N-heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C-H bond benzylation of (benzo)oxazoles with benzyl chlorides

Article abstract of DOI:10.1016/j.tet.2015.07.030

The first example of phosphine-free, NHC-Pd(II) complex catalyzed direct C-H bond benzylation of (benzo)oxazoles with benzyl chlorides was reported in this paper. Under the suitable conditions, all reactions worked well enough to give the desired C2-benzylated products in good to almost quantitative yields, providing a facile and straight pathway for the C-H bond benzylation of (benzo)oxazoles within short time.

Full text of DOI:10.1016/j.tet.2015.07.030

Tetrahedron xxx (2015) 1e6
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Tetrahedron
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N-heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed
CeH bond benzylation of (benzo)oxazoles with benzyl chlorides
*
Ya-Yun Ji, Yu Zhang, Yuan-Yuan Hu, Li-Xiong Shao
College of Chemistry and Materials Engineering, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang Province 325035,
People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
The first example of phosphine-free, NHCePd(II) complex catalyzed direct CeH bond benzylation of
(benzo)oxazoles with benzyl chlorides was reported in this paper. Under the suitable conditions, all
reactions worked well enough to give the desired C2-benzylated products in good to almost quantitative
yields, providing a facile and straight pathway for the CeH bond benzylation of (benzo)oxazoles within
short time.
Received 27 May 2015
Received in revised form 7 July 2015
Accepted 10 July 2015
Available online xxx
Ó 2015 Elsevier Ltd. All rights reserved.
Keywords:
N-heterocyclic carbene-palladium complex
(Benzo)oxazole
CeH bond functionalization
Benzylation
Synthetic method
1. Introduction
CeH bond benzylation of (benzo)oxazoles with benzyl chlorides.7
Herein, we report these results in detail.
During the recent years, the transition metal catalyzed direct
CeH bond functionalization has become a versatile methodology
for the modification of heteroaromatic compounds.1 Recently,
2. Results and discussion
a
well-defined
N-heterocyclic
carbene-palladium(II)-1-
methylimidazole [NHCePd(II)-Im] complex 1 was developed by
our group and proven to be a highly efficient catalyst in CeC and
CeN coupling reactions.2,3 In addition, recent studies have shown
that this complex was also a good catalyst in the direct CeH bond
arylation of heteroaromatic compounds such as (benzo)oxazoles
and (benz)imidazoles, and fluorenes with aryl chlorides.4 These
successful experiences thus prompted us to further test the cata-
lytic activity of NHCePd(II)-Im complex 1 in organic synthesis. In
this case, it was found that 2-substituted (benzo)oxazoles are in-
teresting backbones because of their special biological and physical
properties, or being important precursors in organic synthesis.5
Therefore, based on our results on the NHCePd(II)-Im complex 1
catalyzed direct CeH bond arylation of (benzo)oxazoles with aryl
chlorides,4a we then turned our interest to its application toward
direct CeH bond benzylation of (benzo)oxazoles with benzyl
chlorides.6 In addition, to the best of our knowledge, this is the first
example of phosphine-free, NHCePd(II) complex catalyzed direct
Initially, the reactions between benzoxazole 2a (0.6 mmol) and
benzyl chloride 3a (0.5 mmol) as the model substrates in the
presence of NHCePd(II)-Im ꢀcomplex 1 (1.0 mol %) using toluene as
the solvent (2.0 mL) at 130 C for 3 h were carried out to evaluate
various bases (Table 1, entries 1e6). Among the bases screened,
LiOtBu gave the best yield (Table 1, entry 3). However, almost no
reaction occurred when some other bases such as KOtBu, NaOtBu,
KOH, Li2CO3 and NaHCO3 were used, respectively (Table 1, entries 1,
2 and 4e6). Subsequently, some solvents were also tested using
LiOtBu as the base. For example, when dioxane was used as the
solvent, product 4a was obtained in 68% yield (Table 1, entry 7).
Using other solvents such as THF, CH3CN and DMSO, almost no
desired product was detected (Table 1, entries 8e10). Finally, when
the catalyst loading was elevated to 2.0 mol %, the yield could be
increased to 98% within 3 h (Table 1, entry 11). Further study
showed that 130 ꢀC was necessary to give satisfactory result within
3 h. For example, the yield was decꢀreased to 82% when the reaction
temperature was lowered to 120 C, even with increased catalyst
loading (2.0 mol %) (Table 1, entry 12). In addition, it was confirmed
that in the absence of NHCePd(II)-Im complex 1, no reaction
occurred.
* Corresponding author. Tel./fax: þ86 577 86689300; e-mail address: Shaolix@
wzu.edu.cn (L.-X. Shao).
http://dx.doi.org/10.1016/j.tet.2015.07.030
0040-4020/Ó 2015 Elsevier Ltd. All rights reserved.
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Y.-Y. Ji et al. / Tetrahedron xxx (2015) 1e6
Table 1
increasing the catalyst loading to 3.0 mol % under similar conditions
(Table 2, entry 3). However, its analogue, 3-methoxybenzyl chloride
3b was the most suitable substrate in such transformation to give
the highest yield (Table 2, entry1). Sterically-hindered substituent
slightly affected the reaction. For instance, for the reaction in-
volving 2-methylbenzyl chloride 3d, product 4d was observed in
88% yield (Table 2, entry 4), while for its analogue, 3- and 4-
methylbenzyl chlorides 3e and 3f, higher yields were obtained
(Table 2, entries 5 and 6). 4-Fluorobenzyl chloride 3h was superior
substrate than 3-fluorobenzyl chloride 3g, giving higher yield un-
der identical conditions (Table 2, entries 7 and 8).
Optimization for the NHCePd(II)-lm complex 1 catalyzed reaction of benzoxazole 2a
with benzyl chloride 3a
Subsequently, the limitation and generality of this reaction was
further tested using a variety of benzoxazoles 2 and benzyl chlo-
rides 3 as the substrates under the optimal conditions. The results
are summarized in Table 3. All reactions took place well to give the
desired C2-benzylated products 4 in good to almost quantitative
yields. Substituents on the benzoxazoles 2 have apparent effect on
the reactions. For example, for the reactions involving 5-
methylbenzoxazole 2b and 6-methylbenzoxazole 2e, 3.0 mol %
catalyst loading was necessary to achieve satisfactory yields within
3 h, while 1.0 mol % catalyst loading was efficient enough for the
reactions involving 5-tert-butylbenzoxazole 2c (Table 3, entries
1e10 and 15e18). On the other hand, it seems that substituents on
the benzyl chlorides 3 did not affect the reactions significantly. For
instance, electron-donating, -neutral and -withdrawing groups on
the phenyl rings of benzyl chlorides are all tolerated to give the
corresponding products 4 in good to almost quantitative yields.
Entrya
Solvent
Base
Yield (%)b
1
2
3
4
5
6
7
8
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Dioxane
THF
CH3CN
DMSO
Toluene
Toluene
KOtBu
NaOtBu
LiOtBu
KOH
Li2CO3
NaHCO3
LiOtBu
LiOtBu
LiOtBu
LiOtBu
LiOtBu
LiOtBu
nr
nr
88
nr
<5
nr
68
<5
nr
nr
98
82
9
10
11c
12d
a
Otherwise specified, all reactions were carried out using 2a (0.6 mmol), 3a
(0.5 mmol), 1 (1.0 mol %), base (2.0 equiv) in solvent (2.0 mL) at 130 ꢀC for 3 h.
Table 3
NHCePd(II)-lm complex 1 catalyzed reactions of benzoxazoles 2 with benzyl chlo-
rides 3
b
Isolated yields.
1 (2.0 mol %).
1 (2.0 mol %), 120 ꢀC.
c
d
With the optimal conditions established, the reactions between
benzoxazole 2a and a variety of benzyl chlorides 3 were first in-
vestigated to show the generality (Table 2). All reactions worked
well under suitable conditions. Substituents on the benzyl chlo-
rides affected the reactions to some extent. For example, benzyl
chlorides having electron-donating methoxy group such as 4-
methoxybenzyl chloride 3c was not a suitable substrate under
the optimal conditions, giving the lowest yield (Table 2, entry 2). To
our pleasure, very high yield can also be achieved by simply
Entrya
2 (R)
3 (R0)
[X]
Yield (%)b
1
2
3
4
5
6
7
8
2b (5-Me)
2b
2b
2b
3a (H)
3b (3-OMe)
3d (3-Me)
3f (4-Me)
3g (3-F)
3h (4-F)
3a
3.0
3.0
3.0
3.0
3.0
3.0
1.0
1.0
1.0
1.0
2.0
2.0
2.0
2.0
3.0
3.0
3.0
4j, 90
4k, 87
4l, 83
4m, 81
4n, 83
4o, 87
4p, 94
4q, 97
4r, 93
4s, 98
4t, 90
4u, 80
4v, 89
4w, 86
4x, 85
4y, 86
4z, 86
2b
2b
2c (5-tBu)
2c
2c
2c
2d (5-F)
2d
2d
2d
2e (6-Me)
3c (4-OMe)
3f
9
Table 2
10
11
12
13
14
15
16
17
3h
3a
3c
3f
3h
3a
3c
3f
NHCePd(II)-lm complex
chlorides 3
1 catalyzed reactions of benzoxazole 2a with benzyl
2e
2e
a
All reactions were carried out using 2 (0.6 mmol), 3 (0.5 mmol), 1 (X mol %),
LiOtBu (2.0 equiv) in toluene (2.0 mL) at 130 ꢀC for 3 h.
Entrya
3 (R0)
Yield (%)b
b
Isolated yields.
1
2
3c
4
5
6
7
8
9
3b (3-OMe)
3c (4-OMe)
3c (4-OMe)
3d (2-Me)
3e (3-Me)
3f (4-Me)
3g (3-F)
4b, 98
4c, 38
4c, 97
4d, 88
4e, 95
4f, 92
4g, 86
4h, 96
4i, 86
Finally, the reactions between various 5-aryloxazoles 2 and
benzyl chlorides 3 were also investigated under the optimal con-
ditions. The results are shown in Table 4. All reactions also took
place smoothly to give the desired C2-benzylated products 4 in
good to excellent yields. It seems that electron-rich, -neutral and
-poor groups on the phenyl rings of both substrates 2 and 3 had no
effect on the reactions. For example, Electron-donating groups such
as methoxy (3c) and methyl (3f) groups, electron-withdrawing
group such as fluorine atom (3h) on the phenyl rings of benzyl
3h (4-F)
3i (4-tBu)
a
Otherwise specified, all reactions were carried out using 2a (0.6 mmol), 3
(0.5 mmol), 1 (2.0 mol %), LiOtBu (2.0 equiv) in toluene (2.0 mL) at 130 ꢀC for 3 h.
b
Isolated yields.
1 (3.0 mol %).
c
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Y.-Y. Ji et al. / Tetrahedron xxx (2015) 1e6
3
4.2.1. Compound 4a7c yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
Table 4
NHCePd(II)-lm complex 1 catalyzed reactions of aryloxazoles 2 with benzyl chlo-
rides 3
d
7.70e7.66 (m,1H), 7.45e7.41 (m, 1H), 7.36 (d, J¼7.0 Hz, 2H), 7.32 (t,
J¼7.5 Hz, 2H), 7.28e7.23 (m, 3H), 4.25 (s, 2H). 13C NMR (125 MHz,
CDCl3)
d 165.2, 151.1, 141.3, 134.8, 129.0, 128.8, 127.3, 124.7, 124.2,
119.8, 110.4, 35.3.
4.2.2. Compound 4b8 yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.69e7.67 (m, 1H), 7.45e7.41 (m, 1H), 7.29e7.22 (m, 3H), 6.95 (d,
J¼7.5 Hz, 1H), 6.92 (s, 1H), 6.80 (dd, J¼8.5, 2.5 Hz, 1H), 4.22 (s, 2H),
3.76 (s, 3H). 13C NMR (125 MHz, CDCl3)
164.9, 159.8, 151.0, 141.3,
Entrya
2 (R)
3 (R0)
Yield (%)b
d
136.1, 129.7, 124.6, 124.1, 121.2, 119.7, 114.7, 112.7, 110.3, 55.1, 35.1.
1
2
3
4
5
6
7
8
2e (H)
2e
2e
2e
2f (4-F)
2f
2f
2g (4-Me)
2g
2g
2h (2-Me)
2h
2h
3a (H)
3c (4-OMe)
3f (4-Me)
3h (4-F)
3a
3c
3f
3a
3c
3f
3a
3c
3f
4aa, 83
4ab, 83
4ac, 84
4ad, 94
4ae, 87
4af, 85
4ag, 87
4ah, 83
4ai, 82
4aj, 83
4ak, 87
4al, 84
4am, 93
4.2.3. Compound 4c7d yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS)
d 7.69e7.65 (m, 1H), 7.45e7.41 (m, 1H), 7.29e7.24 (m, 4H),
6.87 (d, J¼8.5 Hz, 2H), 4.19 (s, 2H), 3.76 (s, 3H). 13C NMR (125 MHz,
CDCl3)
d 165.6, 158.8, 150.8, 140.7, 130.0, 126.5, 124.7, 124.2, 119.6,
114.2, 110.4, 55.2, 34.2.
9
10
11
12
13
4.2.4. Compound 4d7d yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS)
7.17e7.14 (m, 3H), 4.23 (s, 2H), 2.38 (s, 3H). 13C NMR (125 MHz,
CDCl3) 165.0, 150.9, 141.3, 136.7, 133.2, 130.5, 129.9, 127.5, 126.3,
d 7.67e7.66 (m, 1H), 7.42e7.40 (m, 1H), 7.29e7.23 (m, 3H),
d
a
All reactions were carried out using 2 (0.5 mmol), 3 (0.6 mmol), 1 (2.0 mol %),
LiOtBu (2.0 equiv) in toluene (2.0 mL) at 130 ꢀC for 3 h.
124.5, 124.0, 119.7, 110.3, 32.9, 19.5.
b
Isolated yields.
4.2.5. Compound 4e yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.70e7.66 (m, 1H), 7.45e7.41 (m, 1H), 7.28e7.23 (m, 2H), 7.21
(t, J¼7.5 Hz, 1H), 7.17e7.15 (m, 2H), 7.06 (d, J¼7.5 Hz, 1H), 4.21
(s, 2H), 2.31 (s, 3H). 13C NMR (125 MHz, CDCl3)
165.2, 151.0,
chlorides are all tolerated. In addition, sterically-hindered sub-
stituent on the phenyl ring of 2-aryloxazoles 2 did not affect the
reaction significantly. For instance, ortho-substituted 5-(2-
methylphenyl)oxazole 2h was also a suitable substrate in such
transformation to give products 4ake4am in good to high yields
under the optimal conditions (Table 4, entries 11e13).
d
141.3, 138.4, 134.6, 129.6, 128.6, 127.9, 125.9, 124.5, 124.0, 119.7,
110.3, 35.1, 21.2. MS (ESI): 246 [MþNa]þ; HRMS (ESI) calcd
for C15H13NNaO [MþNa]þ: 246.0889; found: 246.0888. IR (neat)
n
3021, 2937, 1610, 1565, 1236, 1141, 997, 837, 795, 746,
692 cmꢁ1
.
3. Conclusion
4.2.6. Compound 4f7d pale yellow liquid. 1H NMR (500 MHz, CDCl3,
In conclusion, the first example of phosphine ligand-free,
NHCePd(II) complex catalyzed direct CeH bond benzylation of
(benzo)oxazoles with benzyl chlorides was reported in this paper.
In the presence of a well-defined NHCePd(II)-Im complex, all re-
actions proceeded well to give the desired C2-benzylated (benzo)
oxazoles in good to almost quantitative yields. Various substituents
such as electron-donating, -neutral, -withdrawing and sterically
hindered ones are tolerated in such transformation, giving a facile
and straight pathway for the functionalization of (benzo)oxazoles.
TMS) d 7.69e7.65 (m,1H), 7.43e7.40 (m, 1H), 7.28e7.23 (m, 4H), 7.13
(d, J¼8.0 Hz, 2H), 4.21 (s, 2H), 2.30 (s, 3H). 13C NMR (125 MHz,
CDCl3)
d 165.4, 151.1, 141.4, 137.0, 131.7, 129.5, 128.9, 124.6, 124.1,
119.8, 110.4, 34.9, 21.1.
4.2.7. Compound 4g yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.70e7.68 (m, 1H), 7.47e7.45 (m, 1H), 7.31e7.27 (m, 3H), 7.14 (d,
J¼7.5 Hz, 1H), 7.09 (d, J¼9.5 Hz, 1H), 6.96 (t, J¼8.5 Hz, 1H), 4.25 (s,
2H). 13C NMR (125 MHz, CDCl3)
d
164.4, 162.9 (d, JCeF¼245.125
Hz), 151.0, 141.2, 137.0 (d, JCeF¼7.5 Hz), 130.2 (d, JCeF¼8.375 Hz),
124.7 (d, JCeF¼20.625 Hz), 124.6, 124.2, 119.9, 116.0 (d,
JCeF¼21.75 Hz), 114.3 (d, JCeF¼20.875 Hz), 110.4, 34.8 (d,
JCeF¼1.5 Hz). MS (ESI): 250 [MþNa]þ; HRMS (ESI) calcd for
4. Experimental section
4.1. General remarks
C
14H10FNNaO [MþNa]þ: 250.0639; found: 250.0635. IR (neat)
n
Melting points are uncorrected. NMR spectra were recorded at
300/500 (for 1H NMR) or 125 MHz (for 13C NMR), respectively. 1H
NMR and 13C NMR spectra recorded in CDCl3 solutions were ref-
erenced to TMS (0.00 ppm) and the residual solvent peak
(77.0 ppm), respectively. J-values are in Hertz. Flash column chro-
matography was performed on silica gel (300e400 mesh).
2976, 2914, 2363, 2329, 1610, 1590, 1570, 1486, 1452, 1236, 1138,
834, 793 cmꢁ1
.
4.2.8. Compound 4h9 yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.69e7.66 (m, 1H), 7.46e7.44 (m, 1H), 7.34 (dd, J¼8.5, 5.0 Hz, 2H),
7.30e7.28 (m, 2H), 7.04e7.00 (m, 2H), 4.23 (s, 2H). 13C NMR
(125 MHz, CDCl3)
d
165.1, 162.1 (d, JCeF¼244.5 Hz), 150.8, 140.5,
4.2. Experimental procedure
130.6 (d, JCeF¼8.0 Hz), 130.1, 125.0 (d, JCeF¼5.25 Hz), 124.5 (d,
JCeF¼5.375 Hz), 119.6 (d, JCeF¼3.125 Hz), 115.7 (d, JCeF¼21.375 Hz),
110.6, 34.3.
Under N2 atmosphere, LiOtBu (1.0 mmol), benzoxazole 2a
(0.6 mmol), NHCePd(II)-Im complex 1 (2.0 mol %), dry toluene
(2.0 mL) and benzyl chloride 3a (0.5 mmol) were successively
added into a sealed tube. The mixture was stirred vigorously at
130 ꢀC for 3 h. After cooling to room temperature, the reaction
mixture was concentrated under reduced pressure and the residue
was purified by flash column chromatography on silica gel to afford
pure product 4a.
4.2.9. Compound 4i brown liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.69e7.66 (m, 1H), 7.44e7.42 (m, 1H), 7.36 (d, J¼8.5 Hz, 2H), 7.31
(d, J¼8.5 Hz, 2H), 7.27e7.25 (m, 2H), 4.23 (s, 2H), 1.29 (s, 9H). 13
C
NMR (125 MHz, CDCl3) d 165.4, 151.0, 150.1, 141.4, 131.7, 128.6, 125.7,
124.6, 124.1, 119.8, 110.4, 34.7, 34.4, 31.3. MS (ESI): 288 [MþNa]þ;
HRMS (ESI) calcd for C18H19NNaO [MþNa]þ: 288.1359; found:
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4
Y.-Y. Ji et al. / Tetrahedron xxx (2015) 1e6
288.1359. IR (neat)
n
2961, 2909, 2861, 1613, 1564, 1514, 1454, 1365,
found: 288.1363. IR (neat)
n 2954, 2908, 2868, 1564, 1477, 1361,
1269, 1242, 1139, 1103, 1020, 1000, 828, 806, 743 cmꢁ1
.
1265, 1119, 962, 881, 859, 809 cmꢁ1
.
4.2.10. Compound 4j7c yellow solid. 1H NMR (500 MHz, CDCl3, TMS)
4.2.17. Compound 4q yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
7.71 (s, 1H), 7.35 (d, J¼8.5 Hz, 1H), 7.32 (d, J¼8.5 Hz, 1H), 7.28 (d,
J¼8.5 Hz, 2H), 6.85 (d, J¼8.5 Hz, 2H), 4.17 (s, 2H), 3.75 (s, 3H), 1.35 (s,
9H). 13C NMR (125 MHz, CDCl3)
165.6, 158.7, 149.0, 147.6, 141.2,
d
7.47 (t, J¼1.0 Hz, 1H), 7.36e7.29 (m, 5H), 7.26e7.22 (m, 1H), 7.06
d
(dd, J¼8.5, 1.0 Hz, 1H), 4.23 (s, 2H), 2.42 (s, 3H). 13C NMR (125 MHz,
CDCl3)
d
165.2, 149.3, 141.6, 134.9, 134.0, 129.0, 128.8, 127.3, 125.7,
d
119.7, 109.8, 35.3, 21.4.
129.9, 126.9, 122.1, 116.2, 114.1, 109.4, 55.1, 34.7, 34.3, 31.7. MS (ESI):
318 [MþNa]þ; HRMS (ESI) calcd for C19H21NNaO2 [MþNa]þ:
4.2.11. Compound 4k yellow liquid. 1H NMR (500 MHz, CDCl3,
318.1465; found: 318.1465. IR (neat) n 2959, 2909, 2357, 2324, 1613,
TMS)
d
7.46 (s, 1H), 7.30 (d, J¼8.0 Hz, 1H), 7.23 (t, J¼8.0 Hz, 1H),
1573, 1511, 1483, 1242, 1174, 1034, 961, 834, 809 cmꢁ1
.
7.06 (d, J¼8.0 Hz, 1H), 6.94 (d, J¼8.0 Hz, 1H), 6.90 (s, 1H), 6.79 (dd,
J¼8.0, 2.5 Hz, 1H), 4.20 (s, 2H), 3.76 (s, 3H), 2.42 (s, 3H). 13C NMR
4.2.18. Compound 4r yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
(125 MHz, CDCl3)
d
165.0, 159.8, 149.2, 141.5, 136.2, 133.8, 129.6,
d
7.70 (s, 1H), 7.35 (d, J¼9.0 Hz, 1H), 7.32 (d, J¼9.0 Hz, 1H), 7.24 (d,
J¼7.5 Hz, 2H), 7.12 (d, J¼7.5 Hz, 2H), 4.20 (s, 2H), 2.31 (s, 3H), 1.35 (s,
9H). 13C NMR (125 MHz, CDCl3)
165.5, 149.0, 147.6, 141.3, 136.8,
125.6, 121.2, 119.6, 114.6, 112.6, 109.7, 55.0, 35.2, 21.3. MS (ESI):
276 [MþNa]þ; HRMS (ESI) calcd for C16H15NNaO2 [MþNa]þ:
d
276.0095; found: 276.0098. IR (neat)
n
2965, 2926, 2357, 2341,
131.8, 129.4, 128.8, 122.2, 116.3, 109.5, 34.8, 31.7, 21.0. MS (ESI): 302
1604, 1585, 1570, 1492, 1452, 1433, 1256, 1191, 1146, 1051, 968,
[MþNa]þ; HRMS (ESI) calcd for C19H21NNaO [MþNa]þ: 302.1515;
840, 796 cmꢁ1
.
found: 318.1523. IR (neat) n 2965, 2352, 2329, 1573, 1520, 1483,
1427, 1363, 1264, 1124, 1079, 1062, 958, 878, 807 cmꢁ1
.
4.2.12. Compound 4l yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
7.46 (s, 1H), 7.30 (d, J¼8.5 Hz, 1H), 7.22e7.19 (m, 1H), 7.15 (d,
J¼7.5 Hz, 2H), 7.06 (d, J¼8.0 Hz, 2H), 4.19 (s, 2H), 2.43 (s, 3H), 2.31
(s, 3H). 13C NMR (125 MHz, CDCl3)
165.3, 149.3, 141.6, 138.4,
d
4.2.19. Compound 4s yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
d
7.71 (s, 1H), 7.38e7.31 (m, 4H), 7.00 (t, J¼8.5 Hz, 2H), 4.20 (s, 2H),
d
1.35 (s, 9H). 13C NMR (125 MHz, CDCl3)
d
165.0, 162.0 (d,
134.8, 133.8, 129.6, 128.6, 127.9, 125.9, 125.6, 119.7, 109.7, 35.2,
JCeF¼244.125 Hz), 149.0, 147.8, 141.2, 130.6 (d, JCeF¼3.25 Hz), 130.5
(d, JCeF¼8 Hz), 122.4, 116.3, 115.6 (d, JCeF¼21.375 Hz), 109.5, 34.8,
34.4, 31.7. MS (ESI): 306 [MþNa]þ; HRMS (ESI) calcd for
21.33, 21.26. MS (ESI): 260 [MþNa]þ; HRMS (ESI) calcd for
C
16H15NNaO [MþNa]þ: 260.1046; found: 260.1045. IR (neat)
n
2954, 2920, 2357, 2318, 1573, 1478, 1261, 1191, 1146, 965, 843,
C
18H18FNNaO [MþNa]þ: 306.1265; found: 306.1270. IR (neat)
n
799 cmꢁ1
.
2954, 2901, 2868, 1577, 1507, 1477, 1424, 1361, 1275, 1222, 1152,
1123, 960, 932, 879, 861, 834, 809, 780, 740 cmꢁ1
4.2.20. Compound 4t yellow solid; mp: 48e49 ꢀC. 1H NMR
.
4.2.13. Compound 4m yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS) 7.45 (s, 1H), 7.29 (d, J¼8.5 Hz, 1H), 7.24 (d, J¼8.0 Hz, 2H), 7.13
(d, J¼8.0 Hz, 2H), 7.08e7.05 (m, 1H), 4.19 (s, 2H), 2.42 (s, 3H), 2.31 (s,
3H). 13C NMR (125 MHz, CDCl3)
165.5, 149.3, 141.6, 136.9, 133.9,
d
(500 MHz, CDCl3, TMS) d 7.40e7.34 (m, 6H), 7.31e7.27 (m, 1H), 7.02
d
(td, J¼7.5,1.0 Hz,1H), 4.26 (s, 2H). 13C NMR (125 MHz, CDCl3)
d 167.1,
131.8, 129.5, 128.9, 125.7, 119.7, 109.8, 34.9, 21.4, 21.0. MS (ESI): 238
159.9 (d, JCeF¼238.625 Hz), 147.4, 142.2 (d, JCeF¼13.125 Hz), 134.5,
128.9 (d, JCeF¼15.0 Hz), 127.4, 112.3 (d, JCeF¼26.125 Hz), 110.7 (d,
JCeF¼10.0 Hz), 106.3 (d, JCeF¼25.375 Hz), 35.3. MS (ESI): 228
[MþH]þ; HRMS (ESI) calcd for C14H10FNO [MþH]þ: 228.0819,
[MþH]þ; HRMS (ESI) calcd for C16H16NO [MþH]þ: 238.1226, found
238.1236. IR (neat)
n 3014, 1567, 1427, 1331, 1262, 1060, 1033, 959,
906, 861, 798, 731 cmꢁ1
.
found.228.0820. IR (neat)
807, 751, 714 cmꢁ1
n 3080, 1732, 1576, 1470, 1235, 1006, 856,
4.2.14. Compound 4n yellow solid; mp: 43e44 ꢀC. 1H NMR
.
(500 MHz, CDCl3, TMS)
d
7.47 (s, 1H), 7.32 (d, J¼8.0 Hz, 1H),
7.30e7.24 (m, 1H), 7.13 (d, J¼8.0 Hz, 1H), 7.10e7.07 (m, 2H), 6.95 (td,
4.2.21. Compound 4u yellow solid; mp: 53e54 ꢀC. 1H NMR
(500 MHz, CDCl3, TMS)
7.35 (d, J¼8.5 Hz, 2H), 7.28 (d, J¼8.0 Hz,
2H), 7.00 (t, J¼8.5 Hz,1H), 6.88 (d, J¼8.0 Hz, 2H), 4.18 (s, 2H), 3.77 (s,
3H). 13C NMR (125 MHz, CDCl3)
J¼8.0, 2.0 Hz, 1H), 4.22 (s, 2H), 2.43 (s, 3H). 13C NMR (125 MHz,
d
CDCl3)
d
164.4, 162.9 (d, JCeF¼245.0 Hz), 149.2, 141.4, 137.2 (d,
JCeF¼7.5 Hz), 134.1, 130.2 (d, JCeF¼8.25 Hz), 125.9, 124.6 (d,
JCeF¼2.875 Hz), 119.8, 116.0 (d, JCeF¼21.75 Hz), 114.2 (d,
JCeF¼20.875 Hz), 109.8, 34.9 (d, JCeF¼1.5 Hz), 21.3. MS (ESI): 264
[MþNa]þ; HRMS (ESI) calcd for C15H12FNNaO [MþNa]þ: 264.0795;
d
167.4, 159.8 (d, JCeF¼238.5 Hz),
158.9, 147.3, 142.1 (d, JCeF¼13.0 Hz), 130.0, 126.4, 114.2, 112.1 (d,
JCeF¼26.125 Hz), 110.6 (d, JCeF¼10 Hz), 106.2 (d, JCeF¼25.5 Hz), 55.2,
34.4. MS (ESI): 280 [MþNa]þ; HRMS (ESI) calcd for C15H12FNNaO2
found: 264.0799. IR (neat)
n
2921, 2849, 1590, 1567, 1484, 1444,
[MþNa]þ: 280.0744; found: 280.0749. IR (neat)
n 2999, 2959, 2919,
2352, 2341, 1615, 1568, 1511, 1483, 1438, 1245, 1174, 1124, 1031, 968,
1259, 1239, 1186, 1139, 896, 841, 796 cmꢁ1
.
944, 907, 854, 817, 809 cmꢁ1
.
4.2.15. Compound 4o yellow solid; mp: 67e68 ꢀC. 1H NMR
(500 MHz, CDCl3, TMS)
d 7.46 (s, 1H), 7.33e7.30 (m, 3H), 7.08 (d,
4.2.22. Compound 4v yellow solid; mp: 51e52 ꢀC. 1H NMR
J¼8.5 Hz, 1H), 7.02e6.98 (m, 2H), 4.19 (s, 2H), 2.42 (s, 3H). 13C NMR
(500 MHz, CDCl3, TMS) 7.36e7.33 (m, 2H), 7.25 (d, J¼8.0 Hz, 2H),
7.15 (d, J¼8.0 Hz, 2H), 6.99 (td, J¼9.0, 2.0 Hz, 1H), 4.20 (s, 2H), 2.32
(s, 3H). 13C NMR (125 MHz, CDCl3)
d
(125 MHz, CDCl3)
d
164.9, 162.0 (d, JCeF¼244.125 Hz), 149.2, 141.4,
134.0, 130.5 (d, JCeF¼8.0 Hz), 125.7, 119.7, 115.6 (d, JCeF¼21.375 Hz),
d
167.3, 169.8 (d, JCeF¼238.75
109.7, 34.4, 21.3. MS (ESI): 264 [MþNa]þ; HRMS (ESI) calcd for
Hz), 147.3, 142.2 (d, JCeF¼13 Hz), 137.0, 131.4, 129.5, 128.8, 112.1 (d,
JCeF¼26.125 Hz), 110.6 (d, JCeF¼10 Hz), 106.2 (d, JCeF¼25.5 Hz), 34.9,
21.0. MS (ESI): 264 [MþNa]þ; HRMS (ESI) calcd for C15H12FNNaO
C
15H12FNNaO [MþNa]þ: 264.0795; found: 264.0800. IR (neat)
n
2971, 2926, 2369, 1613, 1565, 1506, 1256, 1219, 1185, 1141, 963, 903,
834, 826, 798 cmꢁ1
.
[MþNa]þ: 264.0795; found: 264.0798. IR (neat)
n 3080, 3027, 2928,
2862, 1623, 1607, 1567, 1511, 1474, 1434, 1272, 1245, 1126, 969, 942,
4.2.16. Compound 4p yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
906, 856, 806, 775, 765 cmꢁ1
.
d
7.71 (s, 1H), 7.36e7.30 (m, 6H), 7.26e7.22 (m, 2H), 4.23 (s, 2H), 1.35
(s, 9H). 13C NMR (125 MHz, CDCl3)
d
165.2, 149.0, 147.6, 141.3, 134.9,
4.2.23. Compound 4w yellow solid; mp: 52e53 ꢀC. 1H NMR
128.9, 128.7, 127.2, 122.2, 116.3, 109.5, 35.2, 34.8, 31.7. MS (ESI): 288
(300 MHz, CDCl3, TMS) 7.41e7.32 (m, 4H), 7.07e7.00 (m, 3H), 4.23
d
[MþNa]þ; HRMS (ESI) calcd for C18H19NNaO [MþNa]þ: 288.1359;
(s, 2H). 13C NMR (125 MHz, CDCl3)
d
166.9, 162.1 (d,
Please cite this article in press as: Ji, Y.-Y.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.07.030

Y.-Y. Ji et al. / Tetrahedron xxx (2015) 1e6
5
JCeF¼244.625 Hz), 159.9 (d, JCeF¼239.375 Hz), 147.2, 141.5, 130.6 (d,
276.0802. IR (neat)
n
2968, 2935, 2372, 2313, 1603, 1554, 1501, 1222,
J¼8.125 Hz), 129.9, 115.8 (d, JCeF¼21.375 Hz), 112.59 (d,
J¼26.125 Hz), 112.57 (d, JCeF¼26.125 Hz), 110.82 (d, JCeF¼10 Hz),
110.81 (d, J¼9.875 Hz), 106.2 (d, JCeF¼25.625 Hz), 34.4. MS (ESI):
246 [MþH]þ; HRMS (ESI) calcd for C17H9FNO [MþH]þ: 246.0714;
1109, 1050, 944, 828, 785 cmꢁ1
.
4.2.31. Compound 4ae yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS)
d
7.53 (dd, J¼8.5, 5.5 Hz, 2H), 7.34e7.31 (m, 4H), 7.27e7.24 (m,
found: 246.0710. IR (neat)
n
2981, 2941, 2352, 1567, 1504, 1474,
1H), 7.17 (s, 1H), 7.06 (t, J¼8.5 Hz, 2H), 4.15 (s, 2H). 13C NMR
1222, 1133, 973, 907, 872, 834, 803 cmꢁ1
.
(125 MHz, CDCl3)
d
162.5, 162.4 (d, JCeF¼247.0 Hz), 150.6, 135.4,
128.7 (d, JCeF¼6.125 Hz), 127.0, 125.8 (d, JCeF¼8.125 Hz), 124.3 (d,
JCeF¼3.375 Hz), 121.6 (d, JCeF¼1.0 Hz), 115.8 (d, JCeF¼21.875 Hz),
34.7. MS (ESI): 276 [MþNa]þ; HRMS (ESI) calcd for C16H12FNNaO
4.2.24. Compound 4x7g yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS)
d
7.54 (d, J¼8.5 Hz, 1H), 7.37e7.32 (m, 4H), 7.28e7.25 (m, 2H),
7.10 (d, J¼8.5 Hz, 1H), 4.24 (s, 2H), 2.45 (s, 3H). 13C NMR (125 MHz,
[MþNa]þ: 276.0795; found: 276.0805. IR (neat)
n 3067, 3034, 2921,
CDCl3)
d
164.6, 151.4, 139.2, 135.02, 134.97, 129.0, 128.8, 127.2, 125.3,
1597, 1580, 1554, 1497, 1451, 1229, 1162, 1113, 1056, 973, 940, 834,
119.1, 110.6, 35.3, 21.6.
821, 728, 692 cmꢁ1
.
4.2.25. Compound 4y yellow liquid. 1H NMR (500 MHz, CDCl3,
4.2.32. Compound 4af yellow solid; mp: 57e58 ꢀC. 1H NMR
TMS)
7.09 (d, J¼8.0 Hz, 1H), 6.86 (d, J¼8.5 Hz, 2H), 4.17 (s, 2H), 3.77 (s,
3H), 2.44 (s, 3H). 13C NMR (125 MHz, CDCl3)
164.9, 158.8, 151.3,
d
7.53 (d, J¼8.0 Hz, 1H), 7.28 (d, J¼8.5 Hz, 2H), 7.24 (s, 1H),
(500 MHz, CDCl3, TMS) 7.54 (dd, J¼8.5, 5.5 Hz, 2H), 7.26 (d,
J¼8.5 Hz, 2H), 7.16 (s, 1H), 7.06 (t, J¼8.5 Hz, 2H), 6.87 (d, J¼8.5 Hz,
2H), 4.09 (s, 2H), 3.77 (s, 3H). 13C NMR (125 MHz, CDCl3)
162.9,
d
d
d
139.1, 134.9, 130.0, 126.9, 125.2, 119.0, 114.2, 110.5, 55.2, 34.3,
162.4 (d, JCeF¼246.875 Hz), 158.7, 150.5, 129.8, 127.4, 125.8 (d,
JCeF¼8 Hz), 124.4, 121.6, 115.8 (d, JCeF¼21.875 Hz), 114.1, 55.2, 33.8.
MS (ESI): 306 [MþNa]þ; HRMS (ESI) calcd for C17H14NNaO2
21.6. MS (ESI): 254 [MþH]þ; HRMS (ESI) calcd for C16H16NO2
[MþH]þ: 254.1176; found: 254.1169. IR (neat)
n 3002, 2961, 2920,
2833, 2359, 2337, 1613, 1567, 1510, 1487, 1458, 1426, 1342, 1301,
1244, 1173, 1148, 1109, 1034, 941, 895, 809, 778, 756, 733,
[MþNa]þ: 306.0901; found: 306.0898. IR (neat)
n 3007, 2961, 2842,
1550, 1501, 1467, 1295, 1242, 1179, 1119, 839, 823, 816 cmꢁ1
.
697 cmꢁ1
.
4.2.33. Compound 4ag yellow solid; mp: 58e59 ꢀC. 1H NMR
(500 MHz, CDCl3, TMS)
7.52 (dd, J¼8.0, 5.5 Hz, 2H), 7.22 (d,
J¼7.5 Hz, 2H), 7.16 (s, 1H), 7.13 (d, J¼7.5 Hz, 2H), 7.05 (t, J¼8.0 Hz,
2H), 4.10 (s, 2H), 2.31 (s, 3H). 13C NMR (125 MHz, CDCl3)
162.7,
4.2.26. Compound 4z yellow liquid. 1H NMR (500 MHz, CDCl3, TMS)
7.53 (d, J¼8.5 Hz, 1H), 7.24 (d, J¼8.0 Hz, 2H), 7.23 (s, 1H), 7.13 (d,
J¼8.0 Hz, 2H), 7.08 (dd, J¼8.5, 1.0 Hz, 1H), 4.19 (s, 2H), 2.43 (s, 3H),
2.31 (s, 3H). 13C NMR (125 MHz, CDCl3)
164.8, 151.3, 139.2, 136.8,
d
d
d
d
162.4 (d, JCeF¼246.875 Hz),150.5,136.6,132.3,129.3,128.6,125.8 (d,
JCeF¼8.125 Hz), 124.4 (d, JCeF¼3.375 Hz), 121.6 (d, JCeF¼1 Hz), 115.8
(d, JCeF¼21.875 Hz), 34.2, 20.9. MS (ESI): 290 [MþNa]þ; HRMS (ESI)
calcd for C17H14FNNaO [MþNa]þ: 290.0952; found: 290.0949. IR
134.9, 131.8, 129.4, 128.8, 125.2, 119.0, 110.6, 34.8, 21.6, 21.0. MS
(ESI): 238 [MþH]þ; HRMS (ESI) calcd for C16H16NO [MþH]þ:
238.1226; found: 238.1222. IR (neat) n 3027, 2915, 2862, 2359, 2332,
1610, 1567, 1511, 1484, 1454, 1428, 1335, 1245, 1146, 1109, 942, 894,
(neat) n .
2915, 1557, 1507, 1232, 1159, 1106, 1046, 940, 829, 775 cmꢁ1
852, 806, 768, 728 cmꢁ1
.
4.2.34. Compound 4ah yellow solid; mp: 63e64 ꢀC. 1H NMR
(500 MHz, CDCl3, TMS)
7.47 (d, J¼8.0 Hz, 2H), 7.35e7.30 (m, 4H),
7.26e7.22 (m, 1H), 7.18 (s, 1H), 7.17 (d, J¼9.0 Hz, 2H), 4.15 (s, 2H),
2.34 (s, 3H). 13C NMR (125 MHz, CDCl3)
162.1, 151.6, 138.1, 135.5,
4.2.27. Compound 4aa10 yellow solid. 1H NMR (500 MHz, CDCl3,
TMS) 7.58e7.56 (m, 2H), 7.38e7.31 (m, 6H), 7.29e7.22 (m, 3H),
4.16 (s, 2H). 13C NMR (125 MHz, CDCl3)
162.5, 151.4, 135.4, 128.73,
d
d
d
d
128.65, 128.1, 128.0, 127.0, 124.0, 122.0, 34.7.
129.4, 128.7, 128.6, 126.9, 125.3, 123.9, 121.3, 34.7, 21.2. MS (ESI) 250
[MþH]þ; HRMS (EI): calcd for C17H16NO [MþH]þ: 250.1226, found:
4.2.28. Compound 4ab yellow solid; mp: 76e77 ꢀC. 1H NMR
250.1244. IR (neat) n 3318, 3252, 3034, 2941, 1693, 1643, 1603, 1520,
(500 MHz, CDCl3, TMS)
2H), 7.28e7.22 (m, 4H), 6.87 (d, J¼8.0 Hz, 2H), 4.10 (s, 2H), 3.76 (s,
3H). 13C NMR (125 MHz, CDCl3)
162.9, 158.6, 151.3, 129.8, 128.7,
d
7.57 (d, J¼8.0 Hz, 2H), 7.36 (t, J¼7.5 Hz,
1494, 1451, 1355, 1322, 1298, 1242, 1159, 1123, 1030, 1013, 911, 859,
809, 783, 718, 690 cmꢁ1
.
d
128.1, 128.0, 127.4, 123.9, 121.9, 114.1, 55.1, 33.8. MS (ESI): 288
4.2.35. Compound 4ai yellow solid; mp: 78e79 ꢀC. 1H NMR
(500 MHz, CDCl3, TMS)
7.46 (d, J¼8.0 Hz, 2H), 7.25 (t, J¼7.5 Hz,
2H), 7.171 (d, J¼7.5 Hz, 2H), 7.166 (s, 1H), 6.86 (d, J¼8.0 Hz, 2H), 4.08
(s, 2H), 3.76 (s, 3H), 2.34 (s, 3H). 13C NMR (125 MHz, CDCl3)
162.5,
[MþNa]þ; HRMS (ESI) calcd for C17H15NNaO2 [MþNa]þ:
d
288.0995; found: 288.1004. IR (neat)
n 2981, 2895, 2352, 2332,
1607, 1550, 1504, 1239, 1179, 1116, 1056, 1020, 937, 906, 823, 783,
d
758 cmꢁ1
.
158.6, 151.5, 138.1, 129.8, 129.4, 127.5, 125.3, 123.9, 121.2, 114.1, 55.1,
33.8, 21.2. MS (ESI): 302 [MþNa]þ; HRMS (ESI) calcd for
4.2.29. Compound 4ac yellow solid; mp: 74e75 ꢀC. 1H NMR
C
18H17NNaO2 [MþNa]þ: 302.1151; found: 302.1154. IR (neat)
n 2954,
(500 MHz, CDCl3, TMS)
d
7.57 (d, J¼7.5 Hz, 2H), 7.36 (t, J¼7.5 Hz, 2H),
2908, 2365, 2313, 1610, 1554, 1507, 1428, 1239, 1179, 1027, 977, 812,
7.28e7.22 (m, 4H), 7.13 (d, J¼7.5 Hz, 2H), 4.11 (s, 2H), 2.31 (s, 3H). 13
C
785 cmꢁ1
.
NMR (125 MHz, CDCl3)
d 162.8, 151.3, 136.6, 132.4, 129.3, 128.7,
128.6, 128.1, 128.0, 124.0, 121.9, 34.3, 21.0. MS (ESI): 272 [MþNa]þ;
4.2.36. Compound 4aj yellow solid; mp: 75e76 ꢀC. 1H NMR
HRMS (ESI) calcd for C17H15NNaO [MþNa]þ: 272.1046; found:
(500 MHz, CDCl3, TMS) 7.46 (d, J¼8.0 Hz, 2H), 7.22 (d, J¼8.0 Hz,
2H), 7.17 (s, 1H), 7.16 (d, J¼7.5 Hz, 2H), 7.13 (d, J¼7.5 Hz, 2H), 4.10 (s,
2H), 2.33 (s, 3H), 2.31 (s, 3H). 13C NMR (125 MHz, CDCl3)
162.4,
d
272.1053. IR (neat) n 2915, 2842, 2365, 2313, 1646, 1554, 1511, 1444,
1113, 1060, 973, 944, 897, 828, 771 cmꢁ1
.
d
151.5, 150.0,138.0,136.5,132.4,129.4,129.3,128.6,123.9,121.3, 34.3,
4.2.30. Compound 4ad yellow solid; mp: 73e74 ꢀC. 1H NMR
21.2, 20.9. MS (ESI): 286 [MþNa]þ; HRMS (ESI) calcd for
(500 MHz, CDCl3, TMS)
d
7.56 (d, J¼7.5 Hz, 2H), 7.36 (t, J¼7.5 Hz, 2H),
C
18H17NNaO [MþNa]þ: 286.1202; found: 286.1208. IR (neat)
n 2982,
7.30e7.27 (m, 3H), 7.23 (s, 1H), 7.00 (t, J¼8.5 Hz, 2H), 4.11 (s, 2H). 13
C
2920, 2363, 2335, 1554, 1517, 1506, 1112, 1051, 970, 941, 906,
NMR (125 MHz, CDCl3)
d
162.2, 161.8 (d, JCeF¼243.875 Hz), 151.4,
813 cmꢁ1
.
131.0 (d, JCeF¼3.25 Hz), 130.2 (d, JCeF¼8 Hz), 128.7, 128.2, 127.8,
123.9, 121.9, 115.4 (d, JCeF¼21.25 Hz), 33.8. MS (ESI): 276 [MþNa]þ;
HRMS (ESI) calcd for C16H12FNNaO [MþNa]þ: 276.0795; found:
4.2.37. Compound 4ak yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS) 7.61 (d, J¼6.5 Hz, 1H), 7.36e7.31 (m, 4H), 7.26 (d, J¼6.5 Hz,
d
Please cite this article in press as: Ji, Y.-Y.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.07.030

6
Y.-Y. Ji et al. / Tetrahedron xxx (2015) 1e6
1H), 7.24e7.20 (m, 3H), 7.14 (s,1H), 4.17 (s, 2H), 2.41 (s, 3H). 13C NMR
(125 MHz, CDCl3) 162.1, 150.8, 135.5, 134.7, 131.0, 128.8, 128.7,
References and notes
d
1. For some recent reviews on the direct CeH bond functionalization, please see:
(a) Rossi, R.; Bellina, F.; Lessi, M.; Manzini, C. Adv. Synth. Catal. 2014, 356,
17e117; (b) Bonin, H.; Sauthier, M.; Felpin, F.-X. Adv. Synth. Catal. 2014, 356,
645e671; (c) Daugulis, O. Chem. Heterocycl. Compd. 2012, 48, 21e26; (d) Kuhl,
N.; Hopkinson, M. N.; Wencel-Delord, J.; Glorius, F. Angew. Chem., Int. Ed. 2012,
51, 10236e10254; (e) Engle, K. M.; Mei, T.-S.; Wasa, M.; Yu, J.-Q. Acc. Chem. Res.
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128.1, 127.3, 127.0, 126.7, 126.0, 124.8, 34.7, 21.7. MS (ESI): 272
[MþNa]þ; HRMS (ESI) calcd for C17H15NNaO [MþNa]þ: 272.1046;
found: 272.1043. IR (neat)
n 3066, 3021, 2931, 2858, 1551, 1500,
1430, 1455, 1287, 1222, 1112, 1048, 969, 941, 907, 847, 809, 724, 694,
678 cmꢁ1
.
4.2.38. Compound 4al yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS)
7.61 (d, J¼7.5 Hz, 1H), 7.27 (d, J¼8.0 Hz, 2H), 7.23e7.21 (m,
3H), 7.12 (s, 1H), 6.86 (d, J¼8.0 Hz, 2H), 4.11 (s, 2H), 3.76 (s, 3H), 2.41
(s, 3H). 13C NMR (125 MHz, CDCl3)
162.5, 158.6, 150.7, 134.6, 131.0,
d
d
129.8, 128.9, 128.1, 127.5, 127.3, 126.6, 126.0, 124.7, 114.1, 55.1, 33.8,
21.7. MS (ESI): 302 [MþNa]þ; HRMS (ESI) calcd for C18H17NNaO2
[MþNa]þ: 302.1151; found: 302.1155. IR (neat)
n 2976, 2931, 2897,
2363, 2329, 1702, 1613, 1509, 1247, 1171, 1124, 1031, 941, 904,
826 cmꢁ1
.
4.2.39. Compound 4am yellow liquid. 1H NMR (500 MHz, CDCl3,
TMS) 7.61 (d, J¼6.5 Hz, 1H), 7.24e7.21 (m, 5H), 7.13 (d,
J¼8.0 Hz, 2H), 7.12 (s, 1H), 4.12 (s, 2H), 2.41 (s, 3H), 2.31 (s, 3H).
13C NMR (125 MHz, CDCl3)
162.4, 150.7, 136.6, 134.6, 132.4,
d
3. (a) Chen, W.-X.; Zhang, C.-Y.; Lu, J.-M. J. Chem. Res. 2013, 611e614; (b) Chen, W.-
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2014, 12, 8488e8498.
d
131.0, 129.3, 128.6, 128.1, 127.3, 126.6, 126.0, 124.8, 34.3, 21.7,
21.0. MS (ESI): 286 [MþNa]þ; HRMS (ESI) calcd for C18H17NNaO
[MþNa]þ: 286.1202; found: 286.1203. IR (neat)
n 2982, 2909,
2357, 2329, 1697, 1556, 1514, 1486, 1458, 1126, 1034, 940, 904,
824 cmꢁ1
.
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Acknowledgements
ꢀ
ꢀ
ꢀ
YZ thanks the University Students’ Innovative Undertaking
Training Program for financial support. We thank Mr. Shun-Chao
Yin for his kind help in preparing the revised version.
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Copies of the 1H NMR and 13C NMR spectra of all key in-
termediates and final products. Supplementary data associated
with this article can be found in the online version, at http://
dx.doi.org/10.1016/j.tet.2015.07.030. These data include MOL files
and InChiKeys of the most important compounds described in this
article.
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Please cite this article in press as: Ji, Y.-Y.; et al., Tetrahedron (2015), http://dx.doi.org/10.1016/j.tet.2015.07.030