Deprotonative metalation of substituted aromatics using mixed lithium-cobalt combinations

Article abstract of DOI:10.1016/j.tet.2010.09.053

The deprotonation of anisole was attempted using different homo- and heteroleptic TMP/Bu mixed lithium-cobalt combinations. Using iodine to intercept the metalated anisole, an optimization of the reaction conditions showed that in THF at room temperature 2 equiv of base were required to suppress the formation of the corresponding 2,2′-dimer. The origin of the dimer was not identified, but its formation was favored with allyl bromide as electrophile. The metalated anisole was efficiently trapped using iodine, anisaldehyde, and chlorodiphenylphosphine, and moderately employing benzophenone, and benzoyl chloride. 1,2-, 1,3-, and 1,4-dimethoxybenzene were similarly converted regioselectively to the corresponding iodides. It was observed that 2-methoxy- and 2,6-dimethoxypyridine were more prone to dimerization than the corresponding benzenes when treated similarly. Involving ethyl benzoate in the metalation-iodination sequence showed that the method was not suitable to functionalize substrates bearing reactive functions.

Full text of DOI:10.1016/j.tet.2010.09.053

Tetrahedron 66 (2010) 8904e8910
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Deprotonative metalation of substituted aromatics using mixed lithiumecobalt
combinations
,
Gandrath Dayaker a, Floris Chevallier a, Philippe C. Gros b, Florence Mongin a
*
a Chimie et Photonique Moléculaires, UMR 6510 CNRS, Université de Rennes 1, Bâtiment 10A, Case 1003, Campus Scientifique de Beaulieu, 35042 Rennes, France
b SOR, SRSMC, CNRS, Nancy Université, Boulevard des Aiguillettes, 54506 Vandœuvre-les-Nancy, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 August 2010
Received in revised form 14 September 2010
Accepted 15 September 2010
Available online 21 September 2010
The deprotonation of anisole was attempted using different homo- and heteroleptic TMP/Bu mixed
lithiumecobalt combinations. Using iodine to intercept the metalated anisole, an optimization of the
reaction conditions showed that in THF at room temperature 2 equiv of base were required to suppress
the formation of the corresponding 2,20-dimer. The origin of the dimer was not identified, but its for-
mation was favored with allyl bromide as electrophile. The metalated anisole was efficiently trapped
using iodine, anisaldehyde, and chlorodiphenylphosphine, and moderately employing benzophenone,
and benzoyl chloride. 1,2-, 1,3-, and 1,4-dimethoxybenzene were similarly converted regioselectively to
the corresponding iodides. It was observed that 2-methoxy- and 2,6-dimethoxypyridine were more
prone to dimerization than the corresponding benzenes when treated similarly. Involving ethyl benzoate
in the metalationeiodination sequence showed that the method was not suitable to functionalize sub-
strates bearing reactive functions.
Keywords:
Bimetallic bases
Deprotonative metalation
Aromatic compounds
Lithium
Cobalt
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
heterocycles and functionalized benzenes using newly developed
lithiumezinc,9 lithiumecadmium,10 and lithiumecopper(I)11 com-
The deprotonative metalation using lithium bases has been
widely used as a powerful method for the regioselective function-
alization of aromatic compounds.1 The use of metal additives in
order to get more efficient or more chemoselective bases (synergic
superbases) is a challenging field. Pioneer studies, respectively,
carried out in the groups of Schlosser2 and Lochmann3 with
LICeKOR, mixture of butyllithium (LIC) and potassium tert-but-
oxide (KOR), and by Caubère, Gros and Fort4 in the pyridine series
with BuLieLiDMAE (DMAE¼2-dimethylaminoethoxide) and
Me3SiCH2LieLiDMAE merged alkyllithiums and alkali-metal alk-
binations, in situ prepared from MCl2$TMEDA (M¼Zn, Cd or Cu,
TMEDA¼N,N,N0,N0-tetramethylethylenediamine) and lithium re-
agents (alkyllithiums or lithium amides). The studies performed
using lithiumezinc and lithiumecadmium combinations have
notably shown that the more efficient bases were obtained by
mixing the metal salt with 3 equiv of LiTMP.9d,10g A main drawback
of the methods developed being the lack of reactivity of such
generated arylmetals in direct trapping with electrophiles, we
turned to other bimetallic combinations in order to identify
candidates able to perform efficient deprotonations, but also to
allow direct functionalizations. We here describe the first aromatic
deproto-metalations using lithiumecobalt combinations.
0
0
oxides. More recently, the use of other (R)n(R )n MLi-type bases,
with M being different from an alkali-metal (e.g., M¼Mg, Al, Cr, Mn,
Cu, Zn), has been described by different groups for their ability to
deprotonate aromatic compounds,5 and notably anisole.6 In 2009,
Klett, Mulvey and co-workers showed that it is possible to design
sodium-iron(II) bases, and extended the ability to deprotonate to
group 8 ate compounds.7 The same year, Wunderlich and Knochel
showed that ferration can be achieved using salt-solubilized
(TMP)2Fe$2MgCl2$4LiCl (TMP¼2,2,6,6-tetramethylpiperidino).8
We recently accomplished the room temperature deproto-
metalation of a large range of substrates including sensitive
2. Results and discussion
The synthesis of organocobalt ate compounds is well-docu-
mented in the literature. They are in general obtained by trans-
metalation of organolithium12 or -magnesium13 reagents with
cobalt(II) halides. Examples are Me3CoLi,12a Me4CoLi2(TMEDA)2,12b
t
and (R3SiCH2)4Co(MgCl)2 (R3Si¼Me3Si, MePh2Si, BuMe2Si).13 The
access to mixed lithiumecobalt amides is far less documented, but
seems possible similarly.14 We first consider the use of CoCl2$TMEDA
chelate15 in order to manipulate a salt less hygroscopic than CoCl2,
but attempts to prepare it failing in giving good microanalyses, we
* Corresponding author. Tel.: þ33 2 2323 6931; fax: þ33 2 2323 6955; e-mail
address: florence.mongin@univ-rennes1.fr (F. Mongin).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.09.053

G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
8905
turned to CoBr2.16 We prepared different lithiumecobalt combina-
tions by mixing the cobalt salt with 3 or 4 equiv of a lithium com-
pound, either LiTMP or mixtures with butyllithium, at 0 ꢀC. We
chose anisole (1) as substrate to check the ability to deprotonate of
the mixtures (Table 1).
a lower 43% yield (entry 6). Extending the reaction time to 4 h did
not bring any improvement (entry 7), but after 20 h the yield was
significantly reduced to 38% (entry 8). The effect of the base amount
was then studied. Using 0.5 equiv of CoBr2 and 1.5 equiv of LiTMP
led to low conversions, whatever the reaction time (entry 9). It was
Table 1
Optimization of anisole metalation using a lithium/cobalt base
OMe
OMe
OMe
1) Li/Co base (x equiv)
THF, conditions
E
+
OMe
2) Electrophile (3x
or 4x equiv), rt
3) Hydrolysis
1
2
3
Entry
1b
Li/Co base (x)
Conditions
25 ꢀC, 2 h
Electrophile (3x or 4x)
2 (E), yield (%)
2a (I), 54
Yield of 3a (%)
CoBr2 (1)þLiTMP (3)
I2 (3)
17
2
3
4
5
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
0 ꢀC, 2 h
0 ꢀC, 4 h
45 ꢀC, 2 h
rt,c 2 h
I2 (3)
I2 (3)
I2 (3)
I2 (3)
2a (I), 12
2a (I), 13
2a (I), 49
2a (I), 59d
5
24
20
de
6
7
8
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
rt, 30 min
rt, 4 h
rt, 20 h
I2 (3)
I2 (3)
I2 (3)
2a (I), 43
2a (I), 57
2a (I), 38
21
de
34
9
CoBr2 (0.5)þLiTMP (1.5)
CoBr2 (1.5)þLiTMP (4.5)
CoBr2 (2)þLiTMP (6)
CoBr2 (2)þLiTMP (6)
rt, 2 to 20 h
rt, 30 min
rt, 2 h
I2 (1.5)
I2 (4.5)
I2 (6)
2a (I), df
2a (I), 54
2a (I), 93
2a (I), 93
df
16
de
5
10
11
12
rt, 30 min
I2 (6)
13
14
15
CoBr2 (1)þBuLi (3)
rt, 2 h
rt, 2 h
rt, 2 h
I2 (3)
I2 (3)
I2 (3)
2a (I), 0
2a (I), 0
2a (I), 0
0
0
0
CoBr2 (1)þLiTMP (1)þBuLi (2)
CoBr2 (1)þLiTMP (2)þBuLi (1)
16
17
18
CoBr2 (1)þLiTMP (1)þBuLi (3)
CoBr2 (1)þLiTMP (2)þBuLi (2)
CoBr2 (1)þLiTMP (3)þBuLi (1)
rt, 2 h
rt, 2 h
rt, 2 h
I2 (4)
I2 (4)
I2 (4)
2a (I), 0
2a (I), 0
2a (I), 19
0
0
35
19
20
CoBr2 (1)þLiTMP (3)
CoBr2 (1)þLiTMP (3)
rt, 2 h
rt, 2 h
H2O (3)
BrCH2CH]CH2 (3)
1 (H), d
14g
38
2b (CH2CH]CH2), 6h
21
CoBr2 (1)þLiTMP (3)
rt, 2 h
(3)
2c
, 14% (16)i
19 (26)i
N
Br
N
a
The rest is in general anisole.
Yields of 9 and 0% using LiTMP and (TMP)2Co, respectively, under the same reaction conditions.
Between 17 and 23 ꢀC.
Yield of 39% in the presence of 1 equiv of TMEDA.
Not quantified.
Low conversion and significant formation of dimer.
Twelve percent using degassed THF.
The high volatility of the compound could be partly responsible for the low yield obtained.
Trapping step performed at 50 ꢀC instead of rt.
b
c
d
e
f
g
h
i
Using LiTMP (1 equiv) or (TMP)2Co (1 equiv, in situ generated
possible to find again the 54% yield already obtained (entry 1) by
using 1.5 equiv of CoBr2 and 4.5 equiv of LiTMP, and a 30 min re-
action time (entry 10). The best result (93% yield) was obtained
using 2 equiv of CoBr2 and 6 equiv of LiTMP (entry 11), allowing to
reduce the reaction time to 30 min (entry 12).
As previously noted in a lesser extent in other bimetallic ser-
ies,9d,10g putative Bu3CoLi$2LiBr (entry 13), Bu2Co(TMP)Li$2LiBr
(entry 14), and BuCo(TMP)2Li$2LiBr (entry 15) alkyl/amino combi-
nations are not able to deprotonate anisole (1). Higher-order ate
compounds being in general more reactive than lower-order
ones,17 reactions were attempted using putative Bu3Co(TMP)
Li2$2LiBr (entry 16), Bu2Co(TMP)2Li2$2LiBr (entry 17), and BuCo
(TMP)3Li2$2LiBr (entry 18). The iodide 2a was only isolated in 19%
yield in the last reaction, due to the competitive formation of 2,20-
dimethoxybiphenyl (3) in 35% yield.
from CoBr2 and 2 equiv of LiTMP) in tetrahydrofuran (THF) at room
temperature for 2 h, and then iodine, anisole (1) was converted into
the 2-iodo derivative 2a in 9 or 0% yield, respectively. In contrast,
when treated with an in situ prepared mixture of CoBr2 (1 equiv)
and LiTMP (3 equiv) at 25 ꢀC for 2 h, anisole (1) was readily ortho-
metalated, a result evidenced with the formation of 2a in 54% yield
after purification (entry 1). Lowering the reaction temperature to
0 ꢀC resulted in a low conversion, even after 4 h reaction time
(entries 2 and 3). When performed at 45 ꢀC, the metalation step
worked as at 25 ꢀC, affording 2a in 50% yield (entry 4). It is known
that labile ligands can play a role on the course of reactions.9a To
check a possible effect, the reaction was performed at room tem-
perature in the presence of 1 equiv of TMEDA; the 39 and 59%
yields, respectively, obtained with and without TMEDA indicates
the deleterious influence of this ligand, uninteresting in this case
(entry 5). The impact of the reaction time was next considered. It
was observed that reducing the reaction time to 30 min resulted in
The formation of the dimer 3 has been observed in all the ex-
periments where metalation took place, but in various yields. Its
formation does not seem to depend on the deprotonation

8906
G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
Table 2
temperature (entries 1e4), but seems to be favored with long
contact times (entry 8). In addition, it is clear that the use of 2 equiv
of base prevents its formation (entries 11 and 12), as if it formed
intramolecularly. Using water instead of iodine to trap the meta-
lated anisole derivative also resulted in the formation of 3 in
a similar 14% yield (entry 19). Thus, if cross-coupling with the
iodide 2,12c,18 and iodine-mediated oxidation19 can be proposed to
explain the formation of 3, alternative ways without recourse to
them exist. A possible in situ partial reduction of Co(II) species to Co
(I) due to the presence of metal amides is possible,20 but would not
lead to a dimer in the absence of an halide.21 Even if the use of
degassed THF did not change significantly the result (entry 19),22
a possible role of dissolved oxygen cannot be ruled out.19 An al-
ternative explanation could be the presence of a metal impurity in
CoBr2 for which the corresponding diaryl metal ate compounds is
prone to dimerization. Using allyl bromide instead of iodine (or
water) to quench the metalated anisole derivative produced the
dimer 3 in 38% yield, and 2-allylanisole (2b) in 6% yield besides
(Entry 20). One-electron transfers from cobalt(II) ate compounds to
allyl bromide are possible pathways,23 and dimerization from the
generated Co(III) species bearing two aryl groups18a appears as
a possible pathway to explain the formation of 3 in this case
(Scheme 1). Other electrophiles favor the dimerization. For exam-
ple, the use of 2-bromopyridine in order to convert the metalated
anisole into the cross-coupling product 2c was similarly threatened
by a significant formation of 3 (entry 21).
The optimized conditions in hands, the use of different elec-
trophiles was attempted (Table 2). Anisaldehyde led to the corre-
sponding alcohol 2d in a satisfying yield (entry 2). The alcohol 2e
and ketone 2f were produced in moderate yields upon interception
with benzophenone and benzoyl chloride, respectively (entries 3
and 4). The phosphine 2g was obtained satisfactorily using chlor-
odiphenylphosphine, but the cross-coupled derivative 2c was iso-
lated in a low 25% yield due to a significant formation of 3 (entry 6).
The method was then extended to other aromatic substrates
(Table 3). Starting from 1,4-dimethoxybenzene (4) and using io-
dine as electrophile, the expected derivative 5a was obtained in
a correct yield provided that 2 equiv of base were used (entries
1e3). It was noted that a longer reaction time favored the co-
formation of diiodides. Trapping with allyl bromide resulted in
a significant formation of the dimer 6 whereas the expected
allylated compound 5b was isolated in a low 6% yield (entry 4).
These results are similar to those obtained from anisole (1).
Benefiting from a greater activation, 1,3-dimethoxybenzene (7)
was quantitatively converted to the iodide 8a (entry 5). Using allyl
bromide instead of iodine yielded the derivative 8b in a low yield
due to a significant recovery of starting material; in this case, the
corresponding dimer 9 was isolated in a low 6% yield (entry 6).
The behavior of 1,2-dimethoxybenzene (10) is similar to that of
1,4-dimethoxybenzene (4); the formation of the corresponding
dimer 12 was suppressed by reducing the reaction time to 30 min
(entries 7 and 8). Trapping using allyl bromide led to a significant
formation of the dimer 12, limiting the yield of the allylated
derivative 11b to 23% (entry 9). 1,2,3-Trimethoxybenzene (13)
led to the expected iodide 14 in a moderate 33% yield, due to a
Electrophilic trapping of metalated anisole
OMe
OMe
1) CoBr2 (2 equiv)
+ LiTMP (6 equiv)
THF, rt, 30 min
OMe
E
)
2
+
2) Electrophile
(6 equiv)
3) Hydrolysis
1
2
3
Entry
1
Electrophile
I2
2, Yield (%)
Yield of 3 (%)
OMe
2a, 93
I
5
OMe OH
2d ,8 4
2
3
4
5
4-MeOC6H4eCHO
PhC(O)Ph
15
10
16
15
OMe
OMe OH
2e, 45
Ph
Ph
OMe O
2f
PhC(O)Cl
Ph
OMe
2g
PPh2
Ph2PCl
OMe
2c
c
6a
db (33)c
N
Cl
N
a
Trapping step performed at 50 ꢀC instead of rt.
Not quantified.
Using 1 equiv of base.
b
c
significant recovery of starting material (entry 10). Performed
with 2-methoxypyridine (15), the reaction led to a more impor-
tant formation of dimer than starting from methoxybenzenes. The
iodide resulting from a regioselective metalation next to the
methoxy group was isolated in a moderate 43% yield (entries 11
and 12). Except an increased conversion, a similar result was
observed from 2,6-dimethoxypyridine (18) (entry 13). The
method is not suitable to functionalize substrates bearing reactive
functions. Indeed, using ethyl benzoate (21), side reactions with
the ester function only allowed the expected iodide 22 to be
obtained in maximum 22% yield (entries 14 and 15). A depro-
tonative metalation followed by a cross-coupling reaction was
carried out from thiophene. Using 1 equiv of base (in order to
avoid 2,5-dideprotonation),9d the expected cross-coupled com-
pound was isolated, but in a low 19% yield (entry 16).
MeO
MeO
Br
OMe
TMP CoII
MeO
TMP CoIII
MeO
TMPCoI
Li
+
MeO
-
Li+
Br
3
LiBr +
Scheme 1. Possible pathway for the formation of 3 from the metalated anisole derivative.

G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
8907
Table 3
Extension to other aromatic substrates including heterocycles
1) CoBr2 (x equiv)
+ LiTMP (3x equiv)
THF, rt, reaction time
Ar
H
Ar
E
Ar Ar
+
2) Electrophile (3x equiv)
3) Hydrolysis
Entry
1
AreH
4:
x
Reaction time
2 h
Electrophile
I2
AreE (E), yield
5a (I), 10%
AreAr, yield
0.5
6, 22%
H
OMe
2
3
4
1
2
2
2 h
30 min
30 min
I2
I2
5a (I), 45%
5a (I), 76%
5b (CH2CH]CH2), 6%
da
6, 10%
6, 33%
MeO
BrCH2CH]CH2
OMe
5
6
2
2
30 min
30 min
I2
8a (I), 97%
H
7:
BrCH2CH]CH2
8b (CH2CH]CH2), 14%
9, 6%
OMe
H
7
2
2 h
I2
11a (I), 76%
12, 17%
10:
OMe
8
9
2
2
30 min
30 min
I2
11a (I), 74%
11b (CH2CH]CH2), 23%
12, 0%
12, 62%
BrCH2CH]CH2
OMe
H
OMe
OMe
10
13:
2
30 min
I2
14 (I), 33%
OMe
H
11
12
1
2
2 h
2 h
I2
I2
16 (I), 11%
16 (I), 43%
17, 19%
17, 14%
15:
18:
OMe
H
N
13
2
30 min
I2
19 (I), 64%
20, 34%
MeO
OMe
N
da
da
da
H
14
15
1
2
1
2 h
2 h
2 h
I2
22 (I), 14%
21:
I2
22 (I), 22%
CO2Et
H
16b
23:
4-IC6H4OMe
24 (4-C6H4OMe), 19%
S
a
Not quantified.
Using 1 equiv of base.
b
3. Conclusion
In conclusion, compared with the previously reported ‘all-TMP’
reagents, the combination here presented allows more efficient
direct trappings for the generated arylmetal compounds, but lacks
both efficiency and chemoselectivity. Studies are under deve-
lopment to identify more suitable lithiumemetal systems.
Like the other lithiumemetal combinations, the mixture of
CoBr2 and 3 equiv of LiTMP behaves synergically, but compared
with the previously described ‘all-TMP’ lithiumezinc9 and lith-
iumecadmium10 combinations, the base obtained by combining
CoBr2 with 3 equiv of LiTMP is less efficient as far as both conver-
sion and chemoselectivity are concerned. For example, starting
from anisole (1), the iodide 2a was isolated in 84% and 75% yields
using 0.5 equiv of the lithiumezinc and lithiumecadmium com-
binations, respectively, against 59% under the same conditions
using 1 equiv of the lithium-cobalt one. Concerning the metalation
of methoxybenzenes, its efficiency more looks like that of the
reported ‘all-TMP’ Gilman-type lithiumecopper(I) combination.11
Nevertheless, the reactivity exhibited by the generated arylmetal
species has been improved using lithiumecobalt bases.
4. Experimental section
4.1. General procedure A (deprotonation using 2 equiv CoBr2
and 6 equiv LiTMP followed by trapping using I2)
To a stirred cooled (0 ꢀC) solution of 2,2,6,6-tetramethylpiper-
idine (4.1 mL, 24 mmol) in THF (8 mL) were added BuLi (1.6 M
hexanes solution, 24 mmol) and, 5 min later, CoBr2 (1.7 g,
8.0 mmol). The mixture was stirred for 10 min at 0 ꢀC before in-
troduction of the substrate (4.0 mmol). After 2 h at room

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G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
temperature, a solution of I2 (6.1 g, 24 mmol) in THF (7 mL) was
added. The mixture was stirred overnight before addition of an aq
saturated solution of Na2S2O3 (10 mL) and extraction with EtOAc
(3ꢁ20 mL). The combined organic layers were dried over MgSO4,
filtered, and concentrated under reduced pressure.
CDCl3):
d
3.98 (s, 3H), 6.64 (dd, 1H, J¼4.8 and 7.5 Hz), 8.02 (dd, 1H,
J¼1.7 and 7.5 Hz), 8.11 (dd, 1H, 1.7 and 4.8 Hz); 13C NMR (75 MHz,
CDCl3):
d 161.8, 147.9, 146.4, 118.1, 79.7, 54.6.
4.1.8. 2,20-Dimethoxybipyridine (17). Compound 17 was obtained
according to the general procedure A starting from 2-methox-
ypyridine (0.42 mL), but using 2,2,6,6-tetramethylpiperidine
(2.0 mL, 12 mmol), BuLi (12 mmol), and CoBr2 (0.84 g, 4.0 mmol). It
was isolated after purification by flash chromatography on silica gel
(eluent: heptane/AcOEt 98/2) as a light yellow solid (19% yield): mp
4.1.1. 2-Iodoanisole (2a). Compound 2a was obtained according to
the general procedure A starting from anisole (0.44 mL), but re-
ducing the metalation reaction time to 30 min, and was isolated
after purification by flash chromatography on silica gel (eluent:
heptane/CH2Cl2 95/5) as a colorless oil (93% yield). The analyses are
as described previously.10a
104 ꢀC (lit.29 139e140 ꢀC); 1H NMR (300 MHz, CDCl3):
d 3.92 (s, 6H),
6.95 (dd, 2H, J¼5.0 and 7.2 Hz), 7.59 (dd, 2H, J¼1.9 and 7.2 Hz), 8.18
(dd, 2H, J¼1.9 and 5.0 Hz); 13C NMR (75 MHz, CDCl3):
d 161.1 (2C),
4.1.2. 2-Iodo-1,4-dimethoxybenzene (5a). Compound 5a was ob-
tained according to the general procedure A starting from 1,4-
dimethoxybenzene (0.55 g), but reducing the metalation reaction
time to 30 min, and was isolated after purification by flash chro-
matography on silica gel (eluent: heptane/AcOEt 97/3) as a yellow
146.2 (2C), 139.5 (2C), 119.8 (2C), 116.4 (2C), 53.5 (2C).
4.1.9. 3-Iodo-2,6-dimethoxypyridine (19)30. Compound 19 was
obtained according to the general procedure A starting from 2,6-
dimethoxypyridine (0.53 mL), but reducing the metalation reaction
time to 30 min, and was isolated after purification by flash chro-
matography on silica gel (eluent: heptane/AcOEt 98/2) as a brown
solid (76% yield): mp <50 ꢀC; 1H NMR (300 MHz, CDCl3):
d 3.74 (s,
3H), 3.81 (s, 3H), 6.94 (d, 1H, J¼8.9 Hz), 6.85 (dd, 1H, J¼2.9 and
8.9 Hz), 7.33 (d, 1H, J¼2.9 Hz); 13C NMR (75 MHz, CDCl3):
d
154.2,
solid (64% yield): mp <50 ꢀC; 1H NMR (300 MHz, CDCl3):
d 3.88 (s,
152.6, 124.7, 114.6, 111.5, 85.9, 56.9, 55.8. These data are analogous
to those previously described.24
3H), 3.95 (s, 3H), 6.13 (d, 1H, J¼8.2 Hz), 7.78 (d, 1H, J¼8.2 Hz); 13C
NMR (75 MHz, CDCl3):
d
163.2, 160.5, 149.3, 103.4, 65.5, 54.3, 53.5;
ꢂ
HRMS calcd for C7H8INNaO2 [(MþNa)þ ] 287.9497 and C7H9INO2
ꢂ
4.1.3. 2,20,5,50-Tetramethoxybiphenyl (6). Compound 6 was obtained
according to the general procedure A starting from 1,4-dimeth-
oxybenzene (0.55 g), but using 2,2,6,6-tetramethylpiperidine
(1.0 mL, 6.0 mmol), BuLi (6.0 mmol), and CoBr2 (0.42 g, 2.0 mmol). It
was isolated after purification by flash chromatography on silica gel
(eluent: heptane/AcOEt 88/12) as a red solid (22% yield): mp
[(MþH)þ ] 265.9678, found 287.9492 and 265.9680, respectively.
4.1.10. 2,20,6,60-Tetramethoxy-3,30-bipyridine (20)30. Compound 20
was obtained according to the general procedure A starting from
2,6-dimethoxypyridine (0.53 mL), but reducing the metalation re-
action time to 30 min, and was isolated after purification by flash
chromatography on silica gel (eluent: heptane/AcOEt 96/4) as
a white solid (34% yield): mp 144.5 ꢀC; 1H NMR (300 MHz, CDCl3):
94e95 ꢀC; 1H NMR (300 MHz, CDCl3):
d 3.73 (s, 6H), 3.78 (s, 6H),
6.83e6.88 (m, 4H), 6.91 (dd, 2H, J¼1.0 and 8.4 Hz); 13C NMR
(75 MHz, CDCl3):
d
153.3 (2C), 151.1 (2C), 128.6 (2C), 117.1 (2C), 113.4
d
3.92 (s, 6H), 3.94 (s, 6H), 6.36 (d, 2H, J¼8.0 Hz), 7.52 (d, 2H,
(2C), 112.4 (2C), 56.6 (2C), 55.7 (2C). These data are analogous to
J¼8.0 Hz); 13C NMR (75 MHz, CDCl3):
d 162.0 (2C), 159.6 (2C), 142.5
those previously described.25
(2C), 110.5 (2C), 100.4 (2C), 53.4 (2C), 53.3 (2C); HRMS calcd for
ꢂ
ꢂ
C14H16N2NaO4 [(MþNa)þ ] 299.1008 and C14H17N2O4 [(MþH)þ
]
4.1.4. 2-Iodo-1,3-dimethoxybenzene (8a). Compound 8a was ob-
tained according to the general procedure A starting from 1,3-
dimethoxybenzene (0.55 g), but reducing the metalation reaction
time to 30 min, and was isolated after purification by flash chro-
matography on silica gel (eluent: heptane/AcOEt 60/40) as a white
solid (97% yield): mp 106 ꢀC (lit.26 100 ꢀC); 1H NMR (300 MHz,
277.1188, found 299.1007 and 277.1192, respectively.
4.1.11. Ethyl 2-iodobenzoate (22). Compound 22 was obtained
according to the general procedure A starting from ethyl benzoate
(0.61 mL), and was isolated after purification by flash chromatogra-
phy on silica gel (eluent: heptane/AcOEt 98/2) as a yellow oil (22%
CDCl3):
NMR (75 MHz, CDCl3):
d
3.88 (s, 6H), 6.49 (d, 2H, J¼8.2 Hz), 7.25 (t,1H, J¼8.2 Hz); 13
C
yield): 1H NMR (300 MHz, CDCl3):
d
1.41 (t, 3H, J¼7.1 Hz), 4.39 (q, 2H,
d
159.4 (2C),129.7, 104.0 (2C), 77.5, 56.5 (2C).
J¼7.1 Hz), 7.14 (td,1H, J¼1.7 and 7.8 Hz), 7.39 (td, 1H, J¼1.7 and 7.9 Hz),
7.79(dd,1H, J¼1.7 and 7.8 Hz), 7.98 (dd, 1H, J¼1.0 and 7.9 Hz); 13CNMR
4.1.5. 1-Iodo-2,3-dimethoxybenzene (11a). Compound 11a was
obtained according to the general procedure A starting from vera-
trole (0.50 mL), and was isolated after purification by flash chro-
matography on silica gel (eluent: heptane/AcOEt 98/2) as a yellow
solid (76% yield). The analyses are as described previously.10a
(75 MHz, CDCl3): d 166.5, 141.1, 135.4, 132.4, 130.7, 127.8, 93.9, 61.6,
14.1. These data are analogous to those previously described.31
4.2. General procedure B (deprotonation using 2 equiv CoBr2
and 6 equiv LiTMP followed by trapping with an
electrophilesI2)
4.1.6. 1-Iodo-2,3,4-trimethoxybenzene (14). Compound 14 was ob-
tained according to the general procedure A starting from 1,2,3-
trimethoxybenzene (0.68 g), but reducing the metalation reaction
time to 30 min, and was isolated after purification by flash chro-
matography on silica gel (eluent: heptane/CH2Cl2 50/50) as a light
yellow solid (33% yield): mp <50 ꢀC (lit.27 42 ꢀC); 1H NMR
To a stirred cooled (0 ꢀC) solution of 2,2,6,6-tetramethylpiper-
idine (4.1 mL, 24 mmol) in THF (8 mL) were added BuLi (1.6 M
hexanes solution, 24 mmol) and, 5 min later, CoBr2 (1.7 g,
8.0 mmol). The mixture was stirred for 10 min at 0 ꢀC before in-
troduction of the substrate (4.0 mmol). After 30 min at room tem-
perature, the electrophile (24 mmol) was added. The mixture was
stirred overnight before addition of H2O (10 mL) and extraction
with EtOAc (3ꢁ20 mL). The combined organic layers were dried
over MgSO4, filtered, and concentrated under reduced pressure.
(300 MHz, CDCl3):
d 3.84 (s, 3H), 3.86 (s, 3H), 3.87 (s, 3H), 6.49 (d,
1H, J¼8.8 Hz), 7.40 (d, 1H, J¼8.8 Hz); 13C NMR (75 MHz, CDCl3):
d
154.3, 153.3, 142.6, 132.5, 109.7, 81.2, 60.9, 60.8, 56.1.
4.1.7. 3-Iodo-2-methoxypyridine (16). Compound 16 was obtained
according to the general procedure A starting from 2-methox-
ypyridine (0.42 mL), and was isolated after purification by flash
chromatography on silica gel (eluent: heptane/Et2O 85/15) as
a white solid (43% yield): mp 64 ꢀC (lit.28 66 ꢀC); 1H NMR (300 MHz,
4.2.1. 2-Allylanisole (2b). Compound 2b was obtained according to
the general procedure B (in this case, an extended reaction time of
2 h was used, and the following amounts for 2,2,6,6-tetrame-
thylpiperidine (2.0 mL, 12 mmol), BuLi (12 mmol), and CoBr2

G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
8909
(0.84 g, 4.0 mmol) were used) starting from anisole (0.44 mL), and
using allyl bromide (1.0 mL, 12 mmol). Compound 2b was isolated
after purification by flash chromatography on silica gel (eluent:
heptane/CH2Cl2 92/8) as a colorless oil (6% yield). The analyses are
as described previously.10e
chromatography on silica gel (eluent: heptane/AcOEt 90/10) as
a yellow oil (25% yield). The analyses are as described previously.9d
4.2.8. 2-Allyl-1,4-dimethoxybenzene (5b). Compound 5b was ob-
tained according to the general procedure B starting from 1,4-dime-
thoxybenzene (0.55 g), and using allyl bromide (2.1 mL). It was
isolated after purification by flash chromatography on silica gel
(eluent: heptane/EtOAc 98/2) as a colorless oil (6% yield): 1H NMR
4.2.2. 2,20-Dimethoxybiphenyl (3). Compound 3 was obtained acc-
ording to the general procedure B (in this case, an extended
reaction time of 2 h was used, and the following amounts for
2,2,6,6-tetramethylpiperidine (2.0 mL, 12 mmol), BuLi (12 mmol)
and CoBr2 (0.84 g, 4.0 mmol) were used) starting from anisole
(0.44 mL), and using allyl bromide (1.0 mL, 12 mmol). Compound 3
was isolated after purification by flash chromatography on silica gel
(eluent: heptane/CH2Cl2 50/50) as a white solid (38% yield): mp
(300 MHz, CDCl3):
d
3.36 (d, 2H, J¼6.6 Hz), 3.76 (s, 3H), 3.78 (s, 3H),
5.01e5.14 (m, 2H), 6.10e5.90 (m, 1H), 6.92e6.68 (m, 3H); 13C NMR
(75 MHz, CDCl3):
d 153.5, 151.5, 136.7, 129.8, 116.1, 115.5, 111.4, 111.3,
56.0, 55.6, 34.2. The 1H NMR data are analogous to those described.36
4.2.9. 2-Allyl-1,3-dimethoxybenzene (8b)37. Compound 8b was ob-
tained according to the general procedure B starting from 1,3-
dimethoxybenzene (0.55 g), and using allyl bromide (2.1 mL). It was
isolated after purification by flash chromatography on silica gel
(eluent: heptane/CH2Cl2 90/10) as a colorless oil (14% yield): 1H NMR
158e160 ꢀC; 1H NMR (300 MHz, CDCl3):
(m, 4H), 7.28 (dd, 2H, J¼1.7 and 7.4 Hz), 7.36 (td, 2H, J¼1.7 and
8.2 Hz); 13C NMR (75 MHz, CDCl3):
156.9 (2C), 131.4 (2C), 128.5
d 3.80 (s, 6H), 7.07e6.99
d
(2C), 127.7 (2C), 120.2 (2C), 111.0 (2C), 55.6 (2C). These data are
analogous to those previously described.32
(300 MHz, CDCl3):
d
3.42 (dt, 2H, J¼1.5 and 6.1 Hz), 3.81 (s, 6H),
4.90e5.00 (m, 2H), 5.89e6.02 (m, 1H), 6.56 (d, 2H, J¼8.3 Hz), 7.14 (t,
1H, J¼8.3 Hz); 13C NMR (75 MHz, CDCl3):
d 158.2 (2C), 136.8, 127.0,
4.2.3. (2-Methoxyphenyl)(4-methoxyphenyl)methanol (2d). Com-
pound 2d was obtained according to the general procedure B
starting from anisole (0.44 mL), and using anisaldehyde (3.0 mL). It
was isolated after purification by flash chromatography on silica gel
(eluent: heptane/CH2Cl2 40/60) as a light yellow oil (84% yield). The
analyses are as described previously.9d
116.5, 113.9, 103.8 (2C), 55.8 (2C), 27.1.
4.2.10. 2,20,6,60-Tetramethoxybiphenyl (9). Compound 9 was ob-
tained according to the general procedure B starting from 1,3-
dimethoxybenzene (0.55 g), and using allyl bromide (2.1 mL). It
was isolated after purification by flash chromatography on silica gel
(eluent: heptane/CH2Cl2 30/70) as a white solid (6% yield): mp
4.2.4. (2-Methoxyphenyl)diphenylmethanol (2e). Compound 2e was
obtained according to the general procedure B starting from anisole
(0.44 mL), and using benzophenone (4.4 g). It was isolated after
purification by flash chromatography on silica gel (eluent: heptane/
Et2O 90/10) as a white solid (45% yield): mp 114.5 ꢀC (lit.33
176 ꢀC (lit.37 174e175 ꢀC); 1H NMR (300 MHz, CDCl3):
d 3.72 (s,
12H), 6.65 (d, 4H, J¼8.3 Hz), 7.29 (t, 2H, J¼8.3 Hz); 13C NMR
(75 MHz, CDCl3): d 158.3 (4C), 128.6 (2C), 112.5 (2C), 104.4 (4C), 56.1
(4C). These data are analogous to those previously described.38
111e113 ꢀC); 1H NMR (300 MHz, CDCl3):
d
3.81 (s, 3H), 7.08e7.01
(m, 2H), 7.40e7.18 (m, 7H), 7.66e7.49 (m, 3H), 7.83e7.87 (m, 2H),
OH not seen; 13C NMR (75 MHz, CDCl3):
156.9, 144.1, 131.3, 128.5
4.2.11. 1-Allyl-2,3-dimethoxybenzene (11b)39. Compound 11b was
obtained according to the general procedure B starting from vera-
trole (0.50 mL), and using allyl bromide (2.1 mL). It was isolated
after purification by flash chromatography on silica gel (eluent:
heptane/AcOEt 98/2) as a colorless oil (23% yield): 1H NMR
d
(4C), 128.5, 127.7, 127.1 (4C), 126.8, 120.2, 110.9, 82.9, 55.5.
4.2.5. 2-Methoxybenzophenone (2f). Compound 2f was obtained
(300 MHz, CDCl3):
d
3.42 (d, 2H, J¼6.5 Hz), 3.81 (s, 3H), 3.86 (s, 3H),
according to the general procedure
B starting from anisole
5.02e5.10 (m, 2H), 5.91e6.05 (m, 1H), 6.76e6.81 (m, 2H), 7.00 (t,
(0.44 mL), and using benzoyl chloride (2.8 mL). It was isolated after
purification by flash chromatography on silica gel (eluent: heptane/
CH2Cl2 50/50) as a white solid (30% yield): mp <50 ꢀC (lit.34
1H, J¼7.8 Hz); 13C NMR (75 MHz, CDCl3):
d 152.7, 147.0, 137.2, 133.9,
123.8, 121.9, 115.4, 110.4, 60.5, 55.6, 33.9.
35e37 ꢀC); 1H NMR (300 MHz, CDCl3):
d
3.72 (s, 3H), 6.98e7.07
(m, 2H), 7.34e7.58 (m, 5H), 7.79e7.83 (m, 2H); 13C NMR (75 MHz,
CDCl3): 196.4, 157.3, 137.7, 132.9, 131.8, 129.8 (2C), 129.5, 128.8,
4.2.12. 2,20,3,30-Tetramethoxybiphenyl (12). Compound 12 was ob-
tained according to the general procedure B starting from veratrole
(0.50 mL), and using allyl bromide (2.1 mL). It was isolated after pu-
rification by flash chromatography on silica gel (eluent: heptane/
AcOEt 88/12) as a white solid (62% yield): mp 106e108 ꢀC (lit.40
d
128.1 (2C), 120.4, 111.4, 55.5.
104e105 ꢀC); 1H NMR (300 MHz, CDCl3):
d 3.65 (s, 6H), 3.90 (s, 6H),
4.2.6. (2-Methoxyphenyl)diphenylphosphine (2g). Compound 2g
was obtained according to the general procedure B starting from
anisole (0.44 mL), and using chlorodiphenylphosphine (4.3 mL). Due
to its suspected easy oxidation, all the solvents were degassed before
use. It was isolated after purification by flash chromatography on
silica gel (eluent: heptane/CH2Cl2 85/15) as a white solid (82% yield):
6.87 (dd, 2H, J¼1.6 and 7.6 Hz), 6.93 (dd, 2H, J¼1.6 and 8.2 Hz), 7.08
(dd, 2H, J¼7.6 and 8.2 Hz); 13C NMR (75 MHz, CDCl3):
d 152.7 (2C),
146.7 (2C),132.8 (2C),123.2 (2C),123.2 (2C),111.5 (2C), 60.5 (2C), 55.7
ꢂ
(2C); HRMS calcd for C16H18NaO4 [(MþNa)þ ] 297.1103 and C16H18KO4
ꢂ
[(MþK)þ ] 313.0842, found 297.1104 and 313.0854, respectively.
mp 123 ꢀC (lit.35 118 ꢀC); 1H NMR (300 MHz, CDCl3):
6.69e6.73 (m, 1H), 6.86e6.95 (m, 2H), 7.28e7.39 (m, 11H); 13C NMR
(75 MHz, CDCl3):
d 3.76 (s, 3H),
4.2.13. 2-(4-Methoxyphenyl)thiophene (24). Compound 24 was
obtained according to the general procedure B starting from thio-
phene (0.32 g), but using 2,2,6,6-tetramethylpiperidine (2.0 mL,
12 mmol), BuLi (12 mmol), and CoBr2 (0.84 g, 4.0 mmol). It was
isolated after purification by flash chromatography on silica gel
(eluent: heptane) as a yellow solid (19% yield). The analyses are as
described previously.10e
d
161.0 (d, JP¼15 Hz), 136.6 (d, 2C, JP¼10 Hz), 133.8
(d, 4C, JP¼20 Hz), 133.5 (d, JP¼0.7 Hz), 130.2, 128.4 (2C), 128.3 (d, 4C,
JP¼12 Hz), 125.5 (d, JP¼12 Hz), 120.9 (d, JP¼0.8 Hz), 110.1 (d,
JP¼1.7 Hz), 55.5 (d, JP¼0.7); 31P NMR (75 MHz, CDCl3):
d
ꢃ16.8;
ꢂ
HRMS calcd for C19H17NaOP [(MþNa)þ ] 315.0915 and C19H18OP
ꢂ
[(MþH)þ ] 293.1095, found 315.0913 and 293.1094, respectively.
4.2.7. 2-(2-Methoxyphenyl)pyridine (2c). Compound 2c was
obtained according to the general procedure B, but performing the
trapping step at 50 ꢀC, starting from anisole (0.44 mL), and using
2-chloropyridine (2.3 mL). It was isolated after purification by flash
Acknowledgements
The authors gratefully acknowledge the financial support of
Agence Nationale de la Recherche (ACTIVATE program) (to G.D.).

8910
G. Dayaker et al. / Tetrahedron 66 (2010) 8904e8910
nomet. Chem. 1975, 99, C19eC20; (c) Kauffmann, T. Angew. Chem., Int. Ed. 1996,
35, 386e403.
13. Ohmiya, H.; Yorimitsu, H.; Oshima, K. Angew. Chem., Int. Ed. 2005, 44,
3488e3490.
They thank Rennes Métropole and the Institut Universitaire
de France.
14. Au-Yeung, H. Y.; Lam, C. H.; Lam, C.-K.; Wong, W.-Y.; Lee, H. K. Inorg. Chem. 2007,
46, 7695e7697.
References and notes
15. Sacconi, L.; Bertini, I.; Mani, F. Inorg. Chem. 1967, 6, 262e267.
16. CoBr2, more soluble than CoCl2, was chosen to replace CoCl2$TMEDA.
17. Uchiyama, M.; Kameda, M.; Mishima, O.; Yokoyama, N.; Koike, M.; Kondo, Y.;
Sakamoto, T. J. Am. Chem. Soc. 1998, 120, 4934e4946.
18. (a) Gosmini, C.; Begouin, J.-M.; Moncomble, A. Chem. Commun. 2008,
3221e3233; (b) Hess, W.; Treutwein, J.; Hilt, G. Synthesis 2008, 3537e3562.
19. (a) Mayer, M.; Czaplik, W. M.; Jacobi von Wangelin, A. Synlett 2009, 2931e2934;
(b) Chen, S.-Y.; Zhang, J.; Li, Y.-H.; Wen, J.; Bian, S.-Q.; Yu, X.-Q. Tetrahedron Lett.
2009, 50, 6795e6797.
1. (a) Gschwend, H. W.; Rodriguez, H. R. Org. React. 1979, 26, 1e360; (b) Beak, P.;
Snieckus, V. Acc. Chem. Res. 1982, 15, 306e312; (c) Snieckus, V. Chem. Rev. 1990,
90, 879e933; (d) Gant, T. G.; Meyers, A. I. Tetrahedron 1994, 50, 2297e2360; (e)
Schlosser, M. In Organometallics in Synthesis, 2nd ed.; Schlosser, M., Ed.; Wiley:
Lausanne, Switzerland, 2002, Chapter I.
2. Schlosser, M. Pure Appl. Chem. 1988, 60, 1627e1634.
3. Lochmann, L. Eur. J. Inorg. Chem. 2000, 7, 1115e1126.
4. Gros, P. C.; Fort, Y. Eur. J. Org. Chem. 2009, 4199e4209 and references cited
therein.
20. Scott, J.; Gambarotta, S.; Korobkov, I. Can. J. Chem. 2005, 83, 279e285.
21. The use of Zn as reductant did not change the yield of 3 either.
22. The use of nitrobenzene or chloranil did not change the yield of 3 either.
23. (a) Wakabayashi, K.; Yorimitsu, H.; Oshima, K. J. Am. Chem. Soc. 2001, 123,
5374e5375; (b) Affo, W.; Ohmiya, H.; Fujioka, T.; Ikeda, Y.; Nakamura, T.; Yor-
imitsu, H.; Oshima, K.; Imamura, Y.; Mizuta, T.; Miyoshi, K. J. Am. Chem. Soc.
2006, 128, 8068e8077.
5. (a) Mulvey, R. E. Organometallics 2006, 25, 1060e1075; (b) Mulvey, R. E.;
Mongin, F.; Uchiyama, M.; Kondo, Y. Angew. Chem., Int. Ed. 2007, 46,
3802e3824; (c) Mulvey, R. E. Acc. Chem. Res. 2009, 42, 743e755.
6. (a) Clegg, W.; Dale, S. H.; Drummond, A. M.; Hevia, E.; Honeyman, G. W.;
Mulvey, R. E. J. Am. Chem. Soc. 2006, 128, 7434e7435; (b) Clegg, W.; Conway, B.;
Hevia, E.; McCall, M. D.; Russo, L.; Mulvey, R. E. J. Am. Chem. Soc. 2009, 131,
2375e2384.
7. Alborés, P.; Carrella, L. M.; Clegg, W.; García-Álvarez, P.; Kennedy, A. R.; Klett, J.;
Mulvey, R. E.; Rentschler, E.; Russo, L. Angew. Chem., Int. Ed. 2009, 48, 3317e3321.
8. Wunderlich, S. H.; Knochel, P. Angew. Chem., Int. Ed. 2009, 48, 9717e9720.
9. (a) Seggio, A.; Lannou, M. I.; Chevallier, F.; Nobuto, D.; Uchiyama, M.; Golhen, S.;
Roisnel, T.; Mongin, F. Chem.dEur. J. 2007, 13, 9982e9989; (b) Seggio, A.;
Chevallier, F.; Vaultier, M.; Mongin, F. J. Org. Chem. 2007, 72, 6602e6605; (c)
L’Helgoual’ch, J. M.; Seggio, A.; Chevallier, F.; Yonehara, M.; Jeanneau, E.;
Uchiyama, M.; Mongin, F. J. Org. Chem. 2008, 73, 177e183; (d) Snégaroff, K.;
Komagawa, S.; Chevallier, F.; Gros, P. C.; Golhen, S.; Roisnel, T.; Uchiyama, M.;
Mongin, F. Chem.dEur. J. 2010, 16, 8191e8201.
10. (a) L’Helgoual’ch, J. M.; Bentabed-Ababsa, G.; Chevallier, F.; Yonehara, M.;
Uchiyama, M.; Derdour, A.; Mongin, F. Chem. Commun. 2008, 5375e5377; (b)
L’Helgoual’ch, J. M.; Bentabed-Ababsa, G.; Chevallier, F.; Derdour, A.; Mongin, F.
Synthesis 2008, 4033e4035; (c) Bentabed-Ababsa, G.; Blanco, F.; Derdour, A.;
Mongin, F.; Trécourt, F.; Queguiner, G.; Ballesteros, R.; Abarca, B. J. Org. Chem.
2009, 74, 163e169; (d) Snégaroff, K.; Lassagne, F.; Bentabed-Ababsa, G.; Nassar,
E.; Cheikh Sid Ely, S.; Hesse, S.; Perspicace, E.; Derdour, A.; Mongin, F. Org.
Biomol. Chem. 2009, 7, 4782e4788; (e) Snégaroff, K.; L’Helgoual’ch, J. M.; Ben-
tabed-Ababsa, G.; Nguyen, T. T.; Chevallier, F.; Yonehara, M.; Uchiyama, M.;
Derdour, A.; Mongin, F. Chem.dEur. J. 2009, 15, 10280e10290; (f) Bentabed-
Ababsa, G.; Cheikh Sid Ely, S.; Hesse, S.; Nassar, E.; Chevallier, F.; Nguyen, T. T.;
Derdour, A.; Mongin, F. J. Org. Chem. 2010, 75, 839e847; (g) Snégaroff, K.;
Komagawa, S.; Yonehara, M.; Chevallier, F.; Gros, P. C.; Uchiyama, M.; Mongin, F.
J. Org. Chem. 2010, 75, 3117e3120.
24. Yamaguchi, Y.; Matsubara, Y.; Ochi, T.; Wakamiya, T.; Yoshida, Z.-i J. Am. Chem.
Soc. 2008, 130, 13867e13869.
25. Kania-Korwel, I.; Parkin, S.; Robertson, L. W.; Lehmler, H.-J. Chemosphere 2004,
56, 735e744.
26. Uchiyama, M.; Naka, H.; Matsumoto, Y.; Ohwada, T. J. Am. Chem. Soc. 2004, 126,
10526e10527.
27. Wirth, H. O.; Konigstein, O.; Kern, W. Justus Liebigs Ann. Chem. 1960, 634,
84e104.
28. Naka, H.; Uchiyama, M.; Matsumoto, Y.; Wheatley, A. E. H.; McPartlin, M.;
Morey, J. V.; Kondo, Y. J. Am. Chem. Soc. 2007, 129, 1921e1930.
29. Tiecco, M.; Testaferri, L.; Tingoli, M.; Chianelli, D.; Montanucci, M. Synthesis
1984, 736e738.
30. Marcuccio, S. M.; Rodopoulos, M.; Weingold, H. WO 98-AU245 9845265, 1998.
31. Zhdankin, V. V.; Koposov, A. Y.; Litvinov, D. N.; Ferguson, M. J.; McDonald, R.;
Luu, T.; Tykwinski, R. R. J. Org. Chem. 2005, 70, 6484e6491.
ꢀ
ꢀ
ꢀ
ꢀ
32. Cepanec, I.; Litvic, M.; Udikovic, J.; Pogorelic, I.; Lovric, M. Tetrahedron 2007, 63,
5614e5621.
33. Chen, Q.; Huang, J. Polym. Int. 2006, 55, 19e24.
34. Elderfield, R. C.; King, T. P. J. Am. Chem. Soc. 1954, 76, 5439e5445.
35. Horner, L.; Simons, G. Phosphorus Sulfur Relat. Elem. 1983, 14, 189e209.
36. Ochiai, M.; Fujita, E.; Arimoto, M.; Yamaguchi, H. Chem. Pharm. Bull. 1982, 30,
3994e3999.
37. Kaliakoudas, D.; Eugster, C. H.; Ruedi, P. Helv. Chim. Acta 1990, 73, 48e62.
38. Govender, S.; Mmutlane, E. M.; van Otterlo, W. A. L.; de Koning, C. B. Org.
Biomol. Chem. 2007, 5, 2433e2440.
39. Kikuchi, Y.; Hasegawa, Y.; Matsumoto, M. Tetrahedron Lett. 1982, 23,
2199e2202.
40. Gilman, H.; Swiss, J.; Cheney, L. C. J. Am. Chem. Soc. 1940, 62, 1963e1967.
11. Nguyen, T. T.; Chevallier, F.; Jouikov, V.; Mongin, F. Tetrahedron Lett. 2009, 50,
6787e6790.
12. (a) Corey, E. J.; Posner, G. H. Tetrahedron Lett. 1970, 11, 315e318; (b) Andersen,
R. A.; Carmona-Guzman, E.; Mertis, K.; Sigurdson, E.; Wilkinson, G. J. J. Orga-