HOTf-catalyzed rearrangement of methylenecyclopropane aryl and alkyl alcohols

Article abstract of DOI:10.1002/ejoc.201000509

An efficient method to synthesize multisubstituted naphthalene and cyclobutanol derivatives through ring opening/ ring enlargement of readily available methylenecyclopropane diaryl alcohols or dialkyl- and monoalkyl- as well as monoaryl alcohols in modera

Full text of DOI:10.1002/ejoc.201000509

FULL PAPER
DOI: 10.1002/ejoc.201000509
HOTf-Catalyzed Rearrangement of Methylenecyclopropane Aryl and Alkyl
Alcohols
Xiang-Ying Tang[a] and Min Shi*[a]
Keywords: Small ring systems / Alcohols / Ring expansion / Aromaticity
An efficient method to synthesize multisubstituted naphth-
alene and cyclobutanol derivatives through ring opening/
ring enlargement of readily available methylenecyclopro-
pane diaryl alcohols or dialkyl- and monoalkyl- as well as
monoaryl alcohols in moderate to good yields has been de-
scribed in this paper. The formation of naphthalene deriva-
tives is a sequential reaction involving a cation-induced ring
opening of cyclopropane, a Friedel–Crafts alkylation reac-
tion, followed by aromatization. On the other hand, the pro-
duction of cyclobutanol derivatives is a cation-induced ring-
enlargement process. The scope and limitations have also
been presented.
reaction outcome of MCP diaryl alcohols 1 or dialkyl- and
monoalkyl- as well as monoaryl alcohols 3 using a variety
of Lewis acids or Brønsted acids, to our delight, it was
found that a set of multisubstituted naphthalenes 2 and cy-
clobutanols 4 could be obtained in moderate to good yields
rather than benzofulvenes. Herein, we wish to report the
full details of this novel ring-opening/ring-expansion re-
arrangement of MCP diaryl alcohols 1 or dialkyl- and
monoalkyl- as well as monoaryl alcohols 3 catalyzed by
Lewis/Brønsted acid under mild conditions.
Introduction
Methylenecyclopropanes (MCPs) are generally utilized
as building blocks in organic synthesis for their ready ac-
cessibility as well as diverse reactivity driven by the relief
of ring strain.[1] The ring-opening reactions of MCPs are
synthetically useful protocols in the construction of com-
plex product structures that have been studied extensively
thus far.[2] For example, during the last 10 years, Lewis/
Brønsted acids and transition-metal-catalyzed reactions in-
volving ring opening of MCPs to form a variety of novel
carbocycles and heterocycles have been extensively investi-
gated.[3,4] Previously, we reported a very interesting silver-
and gold-catalyzed rearrangement of propargylic alcohols
tethered with MCPs for the stereoselective synthesis of al-
lenylcyclobutanols and 1-vinyl-3-oxabicyclo[3.2.1]octan-8-
one derivatives in moderate to good yields under mild con-
ditions.[5] Such a transformation involves a cation-induced
ring-opening rearrangement of cyclopropane to produce an
oxygen-atom-containing heterocyclic ring. Moreover, re-
cently, Gandon and co-workers disclosed a general method
for the preparation of benzofulvenes from diaryl α-hy-
droxyallenes through Nazarov-type cyclizations in the pres-
ence of silver and Brønsted acids (Scheme 1).[6] On the basis
of these findings, we envisaged that an adjacent in situ
formed similar cationic intermediate might induce ring-
opening rearrangement of the cyclopropane to give interest-
ing products (Scheme 1). Therefore, we synthesized a vari-
ety of MCP aryl alcohols or alkyl alcohols to examine such
a rearrangement. During our ongoing investigation on the
Scheme 1. The comparison between allene and MCP.
Results and Discussion
We initially utilized MCP diphenyl alcohol 1a as the sub-
strate to investigate its reaction outcome in dichlorometh-
ane (DCM) at room temperature (20 °C) in the presence
of 10 mol-% of Brønsted acid trifluoromethanesulfonic acid
(CF3SO3H, HOTf; as for the synthesis of 1a, see the Sup-
porting Information). It was found that treatment of 1a for
1.0 h delivered the corresponding naphthalene 2a as a white
solid in 75% yield after usual workup and purification by
column chromatography on silica gel (Table 1, Entry 1).[7]
[a] State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032 China
Fax: +86-21-64166128
E-mail: Mshi@mail.sioc.ac.cn
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201000509.
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HOTf-Catalyzed Rearrangement of MCP Aryl and Alkyl Alcohols
The use of AgOTf and Yb(OTf)3 as the catalysts did not Table 2. Solvent effect of the reaction.
promote this reaction after 24 h, perhaps because both of
these two Lewis acids do not have enough acidity to initiate
the cationic intermediate in this reaction. We found that
BF3·Et2O performed very well in this reaction, affording 2a
in 50% yield within 10 min (Table 1, Entry 4). Other Lewis
acids such as TMSOTf and Fe(OTf)2·2MeCN and the
Brønsted acid CF3CO2H were also suitable catalysts in this
reaction, giving 2a in 40–69% yields within 1.0–10.0 h
(Table 1, Entries 5–8). Conducting the reaction at 0 °C with
the use of HOTf and BF3·Et2O as the catalysts produced
the corresponding naphthalene derivative 2a in 80 and 51%
yield, respectively (Table 1, Entries 9 and 10).
[a] Isolated yield.
Table 1. Optimization of the reaction conditions.
the corresponding naphthalene derivatives 2b, 2d, and 2e
as well as 2c, 2g, and 2h were obtained in 66–86% yield,
respectively, suggesting that the electronic properties of the
aromatic R1 groups have little impact on the outcome of
the reaction (Table 3, Entries 1, 3, 5 and 2, 7, 8). However,
by introducing three strongly electron-donating MeO
groups on the benzene ring of R1 (substrate 1e), the reac-
tion became disordered and a complex mixture was ob-
tained (Table 3, Entry 4). Notably, the same product 2a was
obtained in 74% yield by using Z-1a as the substrate under
identical conditions (Table 3, Entry 6). On the other hand,
in the case of 1i, in which R2 is a para-methyl-substituted
aromatic group, the reaction also proceeded smoothly, giv-
ing the corresponding naphthalene derivative 2i in 87%
yield (Table 3, Entry 9). The preparation of aliphatic sub-
strate 1j (R1 = C7H15) was not successful. It was found that
during the preparation of MCP dialkyl alcohol 1j, a com-
plex mixture was formed (see the Supporting Information).
[a] Isolated yield. [b] The reaction was carried out at 0 °C.
Next, we attempted to investigate the solvent effect of
this reaction in the presence of HOTf (10 mol-%) at 0 °C.
The results of these experiments are summarized in Table 2.
Using 1,2-dichloroethane (DCE) and toluene as the sol-
vents, it was found that 2a was obtained in 88 and 85%
yield within 3 h, respectively (Table 2, Entries 1 and 2). In
other oxygen- or nitrogen-atom-containing solvents such as
THF or MeCN, the reaction became sluggish, yielding 2a
in 20 and 30% yield under identical conditions, respectively
(Table 2, Entries 3 and 4). Moreover, the use of a protogenic
solvent such as MeOH in this reaction turned out to be
unsuccessful, probably because the H+ species was com-
pletely deactivated by MeOH, as the oxygen atom in MeOH
can coordinate to Brønsted acids such as HOTf (Table 2,
Entry 5).
Table 3. HOTf-catalyzed rearrangement of MCP diaryl alcohols
having two identical aromatic groups at the C-1 position.
Having established these optimized reaction conditions,
we next attempted to examine the scope and limitations of
this reaction by using a variety of other MCP diaryl
alcohols having two identical aromatic groups (R2) at the
C-1 position. The results are outlined in Table 3. As for
substrates 1b, 1d, and 1f having electron-donating group
substituted aromatic rings (R1) and 1c, 1g, and 1h bearing
[a] Isolated yield. [b] The preparation of aliphatic substrate 1j was
electron-withdrawing group substituted aromatic rings (R1), failed.
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X.-Y. Tang, M. Shi
FULL PAPER
In the case of MCP diaryl alcohol 1k having two dif-
Interestingly, as for MCP dimethyl alcohol 3a, the ring
ferent aromatic groups at the C-1 position, the correspond- enlargement takes place to give the corresponding cyclobut-
ing naphthalene derivative was obtained as a mixture of anol derivative 4a along with ether derivative 4aЈ (a pair of
isomers 2k and 2kЈ (1:2) in 71% total yield under the stan- diastereoisomers) in 85% total yield rather than the
dard conditions (Scheme 2).
naphthalene derivative under identical conditions (Table 4,
Entry 1). To obtain cyclobutanol derivative 4a as a sole
product, we subsequently optimized the reaction condi-
tions, and the results of these experiments are summarized
in Table 4. It was found that a similar result was obtained
if BF3·OEt2 (10 mol-%) was used as the catalyst (Table 4,
Entry 2), and the Brønsted acid TFA (CF3CO2H) afforded
4a and 4aЈ in 53% total yield (Table 4, Entry 3). Adding
H2O (2.0 equiv.) to the reaction mixture did not suppress
the formation of 4aЈ, giving 4a and 4aЈ in 86% total yield
with a ratio of 1.4:1 (Table 4, Entry 5). Examination of sol-
Scheme 2. MCP diaryl alcohol 1k having two different aromatic vent effects revealed that 4a could be obtained as the major
groups at the C-1 position.
product (4a/4aЈ = 6:1) if MeNO2 was used as the solvent in
the presence of HOTf (Table 4, Entry 6). We carried out the
The two aromatic rings in starting materials 1 are essen-
tial in this reaction to produce naphthalene derivatives in
good yields because the use of MCP monoaryl alcohol 1l
(a pair of diastereoisomers) as the substrate gave a complex
mixture under the standard conditions, presumably because
the in situ generated cationic intermediate derived from the
MCP monoaryl alcohol is not very stable for the next reac-
tion, such as an intramolecular Friedel–Crafts reaction (see
the plausible mechanism, Scheme 3).
reaction at a lower concentration of MeNO2 (0.05 , and it
was found that the yield of 4a was 70%, which is almost
same as that obtained at a concentration of 0.1  (Table 4,
Entry 6). Under these optimized conditions, the substrate
scope was also examined, and the results are outlined in
Table 5. The corresponding cyclobutanols 4a–l were ob-
tained in 38–72% yield along with trace amounts of ether
byproducts (Table 5, Entries 1–6 and 8–13). As for sub-
strates 3d and 3g having electron-donating substituents at
the para position of the benzene rings, the corresponding
products were attained in moderate yields (Table 5, En-
tries 4 and 8). Using MCP monoaryl alcohols 3h and 3i as
well as MCP monoalkyl alcohols 3j and 3k as the sub-
strates, the reaction also proceeded smoothly to give the
corresponding products 4h and 4i as well as 4j and 4k in
good yields with anti configuration under the standard con-
ditions, presumably due to steric effects (Table 5, Entries 9–
12).[8] Only in the case of Z-MCP dimethyl alcohol 3a was
a complex mixture formed, presumably also due to steric
effects in the alkyl migration (Table 5, Entry 7).
Scheme 3. Reaction of MCP monoaryl alcohol 1l under the stan-
dard conditions.
A plausible reaction mechanism for this ring-opening re-
arrangement is shown in Scheme 4 by using 1a as a model.
The in situ generated cationic intermediate A undergoes
ring-opening to give intermediate B, which produces inter-
mediate C through allylic rearrangement. The intramolecu-
lar Friedel–Crafts reaction affords intermediate D, which
undergoes aromatization to give naphthalene 2a.
Table 4. Optimization of the reaction conditions of MCP dimethyl
alcohol 3a.
Scheme 4. A plausible reaction mechanism.
[a] Isolated yield. [b] 2.0 equiv. of H2O was added.
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HOTf-Catalyzed Rearrangement of MCP Aryl and Alkyl Alcohols
Table 5. Ring-opening reaction of various MCP alkyl alcohols.
Comparing the formation of 2 and 4 in Schemes 4 and
5, we thought that steric effects played an important role in
the manner in which bond cleavage occurred in the MCP
alcohols. MCP diaryl alcohols preferred to undergo a ring-
opening process to release ring strain, whereas the MCP
monoaryl alcohols and dialkyl alcohols tended to undergo
cation-induced ring enlargement.
Conclusions
We have found a novel ring-opening/ring-expansion re-
arrangement of MCP diaryl alcohols 1 or dialkyl- and
monoalkyl- as well as monoaryl alcohols 3 catalyzed by the
Brønsted acid HOTf under mild conditions, affording inter-
esting multisubstituted naphthalene derivatives 2 and cyclo-
butanol derivatives 4 in moderate to good yields. In ad-
dition, in the reactions of MCP monoaryl alcohols 3h and
3i, none of the naphthalene products was observed. The
plausible reaction mechanisms have been discussed and the
wide substrate scope has been indicated. The potential utili-
zation of the products and the extension of the scope of the
methodology are currently under investigation.
[a] Isolated yield. [b] The product was obtained exclusively with the
anti configuration.
Experimental Section
A plausible reaction mechanism for this intramolecular
ring enlargement is shown in Scheme 5 by using 3a as a
model. In situ generated cationic intermediate E undergoes
ring enlargement to give intermediate F, which produces 4a
through reaction with water. The reaction of intermediate
F with 4a affords byproduct 4aЈ. It should be noted that
both the transformations of F into 4a and F into 4aЈ are
reversible in the presence of H+, and when a strong polar
solvent (MeNO2) is used, H+ can react with F more easily
than 4a, giving 4a as the major product.
General Procedure for the Rearrangement of MCP Aryl and Alkyl
Alcohols: A Schlenk tube was charged with MCP aryl alcohol 1a
(0.2 mmol, 62.4 mg) in DCE (2.0 mL) or MCP alkyl alcohol 3a
(0.2 mmol, 39.6 mg) in CH3NO2 (2.0 mL). The mixture was cooled
to 0 °C (room temp. for CH3NO2), and then HOTf (3.0 mg,
10 mol-%) was added by syringe. The reaction was stirred at 0 °C
for 3 h. The solvent was removed under reduced pressure, and then
the residue was purified by a flash column chromatography.
Compound 2a: Yield: 34 mg, 88%. This is a known compound.[7]
1H NMR (300 MHz, CDCl3, TMS): δ = 2.26 (s, 3 H, CH3), 7.31–
7.35 (m, 4 H, Ar), 7.38 (s, 1 H, Ar), 7.41–7.57 (m, 9 H, Ar), 7.89–
7.92 (m, 1 H, Ar) ppm. 13C NMR (75 MHz, CDCl3, TMS): δ =
20.8, 124.8, 125.6, 125.8, 126.5, 127.0, 127.2, 128.2, 128.4, 129.7,
130.0, 130.1, 130.2, 132.6, 133.2, 137.8, 139.4, 139.8, 140.8 ppm.
Compound 4a: Yield: 22 mg, 63%. Colorless oil. 1H NMR
(400 MHz, CDCl3, TMS): δ = 1.23 (s, 6 H, 2CH3), 1.78 (d, J =
6.8 Hz, 1 H, OH), 2.91–2.97 (m, 1 H), 3.31–3.37 (m, 1 H), 4.05–
4.10 (m, 1 H), 6.19–6.20 (m, 1 H, CH), 7.17 (dd, J = 7.2, 7.2 Hz,
1 H, Ar), 7.21 (d, J = 7.2 Hz, 2 H, Ar), 7.31 (dd, J = 7.2, 7.2 Hz,
2 H, Ar) ppm. 13C NMR (100 MHz, CDCl3, TMS): δ = 20.9, 25.1,
39.8, 50.3, 72.8, 119.7, 126.2, 127.3, 128.4, 137.6, 146.0 ppm. IR
(CH Cl ): ν = 3562, 3391, 3084, 3057, 3024, 2956, 2923, 2862, 1679,
˜
2
2
1598, 1490, 1460 cm–1. MS (EI): m/z (%) = 188 (9.8) [M]+, 155
(16.9), 129 (30.1), 117 (21.8), 86 (48.4), 84 (76.0), 51 (35.7), 49
(100.0). HRMS (EI): calcd. for C13H16O [M]+ 188.1201; found
188.1202.
Compound 4aЈ: Yield: 5 mg, 13%. Colorless oil. 1H NMR
(400 MHz, CDCl3, TMS): δ = 1.26 (s, 3 H, CH3), 1.28 (s, 3 H,
CH3), 2.99–3.06 (m, 1 H), 3.21–3.27 (m, 1 H), 3.75 (t, J = 7.2 Hz,
1 H), 6.18 (br. s, 1 H, CH), 7.16 (dd, J = 7.2, 7.2 Hz, 1 H, Ar),
7.22 (d, J = 7.2 Hz, 2 H, Ar), 7.30 (dd, J = 7.2, 7.2 Hz, 2 H, Ar)
ppm. 13C NMR (100 MHz, CDCl3, TMS): δ = 21.4, 21.7, 25.8,
26.0, 37.6, 37.7, 50.2, 50.3, 77.2, 77.9, 119.2, 119.3, 126.1, 127.3,
Scheme 5. A plausible reaction mechanism.
128.4, 137.7, 137.8, 146.2, 146.7 ppm. IR (CH Cl ): ν = 3056, 3024,
˜
2 2
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X.-Y. Tang, M. Shi
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2957, 2926, 2861, 1599, 1492, 1459, 1428, 1380, 1104 cm–1. MS
(EI): m/z (%) = 187 (33.6) [M – 171]+, 171 (48.7), 143 (54.4), 129
(100.0), 128 (32.7), 117 (18.3), 115 (27.5), 91 (28.3). HRMS (EI):
calcd. for C13H16O [M – 170]+ 188.1201; found 188.1200.
44, 7881–7884; t) X. Huang, H. Zhou, Org. Lett. 2002, 4, 4419–
4422.
[3] For the Lewis acid mediated cycloaddition of MCPs with acti-
vated ketone or aldehyde, see: a) M. Shi, B. Xu, Tetrahedron
Lett. 2003, 44, 3839–3842; for the MgI2-mediated ring expan-
sions of methylenecyclopropylamides and imides, see: b) M.
Lautens, W. Han, J. Am. Chem. Soc. 2002, 124, 6312–6316; for
the cycloaddition of MCPs activated by a carbonyl group with
allyltrimethylsilane in the presence of TiCl4, see: c) H. Monti,
D. Rizzotto, G. Leandri, Tetrahedron 1998, 54, 6725–6738; for
the cycloaddition of gem-dialkoxy-substituted MCPs with alde-
hydes and imines upon heating, see: d) S. Yamago, E. Naka-
mura, J. Org. Chem. 1990, 55, 5553–5555; e) S. Yamago, M.
Yanagawa, E. Nakamura, Chem. Lett. 1999, 879–880; for some
related Lewis acid or Brønsted acid mediated reactions of
MCPs, see: f) G. L. N. Peron, J. Kitteringham, J. D. Kilburn,
Tetrahedron Lett. 1999, 40, 3045–3048; g) K. Miura, M. Takas-
umi, T. Hondo, A. Hosomi, H. Saito, Tetrahedron Lett. 1997,
38, 4587–4590; h) G. L. N. Peron, J. Kitteringham, J. D. Kil-
burn, Tetrahedron Lett. 2000, 41, 1615–1618; i) L. Patient,
M. B. Berry, J. D. Kilburn, Tetrahedron Lett. 2003, 44, 1015–
1017; j) G. Peron, D. Norton, J. Kitteringham, J. D. Kilburn,
Tetrahedron Lett. 2001, 42, 347–349; k) L. Patient, M. B. Berry,
S. J. Coles, M. B. Hursthouse, J. D. Kilburn, Chem. Commun.
2003, 2552–2553; l) A. I. Siriwardana, I. Nakamura, Y. Yama-
moto, Tetrahedron Lett. 2003, 44, 4547–4550; m) S. Rajamaki,
J. D. Kilburn, Chem. Commun. 2005, 1637–1639; n) M. Sugin-
ome, T. Matsuda, Y. Ito, J. Am. Chem. Soc. 2000, 122, 11015;
o) M. Suginome, T. Matsuda, T. Yoshimoto, Y. Ito, Org. Lett.
1999, 1, 1567–1569; p) M. Suginome, Y. Ohmori, Y. Ito, Synlett
1999, 1567–1568; q) M. Suginome, T. Matsuda, H. Nakamura,
Y. Ito, Tetrahedron 1999, 55, 8787–8800.
[4] For some of the Lewis acid or Brønsted acid mediated transfor-
mations of MCPs in this laboratory, see: a) M. Shi, B. Xu, Org.
Lett. 2002, 4, 2145–2148; b) J.-W. Huang, M. Shi, Tetrahedron
2004, 60, 2057–2062; c) L.-X. Shao, M. Shi, Eur. J. Org. Chem.
2004, 426–430; d) Y. Chen, M. Shi, J. Org. Chem. 2004, 69,
426–431; e) L.-X. Shao, M. Shi, Adv. Synth. Catal. 2003, 345,
963–966; f) M. Shi, Y. Chen, J. Fluorine Chem. 2003, 122, 219–
227; g) J.-W. Huang, M. Shi, Tetrahedron Lett. 2003, 44, 9343–
9347; h) M. Shi, Y. Chen, B. Xu, J. Tang, Green Chem. 2003,
5, 85–88; i) B. Xu, M. Shi, Org. Lett. 2003, 5, 1415–1418; j) M.
Shi, L.-X. Shao, B. Xu, Org. Lett. 2003, 5, 579–582; k) M. Shi,
Y. Chen, B. Xu, J. Tang, Tetrahedron Lett. 2002, 43, 8019–8024;
l) J.-W. Huang, M. Shi, Synlett 2004, 2343–2346; m) L.-X.
Shao, J.-W. Huang, M. Shi, Tetrahedron 2004, 60, 11895–11901;
n) E. B. Verina, K. N. Sedenkova, I. S. Borisov, Y. K. Grishin,
T. S. Kuznetsova, N. S. Zefirov, Tetrahedron 2009, 65, 5693–
5701.
Supporting Information (see footnote on the first page of this arti-
cle): General remarks, reaction procedures, and spectroscopic data
of all prepared compounds.
Acknowledgments
We thank the Shanghai Municipal Committee of Science and Tech-
nology (08dj1400100-2), the National Basic Research Program of
China [(973)-2009CB825300], and the National Natural Science
Foundation of China (20872162, 20672127, 20732008, 20821002,
and 20702013) for financial support.
[1] For recent reviews on MCPs, see: a) M. Lautens, W. Klute,
W. Ta m , Chem. Rev. 1996, 96, 49–92; b) A. de Meijere, S. I.
Kozhushkov, A. F. Khlebnikov, Top. Curr. Chem. 2000, 207,
89–147; c) P. Binger, P. Wedemann, S. I. Kozhushkov, A.
de Meijere, Eur. J. Org. Chem. 1998, 113–119; d) A. de Meijere,
S. I. A. Kozhushkov, Eur. J. Org. Chem. 2000, 3809–3822; e) I.
Nakamura, Y. Yamamoto, Adv. Synth. Catal. 2002, 344, 111–
129; f) A. Brandi, S. Cicchi, F. M. Cordero, A. Goti, Chem.
Rev. 2003, 103, 1213–1270; g) E. Nakamura, S. Yamago, Acc.
Chem. Res. 2002, 35, 867–877; h) L.-X. Shao, M. Shi, Curr.
Org. Chem. 2007, 11, 1135–1137; i) M. Rubin, M. Rubina, V.
Gevorgyan, Chem. Rev. 2007, 107, 3117–3179; j) S. Yamago, E.
Nakamura, Org. React. 2002, 61, 1–217; k) A. de Meijere, S. I.
Kozhushkov, T. Spath, M. von Seebach, S. Lohr, H. Nuske, T.
Pohomann, M. Es-Sayed, S. Brase, Pure Appl. Chem. 2000, 72,
1745–1756.
[2] For selected examples on the reactions of MCPs, see: a) B. Hu,
S. Y. Xing, Z. W. Wang, Org. Lett. 2008, 10, 5481–5484; b) M.
Shi, L.-P. Liu, J. Tang, Org. Lett. 2006, 8, 4043–4046; c) M.
Shi, B. Xu, J.-W. Huang, Org. Lett. 2004, 6, 1175–1178; d) X.
Huang, Y. Yang, Org. Lett. 2007, 9, 1667–1670; e) M. Lautens,
W. Han, J. H. Liu, J. Am. Chem. Soc. 2003, 125, 4028–4029; f)
M. Lautens, Y. Ren, J. Am. Chem. Soc. 1996, 118, 10668–
10669; g) L. Yu, J. D. Meng, L. Xia, R. Guo, J. Org. Chem.
2009, 74, 5087–5089; h) S. Ma, J. Zhang, Angew. Chem. 2003,
115, 193–197; Angew. Chem. Int. Ed. 2003, 42, 183–187; i) S.
Ma, L. Lu, J. Zhang, J. Am. Chem. Soc. 2004, 126, 9645–
9660Ͼ; j) L. Lu, G. Chen, S. Ma, Org. Lett. 2006, 8, 835–838;
k) M. E. Scott, M. Lautens, J. Org. Chem. 2008, 73, 8154–8162;
l) C. Taillier, M. Lautens, Org. Lett. 2007, 9, 591–593; m) E.
Smolensky, M. Kapon, M. S. Eisen, Organometallics 2007, 26,
4510–4527; n) V. V. Diev, T. Q. Tung, A. P. Molchanov, Eur. J.
Org. Chem. 2009, 525–530; o) B. Hu, J. L. Zhu, S. Y. Xing, J.
Fang, D. Du, Z. W. Wang, Chem. Eur. J. 2009, 15, 324–327; p)
V. Bagutski, A. de Meijere, Adv. Synth. Catal. 2007, 349, 1247–
1255; q) X.-C. Hang, Q.-Y. Chen, J.-C. Xiao, Eur. J. Org. Chem.
2008, 1101–1106; r) I. Nakamura, B. H. Oh, S. Saito, Y. Yama-
moto, Angew. Chem. 2001, 113, 1338–1340; Angew. Chem. Int.
Ed. 2001, 40, 1298–1300; s) T. Kurahashi, A. de Meijere, An-
gew. Chem. 2005, 117, 8039–8096; Angew. Chem. Int. Ed. 2005,
[5] L.-F. Yao, Y. Wei, M. Shi, J. Org. Chem. 2009, 74, 9466–9469.
[6] P. Cordier, C. Aubert, M. Malacria, E. Lacote, V. Gandon,
Angew. Chem. 2009, 121, 8913–8916; Angew. Chem. Int. Ed.
2009, 48, 8757–8760.
[7] This is a known compound and its spectroscopic data are con-
sistent with those reported in the literature: G. W. Kabalka, Y.-
H. Ju, Z.-Z. Wu, J. Org. Chem. 2003, 68, 7915–7917.
[8] T. M. Khomenko, I. Yu. Bagryanskaya, Yu. V. Gatilov, D. V.
Korchagina, V. P. Gatilova, Zh. V. Dubovenko, V. A. Barkhash,
Zh. Org. Khim. 1985, 21, 677–678.
Received: April 14, 2010
Published Online: May 31, 2010
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