Efficient two-step access to azafluorenones and related compounds

Article abstract of DOI:10.1016/j.tetlet.2013.04.020

Crystals of a lithiocuprate prepared from copper(I) chloride and lithium 2,2,6,6-tetramethylpiperidide (2 equiv) were isolated and analyzed by X-ray diffraction as (TMP)₂Cu(Cl)Li₂·THF. The observation of this species is consistent with its having a role in deprotocupration- aroylation. Phenyl pyridyl ketones, phenyl quinolyl ketones, and phenyl thienyl ketones were prepared in tetrahydrofuran using the lithiocuprate and aroyl chorides as electrophiles. Diaryl ketones bearing a chloro group at the 2 position (of a pyridyl or phenyl group) thus synthesized were next converted through palladium-catalyzed ring closure to polycycles of the 5H-indeno[1,2-b]pyridin-5-one, 11H-indeno[1,2-b]quinolin-11-one, 9H-indeno[2,1-c]pyridin-9-one, and 8H-indeno[2,1-b]thiophen-8-one families.

Full text of DOI:10.1016/j.tetlet.2013.04.020

Tetrahedron Letters 54 (2013) 3154–3157
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Efficient two-step access to azafluorenones and related compounds
Nada Marquise a, Philip J. Harford b, Floris Chevallier a, Thierry Roisnel c, Andrew E. H. Wheatley b,
,
⇑
Philippe C. Gros d, Florence Mongin a,
⇑
a Chimie et Photonique Moléculaires, UMR 6226 Institut des Sciences Chimiques de Rennes, CNRS-Université de Rennes 1, Bâtiment 10A, Case 1003, Campus Scientifique de
Beaulieu, 35042 Rennes, France
b Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
c Centre de Diffractométrie X, UMR 6226 Institut des Sciences Chimiques de Rennes, CNRS-Université de Rennes 1, Bâtiment 10B, Campus Scientifique de Beaulieu, 35042
Rennes, France
d HECRIN, SRSMC, Université de Lorraine-CNRS, Boulevard des Aiguillettes, 54506 Vandœuvre-Lès-Nancy, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 February 2013
Revised 2 April 2013
Accepted 5 April 2013
Available online 12 April 2013
Crystals of a lithiocuprate prepared from copper(I) chloride and lithium 2,2,6,6-tetramethylpiperidide
(2 equiv) were isolated and analyzed by X-ray diffraction as (TMP)2Cu(Cl)Li2ꢀTHF. The observation of this
species is consistent with its having a role in deprotocupration–aroylation. Phenyl pyridyl ketones, phe-
nyl quinolyl ketones, and phenyl thienyl ketones were prepared in tetrahydrofuran using the lithiocup-
rate and aroyl chorides as electrophiles. Diaryl ketones bearing a chloro group at the 2 position (of a
pyridyl or phenyl group) thus synthesized were next converted through palladium-catalyzed ring closure
to polycycles of the 5H-indeno[1,2-b]pyridin-5-one, 11H-indeno[1,2-b]quinolin-11-one, 9H-indeno[2,1-
c]pyridin-9-one, and 8H-indeno[2,1-b]thiophen-8-one families.
Keywords:
Deprotometallation
Copper
Ó 2013 Elsevier Ltd. All rights reserved.
Lithium
Heterocycle
Palladium
Introduction
fluorenone synthesis using 2-bromo diaryl ketone reagents,7 which
are more expensive than the corresponding chloro analogues.
Azafluorenones represent the heterocyclic cores of many mole-
cules of biological interest; derivatives have, for example, been de-
scribed for their antifungal,1 antibacterial,2 and antimalarial3
properties.
Results and discussion
Recently, in order to gain more information about the lithiocup-
rate base, we attempted its crystallization. In the present case, the
treatment of LiTMP with CuCl in toluene/THF followed by concen-
tration and recrystallization from toluene at ꢁ27 °C afforded color-
less crystals which X-ray diffraction showed to be
(TMP)2Cu(Cl)Li2ꢀTHF 1 (Fig. 1).8 A dimer is revealed in the solid
state based on a (LiCl)2 core with the halide ions remote from cop-
per. The structure is closely related to the dimers of (TMP)2Cu(CN)-
Li2ꢀTHF9 and (TMP)2Cu(I)Li2ꢀTHF,10 with Cu maintaining a near
linear geometry (N(1)–Cu(1)–N(2) 174.45(11)°), and the amides
acting as inter-metal bridges (Cu(1)–N(1)–Li(1) 92.1(2), Cu(1)–
N(2)–Li(2) 84.77(19)°). However, in contrast to the cyanide- and
iodide-based dimers, in which the THF-solvated Li+ ions reside
within 0.14 and 0.15 Å, respectively, of planes defined by the
(LiX)2 (X = N, I) metallocyclic cores of the structures, in 12 they
are significantly displaced (by 0.49 Å) from the analogous (LiCl)2
core plane. Lastly, we can empirically view formation of the high-
er-order dimer as resulting from the formal insertion of two units
of in situ-generated LiClꢀTHF11 into a lower-order dimer based on a
(NCuNLi)2 ring.10
In the course of the development of lithium-metal amido-based
heterometallic bases, synergic reagents with which to functional-
ize aromatic compounds unsuitable for reaction with traditional
organolithium bases have been identified and developed.4
Amongst these, the cuprate base prepared in situ from CuCl and
2 equiv of LiTMP (TMP = 2,2,6,6-tetramethylpiperidino), in addi-
tion to achieving regioselective deprotonation, gave metallated
derivatives capable of reacting in situ with aroyl chlorides to afford
the corresponding ketones.5 We realized that this approach, ap-
plied to the synthesis of 2-chloro diaryl ketones, could be com-
bined with transition metal-catalyzed cyclization to afford a
straightforward method by which to synthesize azafluorenones
and related compounds. In addition, whereas coupling involving
C–H bond activation has been the subject of numerous investiga-
tions,6 to our knowledge only one study has been devoted to aza-
⇑
Corresponding authors. Tel.: +33 2 2323 6931; fax: +33 2 2323 6955.
E-mail addresses: aehw2@cam.ac.uk (A.E.H. Wheatley), florence.mongin@
univ-rennes1.fr (F. Mongi.
0040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2013.04.020

N. Marquise et al. / Tetrahedron Letters 54 (2013) 3154–3157
3155
Figure 1. ORTEP diagram (50% probability) of the dimer of lithiocuprate 1 with H-atoms omitted.13
Whereas early synthetic work with these systems presumed the
use of higher-order cuprates such as (TMP)2Cu(CN)Li2 as deproto-
cuprating agents,9 this cuprate structure-type has been established
to be in competition10,11 with lower-order (TMP)2CuLi and both
higher- and lower-order lithiocuprates have proved capable of
being isolated from similar media.10 Moreover, the conditions em-
ployed here – 2:1 combination of lithium amide with CuCl in THF/
TMEDA – favor retention in solution of in situ-formed LiCl.12 Com-
bined with recent synthetic results concerning the metallation of
halopyridines5c and the theoretical modeling of cuprate bases,10
these data suggest that efficient deprotocupration–aroylation re-
quires only the presence of components consistent with the formu-
lation of a higher-order bis(amido)cuprate. Indeed, spectroscopic
studies on 1 show the presence in both benzene and THF solutions
of the higher-order cuprate alongside a small but detectable
amount of another species.8 Based on recent studies that reported
the characterization of TMP2CuLi it is possible to attribute the min-
or signals to the in situ formation of this lower-order cuprate.10
Table 1
Synthesis of 2, 3a–c, 4, 5, and 6 by deprotocupration followed by aroylation (TMEDA = N,N,N0,N0-tetramethylethylenediamine)
1) (TMP)2CuLi·LiCl (1 equiv)
O
TMEDA (1 equiv)
Ar
H
Ar
THF, rt, 2 h
2) ClC(O)Ar'
Ar'
Entry
1
Ar–H
ClC(O)Ar0
Product
Yield (%)
44a,5
O
H
COPh
Cl
2
Cl
Cl
Ph
N
H
Cl
N
O
2
3
4
R0 = H
3a
3b
3c
90a,5
80a
O
O
R0 = 4-OMe
R0 = 2-Cl
R'
2
2
R'
59a
N
Cl
4
4
N
N
Cl
O
H
Cl
Cl
5
4
56a
Cl
N
S
OMe
OMe
Cl
Cl
6
7
5
6
57b (35)a
Cl
Cl
H
S
O
O
O
Cl
Ph
Cl
H
85b
S
S
COPh
a
Trapping step performed at rt.
Trapping step performed at 60 °C.
b

3156
N. Marquise et al. / Tetrahedron Letters 54 (2013) 3154–3157
Our deprotocupration–aroylation method was applied to the
synthesis of 3-benzoyl-2-chloroquinoline and -2-chloropyridine 2
and 3a (44% and 90% yield, respectively),5 compounds for which
subsequent cyclization could lead to heterocyclic tricycles (Table 1,
cat. Pd(OAc)2
Cl
cat. Cy3P·HBF4
O
entries 1, 2). We also chose the diaryl ketones 3b–c,14 4,15 16, and
5
O
K2CO3 (2 equiv)
Pr4NCl (2 equiv)
DMF, 130 °C, 16 h
48% yield
617 as other potential candidates to evaluate the combination of
deprotocupration–aroylation with transition metal-catalyzed
cyclization, and prepared them by extending the method (Table 1,
entries 3–7). In particular, we discovered that the trapping step
usually performed at room temperature can be improved in the
thiophene series by raising the temperature to 60 °C (Table 1, en-
tries 6, 7).
We next turned to the synthesis of azafluorenones and related
compounds. Owing to their presence in natural products and com-
pounds of medicinal interest, the synthesis of fluorenones has re-
ceived significant attention.18 With the aim of developing a short
access method to such compounds, here we have targeted a route
involving cyclization of the ketones 2–6.
N
OMe
OMe
N
4
10
Ph
cat. Pd(OAc)2
O
cat. tBu3P·HBF4
O
4
+
N
O
K2CO3 (2 equiv)
DMF, 130 °C, 24 h
N
OMe
11: 14% yield
12: 12% yield
Scheme 3. Synthesis and ORTEP diagram (50% probability) of 1-methoxy-9H-
indeno[2,1-c]pyridin-9-one (10).
4-Azafluorenone (7) was previously synthesized by several
groups,19 and sometimes under harsh conditions. For example,
Stauffer and co-workers prepared the tricycle by heating 2-phen-
ylnicotinic acid at 190 °C in polyphosphoric acid, 2-phenylnicotinic
acid being prepared in two steps from 2-chloro-3-cyanopyridine.20
The cyclization of 2-chloro-3-benzoylpyridine (3a) to 4-azafluore-
none (7)21 was first optimized. Inspired by a previously described
cyclization of 2-chloro diaryl aniline to carbazole,22 the reactions
were attempted in the presence of catalytic amounts of Pd(OAc)2
and electron-rich bulky trialkyl phosphine, and used K2CO3 as a
base. Using Cy3P in DMF at 130 °C, different transition metal–
ligand ratios were tested. The best result was observed using
5 mol% of Pd(OAc)2 and 10 mol% of phosphine; using 20 mol% of
Pd(OAc)2, and 10 mol% of phosphine, a lower yield was observed
due to recovered starting material (Scheme 1).
O
O
S
S
S
Cl
13
cat. Pd(OAc)2
cat. L·HBF4
5
6
or
O
K2CO3 (2 equiv)
DMF, 130 °C, 16 h
L = Cy3P:
90% yield from 5
35% yield from 6
Cl
L = tBu3P:
38% yield from 5
17% yield from 6
Scheme 4. Synthesis and ORTEP diagram (50% probability) of 8H-indeno[2,1-
b]thiophen-8-one (13).
Under the best reaction conditions identified in Scheme 1,23
11H-indeno[1,2-b]quinolin-11-one (8)24 and 8-methoxy-5H-inde-
no[1,2-b]pyridin-5-one (9)25 were formed from the ketones 2 and
3b respectively, and isolated in 63–69% yield (Scheme 2). The ke-
tone 3c, expected to allow further coupling thanks to an additional
chloro group, did not afford the expected chloro cyclized product;
bare 5H-indeno[1,2-b]pyridin-5-one (7) was the sole product iden-
O
O
Pd(OAc)2 (x mol.%)
Cy3P·HBF4 (y mol.%)
t
tified using Cy3P or Bu3P.
Starting from the diaryl ketone 4, in which the 2-chloro group is
connected to the phenyl component, the cyclization proved more
difficult. Recourse to a tetraalkylammonium chloride, as recom-
mended by Kraus and Kempema for the cyclization of bromo diaryl
ketones,7 led to the expected methoxy-substituted 9H-indeno[2,1-
K2CO3 (2 equiv)
Cl
3a
N
DMF, 130 °C, 48 h
N
7
x = 5; y = 10: 87% yield
x = 5; y = 15: 82% yield
x = 10; y = 10: 81% yield
x = 20; y = 10: 64% yield
t
c]pyridin-9-one 1026 in 48% yield. Using Bu3P in this case did not
give the same result and led to the cyclized demethylated aza-xan-
thone 1127 and the non-cyclized dechlorinated product 12,5b both
of which were isolated in low yields (Scheme 3).
Scheme 1. Optimization of the Pd(OAc)2–Cy3P ratio for the cyclization affording
5H-indeno[1,2-b]pyridin-5-one (or 4-azafluorenone, 7).
8H-Indeno[2,1-b]thiophen-8-one (13) was efficiently synthe-
sized by Campo and Larock from 3-(2-bromophenyl)thiophene
using palladium-catalyzed cyclocarbonylation.28 Starting from 5,
which bears the chloro group on the phenyl ring, both Cy3P and
tBu3P were tested as ligand in DMF at 130 °C, affording 1329 in
90% and 38% yield, respectively. Lower 35% and 17% yields were
respectively obtained from 6, for which the chloro group is present
on the thiophene ring (Scheme 4).
O
O
cat. Pd(OAc)2
cat. Cy3P·HBF4
K2CO3 (2 equiv)
DMF, 130 °C, 24 h
N
O
Cl
2
N
8
63% yield
O
cat. Pd(OAc)2
Conclusion
cat. Cy3P·HBF4
K2CO3 (2 equiv)
In summary, different heterocyclic diaryl ketones were synthe-
sized by deprotocupration–aroylation using a lithiocuprate which
crystallized as (TMP)2Cu(Cl)Li2ꢀTHF. Concerning the diaryl ketones
bearing a halogen at the 2 position of one of the aryl groups, their
cyclization under palladium catalysis was considered. Cy3P was
Cl
3b
OMe
N
DMF, 130 °C, 24 h
N
OMe
9
69% yield
Scheme 2. Cyclization of 2 and 3b giving 11H-indeno[1,2-b]quinolin-11-one (8)
and 8-methoxy-5H-indeno[1,2-b]pyridin-5-one (9).

N. Marquise et al. / Tetrahedron Letters 54 (2013) 3154–3157
3157
t
11. Haywood, J.; Morey, J. V.; Wheatley, A. E. H.; Liu, C.-Y.; Yasuike, S.; Kurita, J.;
Uchiyama, M.; Raithby, P. R. Organometallics 2009, 28, 38–41.
12. Davies, R. P. Coord. Chem. Rev. 2011, 255, 1226–1251.
13. Selected bond lengths (Å) and angles (°): Li1–Cl1 2.344(6), Li1–Cl1A 2.328(6),
Li1–N1 1.966(6), Li2–Cl1 2.371(6), Li2–N2 2.016(6), Cu1–N1 1.908(2), Cu1–N2
1.918(2), Cl1A–Li1–Cl1 98.7(2), Li1–Cl1–Li1A 81.3(2), Cl1–Li1–N1 128.5(3),
Cl1–Li2–N2 128.2(3), N1–Cu1–N2 174.45(11).
identified as a more suitable ligand than Bu3P for performing the
reactions. Except when a second halogen was present on the 2-
chloro diaryl ketone, azafluorenones and related compounds
(including quinolyl or thienyl moieties instead of pyridyl) were iso-
lated in medium to high yields.
14. The 1H and 13C NMR data of 3b are analogous to those described: (a)
Kobayashi, K.; Suzuki, T.; Horiuchi, M.; Shiroyama, Y.; Konishi, H. Synthesis
2011, 2897–2906; (b) Compound 3c: orange oil; 1H NMR (300 MHz, CDCl3) d
7.43 (m, 4H), 7.57 (dd, 1H, J = 7.6 and 1.7 Hz), 7.88 (dd, 1H, J = 7.6 and 2.0 Hz),
8.52 ppm (dd, 1H, J = 4.8 and 2.0 Hz); 13C NMR (75 MHz, CDCl3) d 122.7 (CH),
127.3 (CH), 130.9 (CH), 131.2 (CH), 132.8 (C), 133.3 (CH), 134.9 (C), 137.1 (C),
139.5 (CH), 148.6 (C), 151.8 (CH), 193.1 ppm (C@O); HRMS (ESI): m/z calcd for
Acknowledgments
The authors gratefully acknowledge the financial support of the
Agence Nationale de la Recherche (ACTIVATE program) (to N.M.
and P.H.), the Institut Universitaire de France (to F.M.), Rennes
Métropole (to F.M.) and the UK EPSRC (to P.H.).
C
12H735Cl2NNaO [(M+Na)+Å] 273.9802, found 273.9805.
15. Compound 4: yellow powder; mp 65 °C; 1H NMR (300 MHz, CDCl3) d 3.81 (s,
3H), 7.01 (dd, 1H, J = 7.5 and 4.9 Hz), 7.37 (m, 3H), 7.46 (m, 1H), 7.99 (dd, 1H,
J = 7.5 and 2.0 Hz), 8.34 ppm (dd, 1H, J = 4.9 and 2.0 Hz); 13C NMR (75 MHz,
CDCl3) d 53.9 (CH3), 117.1 (CH), 121.8 (C), 126.9 (CH), 129.7 (CH), 129.9 (CH),
131.5 (CH), 131.6 (C), 139.7 (C), 140.6 (CH), 151.3 (CH), 162.2 (C), 193.7 ppm
Supplementary data
(C@O); HRMS (ESI): m/z calcd for
13H1035ClNNaO2 [(M+Na)+Å
248.0478 and 270.0298, found 248.0483 and
270.0298, respectively.
C
13H1135ClNO2 [(M+H)+Å
]
and
Supplementary data (X-ray diffraction analysis and CIF files of 1
(CCDC 884940), 10 (CCDC 885440), and 13 (CCDC 885439), and
NMR spectra of 3c, 4, 6, 9, 10 and 13) associated with this article
can be found, in the online version, at http://dx.doi.org/10.1016/
j.tetlet.2013.04.020.
C
]
16. The 1H and 13C NMR data of 5 are analogous to those described: Cahiez, G.;
Luart, D.; Lecomte, F. Org. Lett. 2004, 6, 4395–4398.
17. Compound 6: yellow viscous oil; 1H NMR (300 MHz, CDCl3) d 6.99 (d, 1H,
J = 5.2 Hz), 7.41 (m, 2H), 7.51 (m, 2H), 7.77 ppm (m, 2H); 13C NMR (75 MHz,
CDCl3) d 128.4 (2CH), 129.6 (2CH), 130.1 (CH), 130.7 (CH), 133.0 (CH), 134.3
(C), 137.8 (C), 187.8 ppm (C@O), one C not seen; HRMS (ESI): m/z calcd for
References and notes
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11H835ClOS [(M+H)+Å] and C11H735ClNaOS [(M+Na)+Å] 222.9984 and 244.9804,
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8. Compound 1: mp 173–175 °C; elemental analysis calcd (%) for
(11 mg, 50
lmol), Cy3PꢀHBF4 (37 mg, 0.1 mmol), the required ketone
(1.0 mmol), and in some cases Pr4NCl (0.44 g, 2 mmol), in DMF (4 mL) was
heated at 130 °C for 16 to 48 h. After filtration over a celite pad, washing using
CH2Cl2 (3 ꢂ 10 mL), and removal of the solvent under reduced pressure, the
product was isolated after purification by flash chromatography on silica gel.
24. The 1H NMR data of 8 are analogous to those described: Prostakov, N. S.;
Pleshakov, V. G.; Zain-ul-Abedin, M.; Kordova, I. R.; Zakharov, V. F.; Zvolinskii,
V. P. Zh. Org. Khim. 1982, 18, 640–652.
C
44H88Cu2Li4N4O2Cl2: C 56.77, H 9.53, N 6.02, Cl 7.62; found: C 56.34, H 9.69,
N 6.03, Cl 7.92; 1H NMR (500 MHz, 298 K, C6D6): d 3.71 (br, m, 4H; THF), 2.09
(br, m, 2H; TMP-3,5), 1.84 (s, 6H; TMP-Me), 1.71–1.68 (m, 18H; TMP-Me), 1.50
(br, m, 6H; TMP-3,5), 1.43 (br, m, 4H; THF), 1.18 ppm (m, 4H; TMP-4); 13C NMR
(125 MHz, 298 K, C6D6, G = lower-order or Gilman-type cuprate TMP2CuLi,
L = higher-order or Lipshutz-type cuprate 1): d 68.7 (THF), 54.6 (TMP-2, G), 54.0
(TMP-2, L), 52.1 (TMP-2, L), 42.6 (TMP-3,5 G), 42.4 (TMP-3,5 L), 41.1 (TMP-3,5
L), 40.6 (TMP-Me, G), 39.0 (TMP-Me L), 38.6 (TMP-Me, L), 35.0 (TMP-Me, G),
34.6 (TMP-Me, L), 32.0 (TMP-Me, L), 25.3 (THF), 20.6 (TMP-4, L), 19.8 (TMP-4,
L), 19.7 ppm (TMP-4, G); 7Li NMR spectroscopy (194 MHz, 298 K, C6D6,
G = TMP2CuLi, L = 1): d 1.9 (s, 6Li, L), 1.3 ppm (s, Li, G); 1H NMR (500 MHz,
298 K, d8-THF): 3.65 (br, m, 4H; THF), 1.81 (br, m, 4H; THF), 1.68 (br, m, 4H;
TMP-4), 1.38, 1.09 (s, 24H, TMP-Me), 1.33 ppm (br, m, 8H, TMP-3,5); 1H NMR
(500 MHz, 273 K, d8-THF): d 3.65 (br, m, 4H; THF), 1.81 (br, m, 4H; THF), 1.67
(br, m, 4H; TMP-4), 1.34, 1.08 (s, 24H, TMP-Me), 1.31 ppm (br, m, 8H, TMP-3,5);
13C NMR (125 MHz, 298 K, d8-THF, G = TMP2CuLi, L = 1): d 68.2 (THF), 54.2
(TMP-2 L), 50.0 (TMP-2 G), 41.9 (TMP-3,5 L), 38.6 (TMP-3,5 G), 37.3 (br, m,
TMP-Me, L), 32.2, 32.1 (TMP-Me G), 26.4 (THF), 20.5 (TMP-4 L), 19.3 ppm (TMP-
4, G); 13C NMR (125 MHz, 273 K, d8-THF, G = TMP2CuLi, L = 1): d 65.1 (THF),
51.3 (TMP-2 L), 47.1 (TMP-2 G), 39.1 (TMP-3,5 L), 35.7 (TMP-3,5 G), 34.8 (br, m,
TMP-Me, L), 29.4, 29.3 (TMP-Me G), 23.0 (THF), 18.0 (TMP-4 L), 17.5 ppm (TMP-
4, G); 7Li NMR spectroscopy (194 MHz, 298 K, d8-THF): d 0.7 ppm (s); 7Li NMR
spectroscopy (194 MHz, 273 K, d8-THF): d 0.2 ppm (s).
25. Compound 9: yellow powder; mp 113 °C; 1H NMR (300 MHz, CDCl3) d 3.96 (s,
3H), 6.92 (dd, 1H, J = 8.3 and 2.3 Hz), 7.24 (dd, 1H, J = 7.4 and 5.1 Hz), 7.41 (d,
1H, J = 2.3 Hz), 7.7 (d, 1H, J = 8.3 Hz), 7.89 (dd, 1H, J = 7.4 and 1.6 Hz), 8.62 ppm
(dd, 1H, J = 5.1 and 1.6 Hz); 13C NMR (75 MHz, CDCl3) d 56.1 (CH3), 106.4 (CH),
116.7 (CH), 123.7 (CH), 126.4 (CH), 127.8 (C), 129.8 (C), 131.2 (CH), 146.5 (C),
153.4 (CH), 164.2 (C), 166.1 (C), 190.3 ppm (C@O); HRMS (ESI): m/z calcd for
C
13H9NNaO2 [(M+Na)+Å] 234.0531, found 234.0534.
26. Compound 10: yellow powder; mp 160 °C; 1H NMR (300 MHz, CDCl3) d 4.13 (s,
3H), 7.15 (d, 1H, J = 5.0 Hz), 7.44 (td, 1H, J = 7.2 and 1.6 Hz), 7.49–7.60 (m, 2H),
7.71 (ddd, 1H, J = 7.2, 1.1 and 0.8 Hz), 8.37 (d, 1H, J = 5.0 Hz); 13C NMR (75 MHz,
CDCl3) d 54.4 (CH3), 109.8 (CH), 113.4 (C), 121.5 (CH), 124.3 (CH), 131.5 (CH),
134.1 (C), 134.2 (CH), 141.1 (C), 155.0 (CH), 156.4 (C), 161.0 (C), 191.5 (C@O);
HRMS (ESI): m/z calcd for C13H9NNaO2 [(M+Na)+Å] 234.0531, found 234.0532.
27. The 1H and 13C NMR data of 11 are analogous to those described: Dubrovskiy,
A. V.; Larock, R. C. Org. Lett. 2010, 12, 3117–3119.
28. Campo, M. A.; Larock, R. C. J. Org. Chem. 2002, 67, 5616–5620.
29. Mp 106 °C (Arcus, C. L.; Barrett, G. C. J. Chem. Soc. 1960, 5, 2098–2102: mp 107–
109 °C).
9. Usui, S.; Hashimoto, Y.; Morey, J. V.; Wheatley, A. E. H.; Uchiyama, M. J. Am.
Chem. Soc. 2007, 129, 15102–15103.
10. Komagawa, S.; Usui, S.; Haywood, J.; Harford, P. J.; Wheatley, A. E. H.;
Matsumoto, Y.; Hirano, K.; Takita, R.; Uchiyama, M. Angew. Chem., Int. Ed. 2012,
51, 12081–12085.