Regioselective lateral or vinyl C-H lithiation/1,5-retro-Brook rearrangement via quinolyl or pyridyl ring directed deprotonation

Article abstract of DOI:10.1016/j.tet.2013.04.065

A regioselective lateral or vinyl C-H lithiation/1,5-retro-Brook rearrangement via quinolyl or pyridyl ring directed deprotonation has been developed. 16 examples were tested and the corresponding alkyl silanes and E-vinyl silanes were obtained in moderate to good yields.

Full text of DOI:10.1016/j.tet.2013.04.065

Tetrahedron 69 (2013) 5545e5549
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Regioselective lateral or vinyl CeH lithiation/1,5-retro-Brook
rearrangement via quinolyl or pyridyl ring directed deprotonation
,b,
Yongping He a, Bin Ma a, Juan Yang a, Xingang Xie a, Xuegong She a
*
a State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
b State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000,
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:
A regioselective lateral or vinyl CeH lithiation/1,5-retro-Brook rearrangement via quinolyl or pyridyl ring
directed deprotonation has been developed. 16 examples were tested and the corresponding alkyl silanes
and E-vinyl silanes were obtained in moderate to good yields.
Received 28 February 2013
Received in revised form 11 April 2013
Accepted 15 April 2013
Ó 2013 Elsevier Ltd. All rights reserved.
Available online 19 April 2013
Keywords:
Lateral lithiation
Vinyl lithiation
1,5-Retro-Brook rearrangement
Directed deprotonation
Benzyl silanes
Vinyl silanes
1. Introduction
Brook rearrangement via quinolyl or pyridyl ring directed
deprotonation.
Silanes are usually inexpensive, nontoxic, and environmentally
benign, and appropriately substituted organosilanes can undergo
a variety of transformations to form useful derivatives. Among the
strategies for the preparation of silanes, the silylation of CeH bonds
is particularly attractive.1 The complex-induced proximity effect
(CIPE) in deprotonations may serve as a heuristic to discover new
modes for CeH activation, which could be extended to carbanion
chemistry.2 In order to establish a CIPE, the direct metallation
groups (DMGs) should be able to effectively coordinate the alkyl-
lithium species. The relative strength of common DMGs in direct-
ing metallation has already been demonstrated.2a Very recently,
our group have developed a sequence of lateral CeH lithiation/1, 4-
retro-Brook rearrangement via direct deprotonation for preparing
benzyl silanes and trans-vinyl silanes (Scheme 1).3 In our proposal,
Scheme 1. Lithiation/retro-Brook rearrangement of aryloxysilanes.
2. Results and discussion
when the
metallation group), the adjacent
form a carbanion accordingly, which may initiate a 1,5-retro-Brook
reaction to give the corresponding alkyl or vinyl silanes (Scheme
1).4 Herein we report the preliminary research result, which led
to a new regioselective lateral or vinyl CeH lithiation/1,5-retro-
b
-position was substituted by a sDMG (strong direct
Initially, several strong directed metallation groups were in-
vestigated in the presence of aryloxysilanes. When sDMGs, such as
thioether, sulfone were introduced, trace of desired products were
detected (Table 1, entries 1 and 2). Indeed, the best directing groups
tend to have a mixture of the basic properties required for good
coordination to lithium and the acidic properties required for rapid
and efficient deprotonation-it might be called as ‘amphoteric’.5 The
quinolyl or pyridyl ring containing the nitrogen atom functions as
a directing group both for lithium coordination and CeH activation.
b
-carbon will be deprotonated and
* Corresponding author. Tel.: þ86 931 8912276; fax: þ86 931 8912583; e-mail
address: shexg@lzu.edu.cn (X. She).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.04.065

5546
Y. He et al. / Tetrahedron 69 (2013) 5545e5549
Table 1
Table 2
Investigation about directed metallation group
Regioselective lateral CeH Lithiation/1,5-retro-Brook rearrangement of
aryloxysilanes
Entry
1
Substrate
Product
Yield (%)
Entry
Substrate (A)
Product (B)
Yield (%)
75
<10
1
2
2
3
4
<10
<10
da
62
81
78
3
4
5
75
a
No product was observed. PT¼1-phenyl-1H-tetrazole-5-yl.
5
6
85
84
But there was competition reaction between ortho-lithiation of the
pyridyl ring and lateral-lithiation (Table 1, entry 4).6 When the
substrate with a quinolyl ring was treated with 4 equiv of LDA from
ꢀ78 ꢁC to reflux for 24 h, the desired product was obtained in 75%
yield through a lateral CeH lithiation/1,5-retro-Brook rearrange-
ment sequence (Table 1, entry 5).
7
8
83
85
The scope and limitation of the reaction was examined and the
results were shown in Table 2. Aryloxysilane 2a with ortho-methyl
substituent gave the product 2b in 62% yield (Table 2, entry 2),
which structure was confirmed by the X-ray single crystal diffrac-
tion experiment (Fig. 1). It was also found that there was complete
selectivity for the lateral position of quinolyl ring rather than that of
the phenolic group. Reactions of aryloxysilanes containing meta-,
para-substituents, such as methyl, tert-butyl and phenyl on the
phenolic group gave the expected products in satisfactory yields
(Table 2, entries 3e6). The substrate 8a with 6-methoxy quinolyl
ring, the directed ortho-metallation group methoxy hardly had any
effect on deprotonation at the lateral position of the quinolyl ring,
reacted well affording 8b in 85% yield (Table 2, entry 8). In the case
of substrate with 3-methyl substituted quinolyl ring, 9b was ob-
tained in 65% yield presumably due to a slight steric hindrance of
methyl group (Table 2, entry 9). The lateral CeH lithiation/1,5-retro-
Brook rearrangement sequence was also proceeded smoothly when
the phenolic ring was replaced by the naphtholic ring (Table 2,
entry 10).
9
65
54
10
Encouraged by the results of the lateral CeH lithiation/1,5-retro-
Brook rearrangement in the series of substrates A, our attention
was turned to the vinyl CeH lithiation/1,5-retro-Brook rearrange-
ment.7 The result was shown in Table 3. It was found that the re-
action was performed smoothly to give 1d in 62% yield at 0 ꢁC for
1 h, and the process was prompted by increasing the reaction time
and temperature (Table 3, entry 1). Fluorine substituent was also
tolerated herein.8 Fluorine-substituted aryloxysilane 2c underwent
a high-yielding transformation to afford 2d (Table 3, entry 2). It
indicated that the vinyl lithiation process had been much easier.
The X-ray experiment of 2d was confirmed that the substrates did
undergo vinyl CeH lithiation at the vicinal position of quinolyl ring
to provide an E-vinyl silane, which was the thermodynamic prod-
uct (Fig. 2). Examination of chloro-substituted aryloxysilane 3c
gave diisopropylamide-substituted product 3d in 45% yield through
a nucleophilic substitution of chlorine/vinyl lithiation/1,5-retro-
Brook rearrangement sequence (Table 3, entry 3).9 Reaction of
Fig. 1. X-ray of 2b (CCDC 915675).

Y. He et al. / Tetrahedron 69 (2013) 5545e5549
5547
Table 3
Table 4
Regioselective vinyl CeH lithiation/1,5-retro-Brook rearrangement of substrates
Regioselective lithiation/1,5-retro-Brook rearrangement of substrates with pyridyl
ring
Entry
Substrate (C)
Product (D)
Yield (%)
Entry
1
Substrate (E)
Product (F)
Yield
(%)
1
80
62a
78
72
2
2
3
82
45
peak at 489 nm, and the fluorescence intensity decreased re-
markably in the presence of Al3þ or Fe3þ ion. The preliminary result
demonstrated that such vinyl silanes might have potential in
fluorescence probes.11
4
70
a
Reaction was performed at 0 ꢁC for 1 h.
naphthyloxysilane 4c also proceeded well to afford 4d in 70% yield
(Table 3, entry 4).
As mentioned above (Table 1, entry 4), the lateral CeH lithiation/
1,5-retro-Brook rearrangement did not take place at all because of
the ortho-lithiation at the pyridyl ring. Then substrate 1e containing
1, 6-di-substituent pyridyl ring was designed, the expected product
1f was received in 78% yield, which structure was confirmed by the
X-ray experiment (Table 4, entry 1).10 Furthermore, reaction of
substrate 2e proceeded well to provide the desired product 2f in
72% yield. The result suggested that the vinyl-lithiation was given
preference over ortho-lithiation (Table 4, entry 2).
Fig. 3. Fluorescence spectra of 3d (7
m
M) in MeOH; at 25 ꢁC; lex¼418 nm; black, free
3d; red, 3dþAl3þ, in the presence of Al3þ ion (33
m
M); blue, 3dþFe3þ, in the presence of
Fe3þ ion (17
mM).
Considering the strong fluorescence intensity of the E-vinyl si-
lanes, such product as 3d was taken as an example to demonstrate
its fluorescence behaviour (Fig. 3). It showed the strong emission
3. Conclusion
In conclusion, we report a regioselective lateral or vinyl CeH
lithiation/1,5-retro-Brook rearrangement via quinolyl or pyridyl
ring directed deprotonation. Various benzyl silanes and E-vinyl si-
lanes have been prepared directly. Fluorescence behaviour of 3d
has been measured for potential application. Further investigation
and application of the methodology are under way in our lab.
4. Experimental
4.1. General
All commercially available reagents were used without further
purification unless otherwise noted. Solvents were purified and
dried by standard methods prior to use. Column chromatography
was generally performed on silica gel (200e300 mesh). Melting
points were determined with a digital Koffer apparatus and were
uncorrected. The 1H and 13C NMR data were recorded on a Mercury
Plus-300 MHz spectrometer or Bruker AM-400 MHz instrument
using CDCl3 as solvent at room temperature. Chemical shifts are
Fig. 2. X-ray of 2d (CCDC 915671).
reported as d values relative to internal chloroform (d
7.27 for 1H

5548
Y. He et al. / Tetrahedron 69 (2013) 5545e5549
NMR and 77.0 for 13C NMR). High-resolution mass spectra (HRMS)
were obtained on a Bruker Daltonics APEXII47e FT-ICR mass spec-
trometer. Fluorescence responses were recorded on FL2500.
41.9, 34.0, 31.7,27.0, 19.9, 17.5, ꢀ5.4, ꢀ6.0; HRMS (ESIMS) calcd for
C
27H38NOSiþ [MþH]þ 420.2717, found 420.2712.
4.2.5. 3-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)-[1,10-bi-
phenyl]-4-ol (5b). White solid, mp 195e197 ꢁC. Yield: 85% (38 mg).
4.2. General procedure for lithiation/retro-Brook
rearrangement
1H NMR (400 MHz, CDCl3)
d
10.60 (s,1H), 8.24 (d, J¼8.7 Hz,1H), 8.02
(d, J¼8.5 Hz, 1H), 7.78e7.72 (m, 2H), 7.56e7.49 (m, 3H), 7.46 (d,
J¼1.2 Hz, 1H), 7.40 (t, J¼7.6 Hz, 2H), 7.31e7.26 (m, 2H), 7.24 (d,
J¼8.5 Hz, 2H), 6.99 (dd, J¼8.3, 0.7 Hz, 1H), 3.69 (d, J¼17.3 Hz, 1H),
3.50 (dt, J¼17.3,11.7 Hz, 2H), 0.85 (d, J¼0.5 Hz, 9H), 0.26 (s, 3H), 0.22
A solution of aryloxysilane (0.1 mmol) in anhydrous THF (5 mL)
was cooled to ꢀ78 ꢁC under Ar. LDA (0.4 mmol, 4 equiv, 2 M) was
added at ꢀ78 ꢁC slowly under stirring. The mixture was allowed to
warm up to room temperature slowly, then heated to reflux and
refluxed for 24 h and monitored by TLC. When the starting material
was consumed, the resulting mixture was cooled to room tem-
perature and quenched with NH4Cl. The layers were separated and
the aqueous layer was extracted with ethyl acetate (three times).
The combined organic layers were washed with brine, dried over
anhydrous Na2SO4 and filtered. Concentration under reduced
pressure gave a residue, which was purified by flash column
chromatography to afford the product.
(s, 3H); 13C NMR (100 MHz, CDCl3)
d 160.9, 154.6, 146.5, 141.6, 136.7,
133.3, 132.9, 129.9, 128.6, 127.8, 127.7, 127.5, 127.1, 126.5, 126.3,
126.2, 125.3, 122.1, 118.7, 41.9, 29.7, 27.0, 17.6, ꢀ5.4, ꢀ5.9; HRMS
(ESIMS) calcd for C29H34NOSiþ [MþH]þ 440.2404, found 440.2409.
4.2.6. 2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)-3,5-
dimethylphenol (6b). White solid, mp 193e195 ꢁC. Yield: 84%
(33 mg). 1H NMR (400 MHz, CDCl3)
d
10.59 (s, 1H), 8.14 (d, J¼8.4 Hz,
1H), 7.89 (d, J¼8.8 Hz, 1H), 7.75 (t, J¼6.8 Hz, 2H), 7.46 (t, J¼7.6 Hz,
3H), 7.04 (d, J¼8.8 Hz, 1H), 6.49 (d, J¼7.6 Hz, 2H), 3.89 (t, J¼14.4 Hz,
1H), 3.24 (dd, J¼13.2, 3.6 Hz, 1H), 2.99 (dd, J¼14.8, 2.8 Hz, 1H), 2.41
(s, 3H), 2.13 (s, 3H), 0.98 (s, 9H), 0.19 (s, 3H), ꢀ0.10 (s, 3H); 13C NMR
4.2.1. 2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)phenol
(1b). White solid, mp 160e164 ꢁC. Yield: 75% (22 mg). 1H NMR
(400 MHz, CDCl3)
d
10.47 (s, 1H), 8.21 (d, J¼8.6 Hz, 1H), 8.01 (d,
(100 MHz, CDCl3) d 164.0, 155.2, 146.5, 136.9, 136.6, 135.9, 129.9,
J¼8.5 Hz, 1H), 7.78e7.71 (m, 2H), 7.50 (t, J¼7.5 Hz, 1H), 7.25e7.17
(m, 2H), 7.02e6.96 (m, 1H), 6.92 (dd, J¼8.0, 1.3 Hz, 1H), 6.80 (td,
J¼7.5, 1.3 Hz, 1H), 3.65 (d, J¼17.5 Hz, 1H), 3.45 (dt, J¼17.6, 12.1 Hz,
2H), 0.82 (s, 9H), 0.22 (s, 3H), 0.12 (s, 3H); 13C NMR (100 MHz,
128.4, 127.4, 126.3, 125.6, 125.3, 123.5, 123.0, 116.4, 39.4, 27.3, 25.9,
24.8, 20.8, 20.0, 18.2, ꢀ5.3, ꢀ6.6; HRMS (ESIMS) calcd for
C25H34NOSiþ [MþH]þ 392.2404, found 392.2409.
CDCl3)
d
160.9, 154.8, 146.5, 136.7, 132.7, 129.9, 128.9, 127.8, 127.4,
4.2.7. 2-(2-(tert-Butyldimethylsilyl)-2-(6-methylquinolin-2-yl)ethyl)
127.0, 126.3, 126.2, 122.1, 120.3, 118.3, 41.9, 27.0, 17.6, ꢀ5.5, ꢀ6.1;
HRMS (ESIMS) calcd for C23H30NOSiþ [MþH]þ 364.2091, found
364.2083.
phenol (7b). White solid, mp 184e186 ꢁC. Yield: 83% (31 mg). 1H
NMR (400 MHz, CDCl3)
d
10.55 (s, 1H), 8.10 (d, J¼8.6 Hz, 1H), 7.91 (d,
J¼8.5 Hz, 1H), 7.56 (dd, J¼8.6, 1.7 Hz, 1H), 7.50 (s, 1H), 7.20 (dd,
J¼13.6, 4.8 Hz, 2H), 7.03e6.95 (m, 1H), 6.94e6.89 (m, 1H),
6.85e6.76 (m, 1H), 3.64 (d, J¼17.6 Hz, 1H), 3.52 (d, J¼11.8 Hz, 1H),
3.39 (dd, J¼17.6, 11.6 Hz, 1H), 2.52 (s, 3H), 0.83 (s, 9H), 0.23 (s, 3H),
4.2.2. 2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)-4,6-
dimethylphenol (2b). White solid, mp 145e147 ꢁC. Yield: 62%
(24 mg). 1H NMR (400 MHz, CDCl3)
d
10.09 (s, 1H), 8.14 (d, J¼8.6 Hz,
0.13 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 159.9, 154.9, 145.1, 136.0,
1H), 7.89 (d, J¼8.5 Hz, 1H), 7.72 (dd, J¼11.7, 4.6 Hz, 2H), 7.46 (t,
J¼7.5 Hz, 1H), 7.03 (d, J¼8.6 Hz, 1H), 6.79 (s, 1H), 6.66 (s, 1H),
3.89e3.74 (m, 1H), 3.15 (dd, J¼13.0, 3.2 Hz, 1H), 2.86 (dd, J¼14.3,
3.1 Hz, 1H), 2.18 (s, 3H), 2.06 (s, 3H), 0.99 (s, 9H), 0.14 (s, 3H), ꢀ0.14
135.9, 132.8, 132.0, 128.9, 127.4, 127.1, 126.3, 126.3, 122.0, 120.2,
118.4, 41.7, 27.0, 21.4, 17.6, 14.1, ꢀ5.5, ꢀ6.1; HRMS (ESIMS) calcd for
C24H32NOSiþ [MþH]þ 378.2248, found 378.2246.
(s, 3H); 13C NMR (100 MHz, CDCl3)
d
163.7, 150.7, 146.7, 135.8, 129.7,
4.2.8. 2-(2-(tert-Butyldimethylsilyl)-2-(6-methoxyquinolin-2-yl)
ethyl)phenol (8b). White solid, mp 167e170 ꢁC. Yield: 85% (33 mg).
129.6, 129.2, 128.5, 127.6, 127.5, 127.4, 126.4, 126.3, 125.5, 123.5, 41.9,
27.6, 27.2, 27.0, 20.5, 18.2, 16.4, ꢀ5.1, ꢀ6.7; HRMS (ESIMS) calcd for
C25H34NOSiþ [MþH]þ 392.2404, found 392.2410.
1H NMR (400 MHz, CDCl3)
d
10.51 (s, 1H), 8.10 (d, J¼9.2 Hz, 1H), 7.89
(d, J¼8.5 Hz,1H), 7.37 (dd, J¼9.2, 2.7 Hz,1H), 7.19 (dd, J¼12.0, 4.8 Hz,
2H), 7.04e6.95 (m, 2H), 6.91 (d, J¼7.1 Hz, 1H), 6.80 (t, J¼7.3 Hz, 1H),
3.91 (s, 3H), 3.61 (d, J¼17.5 Hz, 1H), 3.48 (d, J¼12.0 Hz, 1H), 3.36 (dd,
J¼17.5, 11.7 Hz, 1H), 0.82 (s, 9H), 0.21 (s, 3H), 0.12 (s, 3H); 13C NMR
4.2.3. 2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)-4-
methylphenol (3b). White solid; mp 182e185 ꢁC. Yield: 81%
(30 mg). 1H NMR (400 MHz, CDCl3)
d
8.30e8.15 (m, 1H), 8.23e8.17
(100 MHz, CDCl3) d 158.3, 157.5, 154.8, 142.5, 135.5, 132.8, 129.1,
(m, 1H), 8.00 (d, J¼8.5 Hz, 1H), 8.00 (d, J¼8.5 Hz, 1H), 7.74 (d,
J¼7.5 Hz, 2H), 7.74 (d, J¼7.5 Hz, 2H), 7.49 (td, J¼7.3, 1.0 Hz, 1H), 7.49
(td, J¼7.3, 1.0 Hz, 1H), 7.23 (d, J¼8.5 Hz, 1H), 7.23 (d, J¼8.5 Hz, 1H),
7.00 (d, J¼1.8 Hz, 1H), 7.00 (d, J¼1.8 Hz, 1H), 6.85e6.73 (m, 2H),
6.84e6.77 (m, 2H), 3.64 (d, J¼17.0 Hz,1H), 3.44 (m, 2H), 2.22 (s, 3H),
0.83 (s, 9H), 0.22 (s, 3H), 0.14 (s, 3H); 13C NMR (100 MHz, CDCl3)
128.9, 128.0, 126.3, 122.3, 122.1, 120.2, 118.3, 105.4, 55.5, 41.5, 27.0,
19.7, 17.6, ꢀ5.5, ꢀ6.1; HRMS (ESIMS) calcd for C24H32NO2Siþ
[MþH]þ 394.2197, found 394.2201.
4.2.9. 2-(2-(tert-Butyldimethylsilyl)-2-(3-methylquinolin-2-yl)ethyl)
phenol (9b). White solid, mp 144e146 ꢁC. Yield: 65% (25 mg). 1H
d
161.0, 152.4, 146.6, 136.6, 132.4, 130.9, 129.8, 129.2, 127.8, 127.4,
NMR (400 MHz, CDCl3)
d
10.92 (s, 1H), 8.25 (d, J¼8.5 Hz, 1H), 7.76 (s,
127.0, 126.8, 126.1, 122.1, 118.0, 41.8, 29.7, 27.0, 19.7, 17.6, ꢀ5.5, ꢀ6.1;
HRMS (ESIMS) calcd for C24H32NOSiþ [MþH]þ 378.2248, found
378.2243.
1H), 7.73e7.60 (m, 2H), 7.46 (t, J¼7.5 Hz, 1H), 7.27 (d, J¼7.5 Hz, 1H),
7.09e6.97 (m, 2H), 6.86 (t, J¼7.3 Hz,1H), 3.61 (d, J¼11.2 Hz,1H), 3.49
(d, J¼18.4 Hz, 1H), 3.31 (dd, J¼18.4, 11.4 Hz, 1H), 2.41 (s, 3H), 0.87 (s,
9H), 0.27 (s, 3H), 0.19 (s, 3H); 13C NMR (100 MHz, CDCl3)
d 156.0,
4.2.4. 4-(tert-Butyl)-2-(2-(tert-butyldimethylsilyl)-2-(quinolin-2-yl)
155.0,145.1,136.1,132.9, 130.1,128.9,128.8,127.4,127.2,126.6, 126.4,
126.0, 120.1, 118.3, 39.7, 27.0, 19.1, 18.9, 17.6, ꢀ5.5, ꢀ6.1; HRMS
(ESIMS) calcd for C24H32NOSiþ [MþH]þ 378.2248, found 378.2250.
ethyl)phenol (4b). White solid, mp 184e187 ꢁC. Yield: 78% (32 mg).
1H NMR (400 MHz, CDCl3)
d
8.20 (d, J¼9.0 Hz, 1H), 7.96 (d, J¼8.5 Hz,
1H), 7.12e7.68 (m, 2H), 7.47 (td, J¼6 Hz, 1H), 7.25e7.19 (m, 2H),
6.85e6.73 (dd, J¼3.0, 9.0 Hz, 2H), 6.86 (d, J¼5.7 Hz, 1H), 3.64 (d,
J¼17.0 Hz, 1H), 3.52e3.40 (m, 2H), 1.28 (s, 9H), 0.80 (s, 9H), 0.21 (s,
4.2.10. 1-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)ethyl)naph-
thalen-2-ol (10b). White solid, mp 97e101 ꢁC. Yield: 54% (22 mg).
3H), 0.19 (s, 3H); 13C NMR (100 MHz, CDCl3)
d
161.0, 152.3, 146.5,
1H NMR (400 MHz, CDCl3)
(t, J¼8.5 Hz, 2H), 7.74 (dd, J¼11.5, 4.5 Hz, 3H), 7.53 (t, J¼8.2 Hz, 3H),
d
11.43 (s,1H), 8.29 (d, J¼8.4 Hz,1H), 8.01
142.6, 136.6, 132.0, 129.8, 127.7, 127.4, 127.0, 126.1, 123.1, 122.1, 117.5,

Y. He et al. / Tetrahedron 69 (2013) 5545e5549
5549
7.38 (d, J¼7.7 Hz, 1H), 7.23 (dd, J¼8.5, 4.6 Hz, 2H), 4.21 (dd, J¼11.2,
1.8 Hz, 1H), 3.93 (dd, J¼18.4, 11.2 Hz, 1H), 3.76 (dd, J¼18.3, 1.6 Hz,
1H), 0.87 (s, 9H), 0.46 (s, 3H), ꢀ0.31 (s, 3H); 13C NMR (100 MHz,
(t, J¼7.7 Hz, 1H), 7.13 (dd, J¼14.2, 7.2 Hz, 3H), 6.88 (s, 1H), 6.73 (s,
1H), 6.58 (d, J¼3.7 Hz, 2H), 0.89 (s, 9H), 0.25 (s, 6H); 13C NMR
(100 MHz, CDCl3)
d 161.3, 154.4, 147.8, 143.5, 134.0, 136.5, 129.2,
CDCl3)
d
161.3, 153.0, 146.4, 136.8, 133.9, 129.9, 129.8, 128.9, 128.5,
128.5, 126.5, 123.8, 121.3, 119.0, 117.9, 26.8, 17.6, ꢀ5.2; HRMS
127.7, 127.5, 127.0, 126.2, 124.8, 124.5, 123.8, 122.3, 122.2, 120.9, 40.1,
26.5, 18.1, 17.3, ꢀ4.5, ꢀ5.5; HRMS (ESIMS) calcd for C27H32NOSiþ
[MþH]þ 414.2248, found 414.2243.
(ESIMS) calcd for C19H26NOSiþ [MþH]þ 312.1778, found 312.1774.
Acknowledgements
4.2.11. (E)-2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)vinyl)phe-
We are grateful for the generous financial support by the MOST
(2010CB833200), the NSFC (21125207, 21072086, 21102062), Pro-
gram 111, and the Fundamental Research Funds for the Central
Universities (lzujbky-2011-76).
nol (1d). White solid, mp 142e144 ꢁC. Yield: 80% (29 mg). 1H NMR
(400 MHz, CDCl3)
d
10.27 (s, 1H), 8.11 (d, J¼8.4 Hz, 1H), 8.02 (d,
J¼8.5 Hz, 1H), 7.77e7.67 (m, 2H), 7.50 (t, J¼7.5 Hz, 1H), 7.16 (d,
J¼8.5 Hz, 1H), 7.11 (s, 1H), 7.01 (t, J¼7.7 Hz, 1H), 6.96 (d, J¼7.8 Hz,
1H), 6.84 (d, J¼8.1 Hz, 1H), 6.72 (t, J¼7.4 Hz,1H), 0.90 (s, 9H), 0.28 (s,
6H); 13C NMR (100 MHz, CDCl3)
d 153.8, 152.9, 145.8, 139.8, 137.6,
Supplementary data
136.5, 133.8, 129.9, 129.2, 128.7, 128.0, 127.5, 126.5, 126.3, 121.6,
119.7, 119.3, 26.9, 17.6, ꢀ5.0; HRMS (ESIMS) calcd for C23H28NOSiþ
[MþH]þ 362.1935, found 362.1937.
NMR spectra (1H and 13C) for all products. X-ray ORTEP illus-
tration of 2b, 2d and 1f, fluorescence spectra of 3d. This material is
available free of charge. Supplementary data associated with this
article can be found in the online version, at http://dx.doi.org/
10.1016/j.tet.2013.04.065. These data include MOL files and InChi-
Keys of the most important compounds described in this article.
4.2.12. (E)-2-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)vinyl)-4-
fluorophenol (2d). Red solid, mp 163e165 ꢁC. Yield: 82% (31 mg). 1H
NMR (400 MHz, CDCl3)
d
10.66 (s, 1H), 8.09 (d, J¼8.4 Hz, 2H), 7.78
(d, J¼8.0 Hz, 1H), 7.71 (t, J¼7.2 Hz, 1H), 7.52 (t, J¼7.7 Hz, 1H), 7.24 (d,
J¼8.5 Hz, 1H), 7.11 (s, 1H), 6.63e6.53 (m, 3H), 0.91 (s, 9H), 0.28 (s,
References and notes
6H); 13C NMR (100 MHz, CDCl3)
d 161.6, 157.2, 154.8, 150.4, 146.3,
1. (a) Sakakura, T.; Tokunaga, Y.; Sodeyama, T.; Tnanka, M. Chem. Lett. 1987,
2375e2378; (b) Uchimaru, Y.; Tanaka, M. Organometallics 1993, 12, 2065e2069;
(c) Ezbiansky, K.; Sining, D. J.; Zayes, R.; Berry, D. H. Organometallics 1998, 17,
1455e1457; (d) Kakiuchi, F.; Matsumoto, M. J. Organomet. Chem. 2003, 686,
134e144; (e) Kakiuchi, F.; Tsuchiya, K. J. Am. Chem. Soc. 2004, 126,
12792e12793; (f) Rendler, S.; Oestreich, M. J. Am. Chem. Soc. 2007, 129,
502e503; (g) Simmons, E. M.; Hartwig, J. F. J. Am. Chem. Soc. 2010, 132,
17092e17095; (h) Klare, H. F. T.; Oestreich, M.; Ito, J.; Nishiyama, H.; Ohki, Y.;
Tatsumi, K. J. Am. Chem. Soc. 2011, 133, 3312e3315; (i) Mita, T.; Michigami, K.;
Sato, Y. Org. Lett. 2012, 14, 3462e3465.
145.8, 138.8, 136.6, 131.1, 130.1, 128.8, 127.8, 127.6, 126.6, 126.5, 121.7,
119.7, 119.6, 115.2, 115.0, 114.9, 114.6, 26.8, 17.7, ꢀ5.1; HRMS (ESIMS)
calcd for C23H27FNOSiþ [MþH]þ 380.1846, found 380.1846.
4.2.13. (E)-2-(2-(tert-Butyldimethylsilyl)-2-(6-(diisopropylamino)
quinolin-2-yl)vinyl)phenol (3d). Yellow solid, mp 133e135 ꢁC. Yield:
45% (20 mg). 1H NMR (400 MHz, CDCl3)
d
7.89 (d, J¼9.3 Hz, 1H), 7.78
(d, J¼8.5 Hz, 1H), 7.42 (dd, J¼9.3, 2.7 Hz, 1H), 7.06e7.01 (m, 3H),
7.00e6.95 (m,1H), 6.88 (dd, J¼9.5, 5.4 Hz, 2H), 6.72 (t, J¼7.4 Hz,1H),
3.92 (dt, J¼13.6, 6.8 Hz, 2H),1.31 (d, J¼6.8 Hz,12H), 0.89 (s, 9H), 0.27
2. (a) Baran Group Meeting Directed Metallation: A Survival Guide; (b) Whisler,
M. C.; Snieckus, V.; Beak, P. Angew. Chem., Int. Ed. 2004, 43, 2206e2225 and
references cited therein.
(s, 6H); 13C NMR (100 MHz, CDCl3)
d 160.9, 154.8, 146.5, 136.7, 132.7,
3. He, Y.; Xie, X.; She, X. Tetrahedron 2012, 69, 559e563 For other 1,4-retro-Brook
rearrangements, see: (a) Winter, E.; BrJckner, R. Synlett 1994, 1049e1053; (b)
Jiang, X.-L.; Bailey, W. F. Organometallics 1995, 14, 5704e5707; (c) Simpkins, S.
M. E.; Kariuki, B. M.; Arico, C. S.; Cox, L. R. Org. Lett. 2003, 5, 3971e3974; (d)
Nahm, M. R.; Johnson, J. S. Angew. Chem., Int. Ed. 2005, 44, 2377e2379; (e)
Yamago, S.; Fujita, K.; Miyoshi, M.; Kotani, M.; Yoshida, J. Org. Lett. 2005, 7,
909e911; (f) Nakazaki, A.; Nakai, T.; Tomooka, K. Angew. Chem., Int. Ed. 2006, 45,
2235e2238; (g) Mori, H.; Matsuo, T.; Yoshioka, Y.; Katsumura, S. J. Org. Chem.
2006, 71, 9004e9012; (h) Mori, Y.; Futamura, Y.; Horisaki, K. Angew. Chem., Int.
Ed. 2008, 47, 1091e1093.
4. Clayden, G. In Organolithiums: Selectivity for Synthesis; Baldwin, J. E.; Williams, R. M.,
Eds.; Tetrahedron Organic Chemistry Series; Vol. 23, Chapter 2, pp 28e36.
5. For 1,5-retro-Brook rearrangements, see: (a) Anderson, G.; Cameron, D. W.;
Feutrill, G. I.; Read, R. W. Tetrahedron Lett. 1981, 22, 4347e4348; (b) Clayden, J.;
Watson, D. W.; Chambers, M. Tetrahedron 2005, 61, 3195e3203.
6. For selected studies on ortho-lithiation, see: (a) Kristensen, J.; Vedsø, P. Org. Lett.
2001, 3, 1435e1437; (b) Florio, S.; Capriati, V.; Aggarwa, V.; Salomone, A. Org.
Lett. 2004, 6, 4191e4194; (c) Mofi, M.; Vassilikogannakis, G. Org. Lett. 2005, 7,
3347e3350; (d) Capriati, V.; Florio, S. Org. Lett. 2005, 7, 3749e3752; (e) Mulvey,
R. E.; Mongin, F. Angew. Chem., Int. Ed. 2007, 46, 3802e3824; (f) Sang, Y.; Zhai, H.
J. Org. Chem. 2008, 73, 3589e3592; (g) Affortunato, F.; Florio, S.; Luisi, R. J. Org.
Chem. 2008, 73, 9214e9220; (h) James, C.; Snieckus, V. J. Org. Chem. 2009, 74,
4094e4103.
129.9, 128.9, 128.4, 128.3, 127.7, 127.4, 127.0, 126.3, 126.2, 122.1,
120.3, 118.4, 49.1, 29.7, 27.0, 14.1, ꢀ5.0, ꢀ6.2; HRMS (ESIMS) calcd
for C29H41N2OSiþ [MþH]þ 461.2983, found 461.2987.
4.2.14. (E)-1-(2-(tert-Butyldimethylsilyl)-2-(quinolin-2-yl)vinyl)
naphthalen-2-ol (4d). White solid, mp 85e88 ꢁC. Yield: 70%
(28 mg). 1H NMR (400 MHz, CDCl3)
d
8.15 (d, J¼8.5 Hz, 1H), 7.81 (d,
J¼8.1 Hz, 1H), 7.68 (d, J¼8.9 Hz, 1H), 7.65e7.55 (m, 4H), 7.41 (t,
J¼7.7 Hz, 3H), 7.03 (d, J¼8.8 Hz, 1H), 6.94 (t, J¼7.5 Hz, 1H), 6.45 (d,
J¼7.9 Hz, 1H), 1.12 (s, 9H), 0.41 (s, 6H); 13C NMR (100 MHz, CDCl3)
d
150.4, 144.8, 141.2, 134.6, 131.6, 130.1, 129.0, 128.7, 128.2, 127.6,
126.8, 126.6, 126.1, 126.0, 123.8, 123.5, 120.8, 119.0, 118.8, 114.8,
113.9, 27.3, 17.6, ꢀ3.0, ꢀ3.8; HRMS (ESIMS) calcd for C27H30NOSiþ
[MþH]þ 412.2091 found 412.2095.
4.2.15. 2,20-(Pyridine-2,6-diylbis(2-(tert-butyldimethylsilyl)ethane-
2,1-diyl))diphenol (1f). White solid, mp 136e138 ꢁC. Yield: 78%
7. For vinyl CeH lithiation, see: (a) Reed, M. A.; Chang, M. T.; Snieckus, V. Org. Lett.
2004, 6, 2297e2300; (b) Cotter, J.; O’Shea, D. F. Org. Lett. 2007, 9, 1493e1496; (c)
Tricotet, T.; O’Shea, D. F. J. Am. Chem. Soc. 2009, 131, 3142e3143.
8. Substrate 2-(2-((tert-butyldimethylsilyl)oxy)-5-fluorophenethyl)quinoline was
decomposed on treatment with LDA.
(42 mg). 1H NMR (400 MHz, CDCl3)
d 7.28e7.23 (m, 1H), 7.04e6.96
(m, 4H), 6.74 (dd, J¼11.7, 4.3 Hz, 4H), 6.65 (d, J¼7.7 Hz, 2H),
3.39e3.29 (m, 2H), 3.06 (d, J¼14.4 Hz, 2H), 2.98 (d, J¼12.8 Hz, 2H),
1.06 (s, 18H), 0.14 (s, 6H), ꢀ0.40 (s, 6H); 13C NMR (100 MHz, CDCl3)
9. Borning, C. H.; Burgstrom, F. W. J. Am. Chem. Soc. 1945, 67, 2110e2111.
10. See Supplementary data for details.
d
162.8, 153.9, 135.9, 129.8, 129.0, 127.1, 120.7, 120.2, 116.6, 37.5, 29.9,
27.4, 17.9, ꢀ5.6, ꢀ7.2; HRMS (ESIMS) calcd for C33H50NO2Si2þ
11. (a) Budugu, R.; Geddes, C. D. J. Am. Chem. Soc. 2005, 127, 3635e3641; (b)
Basheer, M. C.; Das, S. Tetrahedron 2007, 63, 1617e1623; (c) Okamoto, A. Tet-
rahedron 2007, 63, 3465e3470; (d) Wang, X.; Li, X.; Schalley, C. A. Org. Biomol.
Chem. 2010, 8, 1017e1026; (e) Mashraqui, S. H. Tetrahedron Lett. 2010, 51,
1306e1308; (f) Sen, S.; Chattopadhyay, P. Analyst 2012, 137, 3975e3981; (g)
Shahoo, S. K.; Sharma, D.; Bera, R. K.; Callan, J. F. Chem. Soc. Rev. 2012, 41,
7195e7227; (h) Karton-Lifshin, N.; Albertazzi, L.; Bentikov, M.; Baran, P. S.;
Shabat, D. J. Am. Chem. Soc. 2012, 134, 20412e20420.
[MþH]þ 548.3375, found 548.3367.
4.2.16. (E)-2-(2-(tert-Butyldimethylsilyl)-2-(pyridin-2-yl)vinyl)phe-
nol (2f). White solid, mp 143e145 ꢁC. Yield: 72% (22 mg). 1H NMR
(400 MHz, CDCl3)
d
10.09 (s, 1H), 8.48 (d, J¼4.0 Hz, 1H), 7.62