Rhodium(III)-catalyzed oxidative olefination of N-(naphthalen-1-yl)amides

Article abstract of DOI:10.1055/s-0031-1290428

Rhodium(III)-catalyzed oxidative coupling of N-(naphthalen-1-yl)amides with acrylates and styrene was achieved through selective C-H bond activation at the peri position. This reaction proceeded smoothly to give the direct olefination product or the corre

Full text of DOI:10.1055/s-0031-1290428

LETTER
▌1649
lRetther odium(III)-Catalyzed Oxidative Olefination of N-(Naphthalen-1-yl)amides
Oxidative Olefination of N-(Naphthalen-1-yl)amides
Xiaowei Wang,a,b,c Xuting Li,b Jian Xiao,b Yi Jiang,*a Xingwei Li*b
a
Chengdu Institute of Organic Chemistry, The Chinese Academy of Sciences, Chengdu 610041, P. R. of China
b
Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, Dalian 116023, P. R. of China
c
Graduate University of Chinese Academy of Sciences, The Chinese Academy of Sciences, Beijing 100049, P. R. of China
E-mail: yjiang@cioc.ac.cn; E-mail: xwli@dicp.ac.cn
Received: 10.03.2012; Accepted after revision: 02.04.2012
We initiated our studies with the coupling between N-
Abstract: Rhodium(III)-catalyzed oxidative coupling of N-(naph-
(naphthalen-1-yl)acetamide 1a and benzyl acrylate
thalen-1-yl)amides with acrylates and styrene was achieved through
(Scheme 1). Our initial screening indicated that the de-
sired product 3a was isolated in 42% yield when a combi-
selective C–H bond activation at the peri position. This reaction
proceeded smoothly to give the direct olefination product or the cor-
responding olefination–cyclization product. High functional-group nation of [RhCp*Cl2]2 (4 mol%) and Cu(OAc)2 (2 equiv)
tolerance was observed
was used (MeCN, 125 °C). Gratifyingly, the yield of the
3a was increased to 88% when Ag2CO3 (2 equiv) was
used as an oxidant (MeCN, 115 °C). Cyclic product 3a ex-
ists as a mixture of two rotational isomers in the solution
state, as a result of hindered rotation along the N–C(O)
bond, and this observation agrees with a related report.12
Formation of product 3a is proposed to result from oxida-
tive olefination of N-(naphthalen-1-yl)acetamide at the
peri position, followed by intramolecular hydroamination
(aza-Michael addition).
Keywords: oxidative olefination, C–H activation, rhodium
Metal-catalyzed direct C–H bond activation and oxidative
functionalization with alkenes (the Fujiwara–Moritani re-
action) has emerged as a powerful tool for C–C bond for-
mation.1 With no necessity of substrate preactivation, the
usefulness of this reaction has been elegantly demonstrat-
ed in the total synthesis of natural products.2 Palladium
catalysts have been widely used for this reaction,3 with
some reports using other metals such as ruthenium.4
O
O
OBn
H
HN
Me
+
Recently, Rh(III) catalysts have stood out in the C–H ac-
tivation of arenes with high functional-group tolerance
and with unique reactivity and selectivity; and this area
has attracted much attention.5 In most cases, a directing
group is necessary to effect high selectivity, and the di-
recting groups include hydroxyl, carbonyl, amide, imine,
pyrazole, and pyridine. Amides are widely present and are
important building blocks in organic synthesis. Given the
availability and the chelation effect of an amide group, ox-
idative C–H functionalization of amide-functionalized
arenes has been extensively studied. Recently, Miura and
Satoh,6 Glorius,7 Fagnou,8 Rovis,9 and we10 have made
some progress in rhodium-catalyzed oxidative coupling
reactions utilizing amide or amidine as a directing group.
In particular, we recently reported Rh(III)-catalyzed oxi-
dative coupling of N-(1-naphthyl)sulfonamides with al-
kenes at the peri position.11 The olefination of a related
carboxamide substrate was only briefly studied by one of
us.11 In addition, the marginally related amide-functional-
ized biphenyls have been reported to couple with olefins
under palladium catalysis.12 Noting that achieving C–H
activation assisted by readily installable directing groups
should serve to expand the synthetic utility of Rh(III)-cat-
alyzed coupling reactions, we now report a general meth-
od of the selective olefination of N-(naphthalen-1-
yl)carboxamide.
[RhCp*Cl2]2 (4 mol%)
NAc
CO2Bn
Ag2CO3 (2 equiv)
MeCN, 115 °C
1a
2a
3a
Scheme 1 Oxidative olefination of N-(naphthalen-1-yl)acetamide
1a with benzyl acrylate
To explore the substrate scope, we first examined various
N-(naphthalen-1-yl)amides in the reaction with different
acrylates (Scheme 2).13 This oxidative coupling reaction
proceeded efficiently to produce the cyclization products
3a–h in good yields (43–89%). Thus N-(naphthalen-1-
yl)acetamides react with various acrylates such as benzyl
acrylate, n-butyl acrylate, and tert-butyl acylate to give
the desired products in high yields 3a–c. Different substit-
uents in the aromatic ring are tolerated although lower iso-
lated yields tend to be observed for substituted substrates
3d–f. The halide functional group is also well tolerated
(3d), with no Heck coupling or protodehalogenation prod-
ucts being detected. Sterically hindered substrates such as
N-(naphthalen-1-yl)propionamide and N-(naphthalen-1-
yl)isobutyramide can also afford the desired products 3g
and 3h in 52% and 71% yield, respectively. In contrast,
when N-(naphthalen-1-yl)pivalamide was used, this reac-
tion stopped after the olefination stage, with no further
aza-Michael product being detected.11 The effect of this
amide directing group might be ascribed to steric effects.
SYNLETT 2012, 23, 1649–1652
Advanced online publication: 13.06.2012
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
DOI: 10.1055/s-0031-1290428; Art ID: ST-2012-W0220-L
© Georg Thieme Verlag Stuttgart · New York

1650
X. Wang et al.
LETTER
Other activated olefins such as acrylonitrile, however,
were not active enough under our conditions.
HO
O
OBn
LiAlH4 (5 equiv)
r.t., 3 h
N
NAc
EWG
O
O
R1
+
N
R1
H
HN
3a
3aa, 69%
[RhCp*Cl2]2 (4 mol%)
EWG
O
Ot-Bu
HO
Ag2CO3 (2 equiv)
MeCN, 115 °C
O
N
R3
R3
LiAlH4 (5 equiv)
r.t., 3 h
R2
R2
Et
N
1
2
3
O
OnBu
NAc
O
OBn
O
Ot-Bu
3g
3gg, 63%
NAc
NAc
Scheme 3 Reduction of coupled products
R4
3a, 88%
Ot-Bu
3b, 85%
O Ot-Bu
3c, 89%
Ot-Bu
O
O
O
O
H
HN
R1
HN
R1
[RhCp*Cl2]2 (4 mol%)
NAc
NAc
NAc
R4
+
MeO
Ag2CO3 (2 equiv)
MeCN, 115 °C
R3
R3
R2
R2
1
4
5
OMe
Br
3d, 67%
3e, 52%
3f, 43%
Cl
Me
O
Ot-Bu
O
Ot-Bu
O
O
Et
i-Pr
Ph
N
N
NHAc
NHAc
NHAc
3g, 52%
3h, 71%
5a, 89%
5b, 62%
5c, 58%
Scheme 2 Oxidative olefination of N-(naphthalen-1-yl)amide with
acrylates. Reagents and conditions: amide (0.54 mmol), acrylate
(1.08 mmol), [RhCp*Cl2]2 (0.0216 mmol), Ag2CO3 (1.08 mmol),
MeCN (3 mL), 115 °C, 16 h, N2 atmosphere. The indicated yields are
isolated yields.
Ph
Ph
NHAc
NHAc
NHAc
MeO
The isolated products such as 3a and 3g can be efficiently
reduced to the corresponding amine alcohol 3aa and 3gg
in 69% and 63% yield, respectively (Scheme 3).
OMe
5f, 65%
5d, 73%
5e, 33%
Ph
Next we expanded the scope of the olefin to styrenes. Our
results showed that N-(naphthalen-1-yl)acetamides can
react with various styrenes (Scheme 4) and only simple
olefination occurred. Thus styrenes bearing electron-do-
nating and electron-withdrawing groups are viable in this
reaction. It is important that a halide functional group both
in the N-(naphthalen-1-yl)acetamide 5g and in the styrene
substrate 5c is consistently tolerated. In addition, N-(7-
methoxynaphthalen-1-yl)acetamide 1c led to product 5e
in only 33% isolated yield, in line with the relatively low-
er yield synthesis of 3e (Scheme 2). This might be as-
cribed to steric hindrance in addition to the unfavorable
electronic effects with the introduction of an OMe group
into the 7-position.
Ph
O
NHAc
HN
Et
Br
5g, 71%
5h, 76%
Scheme 4 Oxidative olefination of N-(naphthalen-1-yl)amides with
styrenes. Reagents and conditions: amide (0.54 mmol), styrenes (1.08
mmol), [RhCp*Cl2]2 (0.0216 mmol), Ag2CO3 (1.08 mmol), MeCN (3
mL), 115 °C, 16 h, N2 atmosphere. The indicated yields are isolated
yields.
Synlett 2012, 23, 1649–1652
© Georg Thieme Verlag Stuttgart · New York

LETTER
Oxidative Olefination of N-(Naphthalen-1-yl)amides
1651
(4) Weissman, H.; Song, X.; Milstein, D. J. Am. Chem. Soc.
2000, 123, 337.
Under the standard conditions, 1a efficiently underwent
coupling with allylbenzene to give 6a in 85% yield, with
no simple olefination product being isolable (Scheme 5).
As expected, bromine substrate 6b was also obtained in
moderate yield (43%), with no Heck product being ob-
served. In line with previous reports,10d,11,14 we reason that
this reaction might undergo direct olefination, followed
by allylic C–H activation (leading to a rhodium(III) η3-al-
lyl species) and nucleophilic C–N bond formation. Alter-
natively, a rhodium(III)-mediated Wacker-type amidation
followed by β-hydrogen elimination might also be opera-
ble.11
(5) (a) Colby, D. A.; Bergman, R. G.; Ellman, J. A. Chem. Rev.
2009, 110, 624. (b) Satoh, T.; Miura, M. Chem.–Eur. J.
2010, 16, 11212. (c) Song, G.; Wang, F.; Li, X. Chem. Soc.
Rev. 2012, 41, 3651. (d) Zhu, C.; Wang, R.; Falck, J. R.
Chem.–Asian J. 2012, in press; DOI: 10.1002/asia.201200035.
(6) Mochida, S.; Umeda, N.; Hirano, K.; Satoh, T.; Miura, M.
Chem. Lett. 2010, 39, 744.
(7) (a) Besset, T.; Kuhl, N.; Patureau, F. W.; Glorius, F. Chem.–
Eur. J. 2011, 17, 7167. (b) Patureau, F. W.; Besset, T.;
Glorius, F. Angew. Chem. Int. Ed. 2011, 50, 1064.
(c) Patureau, F. W.; Glorius, F. J. Am. Chem. Soc. 2010, 132,
9982. (d) Wencel-Delord, J.; Nimphius, C.; Patureau, F. W.;
Glorius, F. Angew. Chem. Int. Ed. 2012, 51, 2247.
(e) Wencel-Delord, J.; Nimphius, C.; Patureau, F. W.;
Glorius, F. Chem.–Asian J. 2012, in press; DOI:
10.1002/asia.201101018. (f) Rakshit, S.; Grohmann, C.;
Besset, T.; Glorius, F. J. Am. Chem. Soc. 2011, 133, 2350.
(8) (a) Huestis, M. P.; Chan, L.; Stuart, D. R.; Fagnou, K.
Angew. Chem. 2011, 123, 1374. (b) Rakshit, S.; Patureau,
F. W.; Glorius, F. J. Am. Chem. Soc. 2010, 132, 9585.
(c) Stuart, D. R.; Bertrand-Laperle, M. G.; Burgess, K. M.
N.; Fagnou, K. J. Am. Chem. Soc. 2008, 130, 16474.
(9) (a) Du, Y.; Hyster, T. K.; Rovis, T. Chem. Commun. 2011,
47, 12074. (b) Hyster, T. K.; Rovis, T. J. Am. Chem. Soc.
2010, 132, 10565. (c) Hyster, T. K.; Rovis, T. Chem. Sci.
2011, 2, 1606.
Ph
H
NHAc
NAc
[RhCp*Cl2]2 (4 mol%)
Ph
(2 equiv)
+
Ag2CO3 (2 equiv)
MeCN 115 °C
R
6a, R = H, 85%
6b, R = Br, 43%
R
Scheme 5 Reaction of N-(naphthalen-1-yl)acetamides with allyl-
benzene
(10) (a) Song, G.; Chen, D.; Pan, C.-L.; Crabtree, R. H.; Li, X.
J. Org. Chem. 2010, 75, 7487. (b) Song, G.; Gong, X.; Li, X.
J. Org. Chem. 2011, 76, 7583. (c) Su, Y.; Zhao, M.; Han, K.;
Song, G.; Li, X. Org. Lett. 2010, 12, 5462. (d) Wang, F.;
Song, G.; Du, Z.; Li, X. J. Org. Chem. 2011, 76, 2926.
(e) Wang, F.; Song, G.; Li, X. Org. Lett. 2010, 12, 5430.
(f) Wei, X.; Zhao, M.; Du, Z.; Li, X. Org. Lett. 2011, 13,
4636.
(11) Li, X.; Gong, X.; Zhao, M.; Song, G.; Deng, J.; Li, X. Org.
Lett. 2011, 13, 5808.
(12) Kim, B. S.; Jang, C.; Lee, D. J.; Youn, S. W. Chem.–Asian
J. 2010, 5, 2336.
In summary, we have developed Rh(III)-catalyzed oxida-
tive coupling of N-(naphthalen-1-yl)amides with acrylates
and styrenes. This methodology showed a wide substrate
scope for both amides and alkenes. It is noteworthy that
halide functional groups were tolerated both in the naph-
thyl ring and in the styrene substrate. The high compati-
bility and versatile reactivity of this transformation may
find wide applications in the synthesis of related struc-
tures.
(13) Typical Procedure of Olefination Reactions
A pressure tube was charged with Ag2CO3 (297 mg, 1.08
mmol, 2 equiv), [RhCp*Cl2]2 (13.3 mg, 0.0216 mmol, 4
mol%), and 1a (100 mg, 0.54 mmol, 1 equiv). After purging
with nitrogen, MeCN (3 mL) and 2c (138 mg, 1.08 mmol, 2
equiv) were added. The tube was sealed, and the mixture was
stirred at 115 °C for 16 h, followed by diluting with CH2Cl2
and filtration through Celite. All volatiles were removed
under reduced pressure. The purification was performed by
flash column chromatography on silica gel using EtOAc in
PE to give 3c (yield 89%).
Acknowledgment
We are grateful to the National Natural Science Foundation of Chi-
na (No. 21072188) and Dalian Institute of Chemical Physics, Chi-
nese Academy of Sciences for financial support. X.L. conceived
and designed all the experiments.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synlett.SnoIufproig
m
iotSrat
ungIifoop
r
t
Spectral Data
Compound 3c (major isomer): 1H NMR (500 MHz, CDCl3):
δ = 7.66 (d, J = 8.2 Hz, 1 H), 7.58–7.47 (m, 1 H), 7.42 (s, 2
H), 7.39–7.32 (m, 1 H), 6.97 (s, 1 H), 6.03 (s, 1 H), 3.25 (d,
J = 14.8 Hz, 1 H), 2.99–2.85 (m, 1 H), 2.54 (s, 3 H), 1.19 (s,
9 H). 13C NMR (126 MHz, CDCl3): δ = 169.48, 168.64,
141.86, 138.77, 131.64, 129.96, 128.59, 128.32, 123.53,
119.07, 117.65, 107.05, 80.63, 62.67, 40.33, 27.75, 25.41.
ESI-HRMS: m/z calcd for [C19H21NO3 + H]+: 312.1599;
found: 312.1592.
References
(1) (a) Jia, C.; Kitamura, T.; Fujiwara, Y. Acc. Chem. Res 2001,
34, 633. (b) Fujiwara, Y.; Moritani, I.; Matsuda, M.;
Teranishi, S. Tetrahedron Lett. 1968, 9, 633. (c) Moritanl, I.;
Fujiwara, Y. Tetrahedron Lett. 1967, 8, 1119.
(2) (a) Baran, P. S.; Corey, E. J. J. Am. Chem. Soc. 2002, 124,
7904. (b) Beck, E. M.; Hatley, R.; Gaunt, M. J. Angew.
Chem. Int. Ed. 2008, 47, 3004. (c) Cushing, T. D.; Sanz-
Cervera, J. F.; Williams, R. M. J. Am. Chem. Soc. 1993, 115,
9323. (d) Garg, N. K.; Caspi, D. D.; Stoltz, B. M. J. Am.
Chem. Soc. 2004, 126, 9552. (e) Trost, B. M.; Godleski,
S. A.; Genet, J. P. J. Am. Chem. Soc. 1978, 100, 3930.
(3) (a) Wencel-Delord, J.; Dröge, T.; Liu, F.; Glorius, F. Chem.
Soc. Rev. 2011, 40, 4740. (b) Yeung, C. S.; Dong, V. M.
Chem. Rev. 2011, 111, 1215.
Compound 5a: 1H NMR (500 MHz, DMSO): δ = 9.90 (s, 1
H), 8.10 (d, J = 16.0 Hz, 1 H), 7.95–7.84 (m, 2 H), 7.62 (d,
J = 7.4 Hz, 2 H), 7.55–7.46 (m, 3 H), 7.40 (t, J = 7.7 Hz, 2
H), 7.33 (d, J = 7.2 Hz, 1 H), 7.27 (t, J = 7.3 Hz, 1 H), 6.75
(d, J = 16.0 Hz, 1 H), 1.82 (s, 3 H). 13C NMR (126 MHz,
DMSO): δ = 169.37, 137.95, 135.82, 135.47, 134.54,
© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 1649–1652

1652
X. Wang et al.
LETTER
130.87, 129.35, 129.27, 129.16, 129.05, 128.24, 128.01,
127.91, 127.65, 126.83, 126.12, 126.04, 23.49. ESI-HRMS:
m/z calcd for [C20H17NO + H]+: 288.1388; found: 288.1394.
Compound 6a: 1H NMR (500 MHz, CDCl3): δ = 8.01 (d, J =
7.1 Hz, 1 H), 7.68 (d, J = 8.2 Hz, 1 H), 7.53–7.43 (m, 3 H),
7.40–7.16 (m, 6 H), 6.81 (d, J = 15.8 Hz, 1 H), 6.22 (dd, J =
15.8, 8.3 Hz, 1 H), 6.06 (d, J = 8.2 Hz, 1 H), 2.40 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 169.68, 142.73, 138.26,
135.72, 132.02, 131.33, 129.60, 129.08, 128.78, 128.44,
128.09, 127.18, 126.71, 123.96, 119.33, 117.29, 110.84,
69.33, 24.43. ESI-HRMS: m/z calcd for [C21H17NO + H]+:
300.1388; found: 300.1382.
Compound 3gg: 1H NMR (500 MHz, CDCl3): δ = 7.52 (d,
J = 8.4 Hz, 1 H), 7.43–7.38 (m, 1 H), 7.29–7.24 (m, 1 H),
7.11 (dd, J = 6.9, 1.4 Hz, 1 H), 6.95 (d, J = 8.2 Hz, 1 H), 6.24
(d, J = 7.2 Hz, 1 H), 5.07 (m, 1 H), 3.72–3.59 (m, 2 H), 3.49–
3.38 (m, 1 H), 3.33 (dd, 1 H), 2.38–2.29 (m, 1 H), 2.27–2.18
(m, 1 H), 1.72–1.67 (m, 2 H), 0.98 (t, J = 7.4 Hz, 3 H).
13C NMR (126 MHz, CDCl3): δ = 151.86, 141.90, 132.01,
130.29, 129.90, 127.85, 122.84, 115.80, 112.05, 97.57,
65.99, 59.05, 48.06, 35.33, 20.90, 11.74. ESI-HRMS:
m/z calcd for [C16H19NO + H]+: 242.1545; found: 242.1549.
(14) Tsai, A. S.; Brasse, M.; Bergman, R. G.; Ellman, J. A. Org.
Lett. 2011, 13, 540.
Synlett 2012, 23, 1649–1652
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