. 2005, 11, 2483–2492.
[7] A. V. Ushkov, V. V. Grushin, J. Am. Chem. Soc. 2011,
133, 10999–11005.
[8] F. G. Buono, R. Chidambaram, R. H. Mueller, R. E.
Waltermire, Org. Lett. 2008, 10, 5325–5328.
[9] M. Sundermeier, S. Mutyala, A. Zapf, A. Spannenberg,
M. Beller, J. Organomet. Chem. 2003, 684, 50–55.
[10] a) M. Sundermeier, A. Zapf, M. Beller, Angew. Chem.
2003, 115, 1700–1703; Angew. Chem. Int. Ed. 2003, 42,
1661–1664; b) T. Schareina, A. Zapf, A. Cotte, M.
Gotta, M. Beller, Adv. Synth. Catal. 2011, 353, 777–780.
[11] P. Y. Yeung, C. M. So, C. P. Lau, F. Y. Kwong, Org.
Lett. 2011, 13, 648–651.
[12] a) K. V. V. Krishna Mohan, M. N. Narender, S. J. Kul-
karni, Tetrahedron Lett. 2004, 45, 8015–8018; b) X.
Chen, X.-S. Hao, C. E. Goodhue, J.-Q. Yu, J. Am.
Chem. Soc. 2006, 128, 6790–6791; c) J. Kim, S. Chang, J.
3422
asc.wiley-vch.de
ꢁ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2015, 357, 3419 – 3423

COMMUNICATIONS
Cobalt-Catalyzed Electrophilic Cyanation of Arylzinc Halides
Am. Chem. Soc. 2010, 132, 10272–10274; d) X. Ren, J.
Chen, F. Chen, J. Cheng, Chem. Commun. 2011, 47,
6725–6727; e) D. N. Sawant, Y. S. Wagh, P. J. Tambade,
K. D. Bhatte, B. M. Bhanage, Adv. Synth. Catal. 2011,
353, 781–787; f) S. Ding, N. Jiao, J. Am. Chem. Soc.
2011, 133, 12374–12377; g) G. Zhang, X. Ren, J. Chen,
M. Hu, J. Cheng, Org. Lett. 2011, 13, 5004–5007; h) J.
Kim, J. Choi, K. Shin, S. Chang, J. Am. Chem. Soc.
2012, 134, 2528–2531; i) J. Kim, H. Kim, S. Chang, Org.
Lett. 2012, 14, 3924–3927.
Knochel, A. Krasovskiy, in: Handbook of Functional-
ized Organometallics, Vol. 1, (Ed.: P. Knochel), Wiley-
VCH, Weinheim, 2005, pp 109–172; d) F. M. Piller, P.
Appukkuttan, A. Gavryushin, M. Helm, P. Knochel,
Angew. Chem. 2008, 120, 6907–6911; Angew. Chem. Int.
Ed. 2008, 47, 6802–6806.
[21] F. Kurzer, J. Chem. Soc. 1949, 1034–1038.
[22] P. Anbarasan, H. Neumann, M. Beller, Angew. Chem.
2011, 123, 539–542; Angew. Chem. Int. Ed. 2011, 50,
519–522.
[23] a) T.-J. Gong, B. Xiao, W.-M. Cheng, W. Su, J. Xu, Z.-J.
Liu, L. Liu, Y. Fu, J. Am. Chem. Soc. 2013, 135, 10630–
10633; b) J. Han, C. Pan, X. Jia, C. Zhu, Org. Biomol.
Chem. 2014, 12, 8603–8606.
[13] a) N. Sato, Tetrahedron Lett. 2002, 43, 6403–6404; b) N.
Sato, Q. Yue, Tetrahedron 2003, 59, 5831–5836.
[14] Y. Q. Wu, D. C. Limburg, D. E. Wilkinson, G. S. Hamil-
ton, Org. Lett. 2000, 2, 795–797.
[15] a) A. M. van Leuse, A. J. W. Iedema, J. Strating, J.
Chem. Soc. Chem. Commun. 1968, 440–441; b) A. M.
van Leuse, J. C. Jagt, Tetrahedron Lett. 1970, 967–970.
[16] J. S. Koo, J. I. Lee, Synth. Commun. 1996, 26, 3709–
3713.
[24] W. Liu, L. Ackermann, Chem. Commun. 2014, 50,
1878–1881.
[25] Y. Yang, S. L. Buchwald, Angew. Chem. 2014, 126,
8821–8825; Angew. Chem. Int. Ed. 2014, 53, 8677–8681.
[26] J. Li, L. Ackermann, Angew. Chem. 2015, 127, 8671–
8674; Angew. Chem. Int. Ed. 2015, 54, 8551–8554.
[27] Z. Shu, W. Ji, X. Wang, Y. Zhou, Y. Zhang, J. Wang,
Angew. Chem. 2014, 126, 2218–2221; Angew. Chem. Int.
Ed. 2014, 53, 2186–2189.
[17] P. Anbarasan, H. Neumann, M. Beller, Chem. Eur. J.
2010, 16, 4725–4728.
[18] Z. Zhang, L. S. Liebeskind, Org. Lett. 2006, 8, 4331–
4333.
[19] P. Anbarasan, H. Neumann, M. Beller, Chem. Eur. J.
[28] I. Klement, K. Lennick, C. E. Tucker, P. Knochel, Tet-
2011, 17, 4217–4222.
rahedron Lett. 1993, 34, 4623–4626.
[20] a) L. Boymond, M. Rottlander, G. Cahiez, P. Knochel,
Angew. Chem. 1998, 110, 1801–1803; Angew. Chem.
Int. Ed. 1998, 37, 1701–1703; b) P. Knochel, W. Dohle,
N. Gommermann, F. F. Kneisel, F. Kopp, T. Korn, I.
Sapountzis, V. A. Vu, Angew. Chem. 2003, 115, 4438–
4456; Angew. Chem. Int. Ed. 2003, 42, 4302–4320; c) P.
[29] a) X. Qian, Z. Yu, A. Auffrant, C. Gosmini, Chem.
Eur. J. 2013, 19, 6225–6229; b) M. Corpet, X.-Z. Bai, C.
Gosmini, Adv. Synth. Catal. 2014, 356, 2937–2942.
[30] Noteworthy is that the reaction of arylzinc bromide
with NCTS in the presence of pyridine was also less ef-
fective than in absence of this additive.
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