AgONO-Assisted Direct C-H Arylation of Heteroarenes with Anilines

Article abstract of DOI:10.1002/chem.201403640

A novel copper-catalyzed C-H arylation of heteroarenes with anilines by an in situ diazonium reaction is established by using silver nitrite (AgONO) as an unconventional nitrosating reagent under acid-free conditions. It provides a complementary approach for the C-H arylation of electron-rich heteroarenes with aromatic amines affording a variety of heterobiaryls in moderate to good yields.

Full text of DOI:10.1002/chem.201403640

DOI: 10.1002/chem.201403640
Communication
&
CÀH Activation
AgONO-Assisted Direct CÀH Arylation of Heteroarenes with
Anilines
Saravanan Gowrisankar* and Jayasree Seayad*[a]
matic CÀH bonds with aryl diazonium tetrafluoroborates by
Abstract: A novel copper-catalyzed CÀH arylation of het-
merging Pd-catalyzed CÀH activation and Ru-based visible-
eroarenes with anilines by an in situ diazonium reaction is
light photoredox catalysis. Kçnig and co-workers independent-
established by using silver nitrite (AgONO) as an uncon-
ly reported[9] a metal-free variation for the direct CÀH arylation
ventional nitrosating reagent under acid-free conditions. It
of heteroarenes by using Eosin Y as the photoredox catalyst
provides a complementary approach for the CÀH arylation
with aryl diazonium tetrafluoroborates.
of electron-rich heteroarenes with aromatic amines afford-
Alternatively, in situ generation of diazonium salts would
ing a variety of heterobiaryls in moderate to good yields.
elude any erratic safety issues in using prior isolated diazonium
salts. In this regard tert-butylnitrite (tBuONO) has been pro-
posed as an efficient in situ diazotization reagent.[10] Thus,
Heterobiaryls are extremely important motifs in biologically
active molecules, natural products, and materials chemistry.
Their synthesis by direct arylation[1] and oxidative coupling[2]
through CÀH activation has attracted great interest in both
academia and industry lately. From a green chemistry perspec-
tive, these methods are regarded as highly advantageous over
the traditional cross-coupling methods due to the elimination
of the need of prefixing and subsequent removal of reactive
functionalities, hence leading to a decrease in the number of
steps in a given synthesis and thereby minimizing the use and
generation of stoichiometric amounts of hazardous chemicals.
The use of aryl diazonium salts as surrogate electrophiles for
cross-coupling reactions has been receiving increased atten-
tion recently,[3] as they are highly reactive, act as a source of
aryl radicals, and are readily accessible from anilines that are
ubiquitous and inexpensive compared to aryl halides and trif-
lates. The CÀH arylation by using diazonium salts was known
as early as the 1900s, as in the case of Meerwein CÀH aryla-
tion,[4] Pschorr’s cyclization,[5] and Gomberg–Bachmann biaryl
synthesis.[6] However, application of these reactions were re-
stricted because of the poor selectivity and substrate scope in
addition to the difficulty in isolating and handling the highly
unstable and potentially explosive diazonium salts in their crys-
talline form. Nevertheless, further research in this area showed
substantial promise. The problem of the instability of the di-
azonium salts was fairly addressed by developing more stable
diazonium salts with BF4À, PF6À, and OTsÀ as counter ions[7]
and was applied as safer alternatives in various CÀC coupling
reactions including CÀH arylation. For instance, Sanford et al.[8]
demonstrated a directing-group-assisted mild arylation of aro-
recent studies showed that aniline can be directly converted
to aryl boronates,[11] aryl-Sn,[12] aryl-CF3,[13] aryl-N3,[14] aryl ole-
fins,[15] and aryl heteroarenes[16] through in situ diazonium reac-
tions by using tert-butylnitrite (Scheme 1). Recently, Felpin
Scheme 1. New transformations of aniline by an in situ diazotization
reaction.
et al.[16] developed a copper-catalyzed Meerwein CÀH arylation
of pyrroles by in situ generated diazonium salts using tBuONO.
However, this approach was limited to N-Boc-pyrroles. In the
case of electron-rich pyrroles, only an unwanted azo product
was isolated. Very recently, Martin, Carrillo, and co-workers
demonstrated[17] a similar in situ diazonium-based reaction
using tBuONO in combination with ascorbic acid as a free radi-
cal initiator towards a metal-free direct CÀH arylation of
arenes, particularly furans.
[a] Dr. S. Gowrisankar, Dr. J. Seayad
Organic Chemistry, Institute of Chemical and Engineering Sciences (ICES)
8 Biomedical Grove, Neuros #07-01, Singapore 138665
E-mail: jayasree_seayad@ices.a-star.edu.sg
saravanang@ices.a-star.edu.sg
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201403640.
Chem. Eur. J. 2014, 20, 12754 – 12758
12754
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
We report herein a general copper-catalyzed direct CÀH
arylation of electron-rich heterocycles including N-methylpyr-
roles, furans, and thiophenes by using anilines in the presence
of silver nitrite (AgONO) as an alternative diazotization agent
under acid-free conditions. To the best of our knowledge, this
is the first example on the use of AgONO as a diazotization
agent. While AgONO has commonly been used as a nitration
reagent[18] and oxidant,[19] its synthetic applicability as a nitro-
sating agent has never been evaluated in diazonium chemistry.
AgONO is relatively safer to use at elevated temperatures than
tBuONO, which is highly flammable, may readily decompose,
and explodes on heating.[20] Moreover, there are only a few re-
ports on diazotization reactions under acid-free conditions.[11,21]
Our discovery was based on a recent study[22] in our lab on the
RhIII/aniline dual catalysis for the oxidative coupling of alde-
hydes by ortho CÀH activation. While examining different oxi-
dants and solvents for this reaction, we coincidentally ob-
served the formation of traces of biaryl side products, resulting
from a Gomberg–Bachmann-type reaction of the aniline with
the solvent benzene when AgONO was used as the oxidant. In-
spired by this observation, we set out to investigate the possi-
bility of using AgONO as an in situ diazotization reagent in the
Meerwein-type arylation of heteroarenes with anilines.
Table 1. Optimization studies on the CÀH arylation of N-methyl pyrrole
with 2-nitroaniline.
Entry
Catalyst
Additive (equiv)
T [8C]
Yield 3a [%][a,b,c]
1[d]
2
3
4
5
6
7
8
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
CuOAc
CuCl2
Cu2O
CuSO4·5H2O
–
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
Cu(OAc)2
MeSO3H/CaCO3 (1.0)
CH3COOH (1.0)
PivOH (1.0)
CH3COOH (1.0)
PivOH (1.0)
–
–
–
–
–
RT
RT
RT
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
–
–
–
23
42
46
42
44
28
30
–
18
13
32
59
49
62
67
54
9
9
10
11
12
13
14
15
16
17
18
19[e]
20[f]
21[g]
22[h]
–
Cs2CO3(1.0)
K2CO3(1.0)
CaCO3 (1.0)
CsOPiv (0.5)
AgCl (0.5)
LiBr (0.5)
LiBr(0.5)/CsOPiv(0.1)
LiBr(0.5)/CsOPiv(0.1)
LiBr(0.5)/CsOPiv(0.1)
LiBr(0.5)/CsOPiv(0.1)
LiBr(0.5)/CsOPiv(0.1)
We selected the challenging electron-rich N-methylpyrrole
(2a) as the model heteroarene substrate for our initial investi-
gations as it was poorly active towards CÀH arylation when
using the prior methods by diazonium chemistry and was not
well explored.[9,16,17] Accordingly, the reaction of 2a with 2-ni-
troaniline in the presence of tBuONO, using the reported[16]
catalyst system Cu(OAc)2/MeSO3H/CaCO3 resulted merely in the
formation of the diazo product 1-methyl-2-[(2-nitrophenyl)di-
azenyl]-1H-pyrrole (4a) (Table 1, entry 1) with no detectable
CÀH arylation. We then studied the possibility of employing
AgONO as the nitrosating agent for this reaction using
Cu(OAc)2 as the catalyst along with acetic acid (AcOH) or pival-
ic acid (PivOH) as acid additives to facilitate diazotization as
well as CÀH activation. We were delighted to find that these
reactions resulted in significant CÀH arylation forming 1-
methyl-2-(2-nitrophenyl)-1H-pyrrole (3a) (Table 1, entries 4 and
5) selectively at 908C, although there was no conversion of the
substrates at room temperature. Furthermore, to our surprise,
we discovered that the desired product 3a could be attained
in 46% yield even in the absence of any acid additives
(entry 6). We then examined different copper catalysts under
these conditions, but no significant improvement in the per-
formance was observed (entries 7–10). A control reaction in
the absence of any copper catalyst showed no reaction
(entry 11). Subsequently, to improve the yield further, other ad-
ditives were explored. The addition of bases, such as Cs2CO3,
K2CO3, and CaCO3, was not beneficial (entries 12–14). Interest-
ingly, additives, such as LiBr, AgCl, and CsOPiv, showed im-
provement in the yield of 3a, reaching up to 62% in the case
of LiBr (entry 17). Finally, adding 0.1 equivalents of CsOPiv
along with LiBr further improved the yield to 67% (entry 18).
When the reaction time was shortened to 8 h, the yield was re-
duced to 54% (entry 19). Moreover, when tBuONO was used
instead of AgONO under these conditions, the yield of 3a
39
28
[a] Reaction conditions: 1a (1.0 mmol), 2a (10.0 mmol), catalyst
(0.3 mmol), AgONO (1.2 mmol), 908C, 12 h. [b] The yield was measured
1
by H NMR spectroscopic analysis of the crude reaction mixtures by using
CH2Br2 as the internal standard. [c] Traces of 4a and nitrobenzene were
detected by GCMS. [d] tBuONO (1.2 mmol), Cu(OAc)2·H2O (0.3 mmol), ace-
tone/H2O, 12 h.[16] [e] 8 h. [f] tBuONO instead of AgONO, 8 h. [g] N-methyl-
pyrrole (3.0 mmol)/acetone (1 mL). [h] N-methylpyrrole (3.0 mmol)/DMSO
(1 mL).
(9%) dropped dramatically, which indicated the significance of
AgONO for this CÀH arylation (entry 20). It is noteworthy that
this reaction worked well under neat conditions, rather than in
the presence of any solvents (entries 21 and 22). The excess
amount of the heteroarene aided in suppressing the side prod-
uct nitrobenzene formed by reductive deamination.
With the optimal conditions in hand, we examined the
scope of this method for the direct CÀH arylation of N-methyl-
pyrrole with different substituted aryl amines (Scheme 2). In all
these cases, the corresponding C2-arylated pyrrole derivatives
3a–m were formed with high selectivity and moderate to
good isolated yields (35–81%). In general, electron-poor ani-
lines performed better than their electron-rich counter partners
and a range of functional groups (NO2, COOMe, CN, COMe,
CF3, Br, Cl, and OH) were tolerated. Notably, bromo- and
chloro-substituted aniline (3c and 3j–l) successfully underwent
the coupling reaction intact with the CÀBr/CÀCl bond, which
will be useful for further functionalization. The heteroarylation
of N-methylpyrrole with isoquinoline-1-amine produced 1-(1-
methyl-1H-pyrrol-2-yl)isoquinoline (3m) in 20% isolated yield.
The 2-substituted pyrrole derivatives, such as 1-(1-methyl-1H-
pyrrol-2-yl)ethan-1-one and 1-(1H-pyrrol-2-yl)ethan-1-one, also
Chem. Eur. J. 2014, 20, 12754 – 12758
www.chemeurj.org
12755
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
corresponding C2- or C5-arylated products with high selectivi-
ty. It is noteworthy that under the conditions reported herein,
CÀH arylation always occurred selectively at the C2-position on
the simple furan and C5-position on the C2-substituted furan
with no detectable byproducts arising from CÀH arylation at
the other positions. Similar to the case of the pyrroles, the re-
action occurred smoothly with various ortho-, meta-, and para-
substituted anilines, particularly with electron-withdrawing
groups, giving moderate to good yields (51–76%) of the corre-
sponding arylfuran derivatives (6a–m).
Further usefulness of this methodology was demonstrated
by the successful CÀH arylation of thiophenes. Under similar
conditions to that of furans, the coupling reaction of various
thiophene derivatives and anilines took place efficiently to
afford the corresponding aryl thiophenes 8a–l in moderate to
good yields (24–77%; Scheme 4). However, in cases for which
there are two possible reactive sites, as in the case of the un-
substituted thiophene, a minor amount of the C3-arylated
product was also formed.
Scheme 2. CÀH arylation of pyrroles and indoles with anilines. Reaction con-
ditions: 1 (1.0 mmol), 2 (10.0 mmol or 1 mL), Cu(OAc)2 (0.3 mmol), AgONO
(1.2 mmol), CsOPiv (0.1 mmol), LiBr (0.5 mmol), 908C, 12 h. The yields given
are isolated yields. Complete conversion of anilines was observed by TLC
and GCMS analysis. [a] At room temperature. [b] Isolated along with the
corresponding C3-arylated product in a ratio of 9.1:1 [c] N-methylpyrrole
(3.0 mmol)/acetone (1 mL) at 60–708C.
gave the corresponding C5-arylated products (3n–q) selective-
ly in moderate yields (43–65%). Under these conditions,
N-methylindole furnished a 60% yield of the corresponding
C3- (3r) and C2-arylated (3r’) products in a ratio of 1:1.
Next, the CÀH arylation of furan as well as the hitherto less
explored electron-rich C2-substituted furan derivatives, such as
2-methylfuran and furan-2-ylmethyl acetate, with different ani-
lines were investigated (Scheme 3). Remarkably, in all these
cases, the reaction was completed in 8 h at 708C, affording the
Scheme 4. CÀH arylation of thiophenes with anilines: Reaction conditions:
aniline (1.0 mmol), thiophene (10.0 mmol or 1 mL), Cu(OAc)2 (0.3 mmol),
AgONO (1.2 mmol), CsOPiv (0.1 mmol), LiBr (0.5 mmol), 708C, 8 h. The yields
given are total isolated yields of the two regioisomers. Complete conversion
of anilines was observed by TLC and GCMS analysis. [a] Only the C2-arylated
product was observed.
Our preliminary mechanistic investigations on this novel
CÀH arylation by using aniline in the presence of AgONO sug-
gests a radical mechanism analogous to that proposed by
Felpin et al.[16] When 2-nitroaniline (1a) or 2-aminomethyl ben-
zoate (1b) and AgONO were reacted in the presence of the
radical
scavenger
2,2,6,6-tetramethyl-1-piperidin-1-oxyl
(TEMPO), the corresponding O-aryl-TEMPO adducts (10a and
10b) were trapped and detected by GCMS analysis
(Scheme 5a) confirming the generation of the corresponding
aryl radicals. Interestingly, we have also isolated and character-
ized a C-nitroso pyrrole adduct 11 by the reaction of 1b with
N-methylpyrrole (Scheme 5b), which perhaps is formed by the
reaction of the radical intermediate III-b with AgONO.[23] Thus,
Scheme 3. CÀH arylation of furans with anilines: Reaction conditions: aniline
(1.0 mmol), furan (10.0 mmol or 1 mL), Cu(OAc)2 (0.3 mmol), AgONO
(1.2 mmol), CsOPiv (0.1 mmol), LiBr (0.5 mmol), 708C, 8 h. The yields given
are for the isolated product. Complete consumption of anilines was
observed by TLC and GCMS analysis.
Chem. Eur. J. 2014, 20, 12754 – 12758
www.chemeurj.org
12756
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
Acknowledgements
The project was supported by the GSK–Singapore partnership
for green and sustainable manufacturing.
Keywords: CÀH arylation
· copper acetate · diazonium
reaction · heteroarenes · silver nitrite
[1] For selected reviews and highlights on the direct arylation of hetero-
arenes, see: a) F. Shibahara, T. Murai, Asian J. Org. Chem. 2013, 2, 624–
636; b) J. J. Mousseau, A. B. Charette, Acc. Chem. Res. 2012, 45, 412–
424; c) C. Fischmeister, H. Doucet, Green Chem. 2011, 13, 741–753; d) C.
Verrier, P. Lassalas, L. Thꢁveau, G. Quguiner, F. Trꢁcourt, F. Marsais, C.
Hoarau, Beilstein J. Org. Chem. 2011, 7, 1584–1601; e) J. Wencel-Delord,
T. Drçge, F. Liu, F. Glorius, Chem. Soc. Rev. 2011, 40, 4740–4761; f) L. Ac-
kermann, Chem. Rev. 2011, 111, 1315–1345; g) J. Roger, A. L. Gottumuk-
kala, H. Doucet, ChemCatChem 2010, 2, 20–40; h) S. Messaoudi, J.-D.
Brion, M. Alami, Eur. J. Org. Chem. 2010, 6495–6516; i) D. A. Colby, R. G.
Bergman, J. A. Ellman, Chem. Rev. 2010, 110, 624–655; j) L. Ackermann,
R. Vicente, Top. Curr. Chem. 2010, 292, 211–229; k) F. Bellina, R. Rossi,
Tetrahedron 2009, 65, 10269–10310; l) L. Ackermann, R. Vicente, A. R.
Kapdi, Angew. Chem. 2009, 121, 9976–10011; Angew. Chem. Int. Ed.
2009, 48, 9792–9826; m) L.-C. Campeau, D. R. Stuart, K. Fagnou, Aldri-
chimica Acta 2007, 40, 35–41; n) D. Alberico, M. E. Scott, M. Lautens,
Chem. Rev. 2007, 107, 174–238; o) I. V. Seregin, V. Gevorgyan, Chem.
Soc. Rev. 2007, 36, 1173–1193; p) L.-C. Campeau, K. Fagnou, Chem.
Commun. 2006, 1253–1264; q) M. Miura, M. Nomura, Top. Curr. Chem.
2002, 219, 211–241.
[2] For selected reviews and highlights on the CÀH activation of hetero-
arenes, see: a) S. R. Neufeldt, M. S. Sanford, Acc. Chem. Res. 2012, 45,
936–946; b) T. Brꢂckl, R. D. Baxter, Y. Ishihara, P. S. Baran, Acc. Chem. Res.
2012, 45, 826–839; c) S. H. Cho, J. Y. Kim, J. Kwak, S. Chang, Chem. Soc.
Rev. 2011, 40, 5068–5083; d) C. S. Yeung, V. M. Dong, Chem. Rev. 2011,
111, 1215–1292; e) L. McMurray, F. O’Hara, M. J. Gaunt, Chem. Soc. Rev.
2011, 40, 1885–1898; f) K. Hirano, M. Miura, Synlett 2011, 294–307;
g) D. Zhao, J. You, C. Hu, Chem. Eur. J. 2011, 17, 5466–5492; h) K.
Fagnou, Top. Curr. Chem. 2010, 292, 35–56; i) S. H. Cho, J. Y. Kim, J.
Kwak, S. Chang, Chem. Soc. Rev. 2011, 40, 5068–5083; j) D. Zhao, J. You,
C. Hu, Chem. Eur. J. 2011, 17, 5466–5492; k) W. Han, A. R. Oal, Synlett
2011, 1951–1955; l) X. Bugaut, F. Glorius, Angew. Chem. 2011, 123,
7618–7620; Angew. Chem. Int. Ed. 2011, 50, 7479–748; m) K. Fagnou,
Top. Curr. Chem. 2009, 292, 35–56; n) S.-L. You, J.-B. Xia, Top. Curr.
Scheme 5. Mechanistic studies.
the catalytic cycle involves a CuI-mediated homolytic dediazo-
niation of the in situ generated aryldiazonium salt, from the
aniline and AgONO, affording the aryl radical I, which is rapidly
captured by the heteroarene forming the radical intermediate
II. The CuII catalyst then oxidizes the radical intermediate II to
the heterobiaryl products (3, 6, and 8) by regenerating the
active CuI species. Nevertheless, further studies are necessary
to understand the complete mechanism.
Conclusion
We have developed a copper-catalyzed method for the CÀH
arylation of heteroarenes with anilines by an in situ diazonium
reaction using silver nitrite as an unusual nitrosating agent
under acid-free conditions. The CÀH arylation proceeds
smoothly at 70–908C, and displays a broad substrate scope to-
wards electron-rich pyrroles, furans, and thiophenes with excel-
lent functional-group tolerance. Further studies directed to-
wards understanding the mechanism of this reaction and ex-
tending the application of this AgONO-based in situ diazonium
reaction for other coupling reactions are underway.
ˇ
Chem. 2009, 292, 165–194; o) G. B. Shulpin, Org. Biomol. Chem. 2010, 8,
4217–4228; p) T. W. Lyons, M. S. Sanford, Chem. Rev. 2010, 110, 1147–
1169.
[3] For selected reviews and highlights on the diazonium cross-coupling,
see a) H. Bonin, M. Sauthier, F.-X. Felpin, Adv. Synth. Catal. 2014, 356,
645–671; b) F. Mo, G. Dong, Y. Zhang, J. Wang, Org. Biomol. Chem.
2013, 11, 1582–1593; c) D. P. Hari, B. Kçnig, Angew. Chem. 2013, 125,
4832–4842; Angew. Chem. Int. Ed. 2013, 52, 4734–4743; d) H. Bonin, E.
Fouquet, F.-X. Felpin, Adv. Synth. Catal. 2011, 353, 3063–3084; e) A. Ro-
glans, A. Pla-Quintana, M. Moreno-MaÇas, Chem. Rev. 2006, 106, 4622–
4643.
[4] H. Meerwein, E. Buchner, K. van Emsterk, J. Prakt. Chem. 1939, 152,
237–266.
[5] R. Pschorr, Ber. Dtsch. Chem. Ges. 1896, 29, 496–501.
Experimental Section
[6] M. Gomberg, W. E. Bachmann, J. Am. Chem. Soc. 1924, 46, 2339–2343.
[7] For reviews on different diazonium salts as counter anions, see: a) N.
Zhang, S. R. Samanta, B. M. Rosen, V. Percec, Chem. Rev. 2014, 114,
5848–5958; b) C. Galli, Chem. Rev. 1988, 88, 765–792; c) T. I. Godoviko-
va, O. A. Rakitin, L. I. Khmelnitskii, Russ. Chem. Rev. 1983, 52, 440–445.
[8] D. Kalyani, K. B. McMurtrey, S. R. Neufeldt, M. S. Sanford, J. Am. Chem.
Soc. 2011, 133, 18566–18569.
[9] D. P. Hari, P. Schroll, B. Kçnig, J. Am. Chem. Soc. 2012, 134, 2958–2961.
[10] For representative examples on in situ generated aryl diazonium salts
by using tert-butylnitrite, see a) D. Qiu, L. Jin, Z. Zheng, H. Meng, F. Mo,
X. Wang, Y. Zhang, J. Wang, J. Org. Chem. 2013, 78, 1923–1933; b) A.
Honraedt, F. L. Callonnec, E. L. Grognec, V. Fernandez, F.-X. Felpin, J. Org.
General procedure for the CÀH arylation
An oven-dried 8 mL reaction vial was charged with Cu(OAc)2
(54 mg, 0.3 mmol, 30 mol%), AgONO (185 mg, 1.2 mmol), LiBr
(43 mg, 0.5 mmol), CsOPiv (24 mg, 0.1 mmol), aniline (1.0 mmol),
and the heteroarene (10.0 mmol) in open air. The vial was sealed
with a septum and the reaction mixture was stirred at 70–908C for
8–12 h. The crude reaction mixture was filtered through a pad of
magnesium sulfate, the filtrate concentrated under reduced pres-
sure and the crude product was purified by flash chromatography.
Chem. Eur. J. 2014, 20, 12754 – 12758
www.chemeurj.org
12757
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
Chem. 2013, 78, 4604–4609; c) R. Joncour, N. Susperregui, N. Pinaud, K.
Miqueu, E. Fouquet, J.-M. Sotiropoulos, F.-X. Felpin, Chem. Eur. J. 2013,
19, 9291–9296; d) M. Lamblin, G. Naturale, J. Dessolin, F.-X. Felpin, Syn-
lett 2012, 1621–1624; e) N. Susperregui, K. Miqueu, J-M. Sotiropoulos,
F. L. Callonnec, E. Fouquet, F.-X. Felpin, Chem. Eur. J. 2012, 18, 7210–
7218; f) X.-F. Wu, H. Neumann, M. Beller, Chem. Commun. 2011, 47,
7959–7961; g) F. L. Callonnec, E. Fouquet, F.-X. Felpin, Org. Lett. 2011,
13, 2646–2649; h) B. Schmidt, F. Hçlter, R. Berger, S. Jessel, Adv. Synth.
Catal. 2010, 352, 2463–2473; i) M. B. Andrus, C. Song, J. Zhang, Org.
Lett. 2002, 4, 2079–2082.
[16] A. Honraedt, M.-A. Raux, E. L. Grognec, D. Jacquemina, F.-X. Felpin,
Chem. Commun. 2014, 50, 5236–5238.
[17] F. P. Crisꢃstomo, T. Martꢄn, R. Carrillo, Angew. Chem. 2014, 126, 2213–
2217; Angew. Chem. Int. Ed. 2014, 53, 2181–2185.
[18] a) S. Maity, S. Manna, S. Rana, T. Naveen, A. Mallick, D. Maiti, J. Am.
Chem. Soc. 2013, 135, 3355–3358; b) Y-K. Liu, S.-J. Lou, D.-Q. Xu, Z.-Y.
Xu, Chem. Eur. J. 2010, 16, 13590–13593; c) R. Ballini, L. Barboni, G.
Giarlo, J. Org. Chem. 2004, 69, 6907–6908.
[19] a) B. Morandi, Z. K. Wickens, R. H. Grubbs, Angew. Chem. 2013, 125,
9933–9936; Angew. Chem. Int. Ed. 2013, 52, 9751–9754; b) J.-M. Weibel,
A. Blanc, P. Pale, Chem. Rev. 2008, 108, 3149–3173.
[20] a) R. Fortt, R. C. R. Wootton, A. J. de Mello, Org. Process Res. Dev. 2003, 7,
762–768; b) M. P. Doyle, B. Siegfried, J. F. Dellaria, Jr., J. Org. Chem.
1977, 42, 2426–2431; c) MSDS of tBuONO (Chemwatch 2351-2, Cat. No:
N0357, TCI-America and Product. No: 235385, Sigma–Aldrich).
[21] M. E. Trusova, E. A. Krasnokutskaya, P. S. Postnikov, Y. Choi, K.-W. Chi,
V. D. Filimonov, Synthesis 2011, 2154–2158.
[22] P. W. Tan, N. A. B. Juwaini, J. Seayad, Org. Lett. 2013, 15, 5166–5169.
[23] a) H. Vancˇik, Aromatic C-Nitroso Compounds, Springer, Heidelberg, 2013;
b) B. G. Gowenlock, G. B. Richter-Addo, Chem. Rev. 2004, 104, 3315–
3340.
[11] F. Mo, Y. Jiang, D. Qiu, Y. Zhang, J. Wang, Angew. Chem. 2010, 122,
1890–1893; Angew. Chem. Int. Ed. 2010, 49, 1846–1849.
[12] D. Qiu, H. Meng, L. Jin, S. Wang, S. Tang, X. Wang, F. Mo, Y. Zhang, J.
Wang, Angew. Chem. 2013, 125, 11795–11798; Angew. Chem. Int. Ed.
2013, 52, 11581–11584.
[13] a) J.-J. Dai, C. Fang, B. Xiao, J. Yi, J. Xu, Z.-J. Liu, X. Liu, L. Liu, Y. Fu, J.
Am. Chem. Soc. 2013, 135, 8436–8439; b) X. Wang, Y. Xu, F. Mo, G. Ji, D.
Qiu, J. Feng, Y. Ye, S. Zhang, Y. Zhang, J. Wang, J. Am. Chem. Soc. 2013,
135, 10330–10333.
[14] a) K. Barral, A. D. Moorhouse, J. E. Moses, Org. Lett. 2007, 9, 1809–1811;
b) J. Das, S. N. Patil, R. Awasthi, C. P. Narasimhulu, S. Trehan, Synthesis
2005, 1801–1806; c) L. Marinescu, J. Thinggaard, I. B. Thomsen, M. Bols,
J. Org. Chem. 2003, 68, 9453–9455.
[15] For reviews, see: a) F.-X. Felpin, L. Nassar-Hardy, F. Le Callonnec, E. Fou-
quet, Tetrahedron 2011, 67, 2815–2831; b) J. G. Taylor, A. V. Moro,
C. R. D. Correia, Eur. J. Org. Chem. 2011, 1403–1428.
Received: May 22, 2014
Published online on August 18, 2014
Chem. Eur. J. 2014, 20, 12754 – 12758
www.chemeurj.org
12758
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim