One-pot synthesis of (E)-styryl ketones from styrenes

Article abstract of DOI:10.1021/jo201036x

A new, efficient protocol for the highly stereoselective one-pot synthesis of (E)-styryl ketones from styrenes based on sequential ruthenium-catalyzed silylative coupling-rhodium-catalyzed desilylative acylation reactions is reported.

Full text of DOI:10.1021/jo201036x

NOTE
pubs.acs.org/joc
One-Pot Synthesis of (E)-Styryl Ketones from Styrenes
Piotr Pawluꢀc,* Justyna Szudkowska, Grzegorz Hreczycho, and Bogdan Marciniec
Department of Organometallic Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland
S Supporting Information
b
ABSTRACT: A new, efficient protocol for the highly stereo-
selective one-pot synthesis of (E)-styryl ketones from styrenes
based on sequential ruthenium-catalyzed silylative couplingÀ
rhodium-catalyzed desilylative acylation reactions is reported.
nsaturated ketones have been widely applied as
R,β-Uuseful key reagents in organic synthesis.1 Their
use as substrates for a number of reactions such as Michael
addition,1 hydrogenation,2 epoxidation,3 cycloaddition,4 MoritaÀ
BaylisÀHillman reaction,5 etc., has stimulated their synthetic
advancements.
The most common access to (E)-R,β-unsaturated ketones is
by the ClaisenÀSchmidt condensation of aldehydes and ketones
under basic conditions.6 However, this method suffers from the
drawbacks of narrow substrate diversity, the reversibility of the
aldol addition, and side reactions such as isomerization, ketone
self-condensation, and Michael addition. An elegant solution to
these problems is a Mukaiyama aldol reaction followed by
subsequent dehydration catalyzed by a Lewis acid7 or catalytic
aldol condensation between alkenyl trichloroacetates and alde-
hydes reported by Yanagisawa et al.8 Alternatively, stereodefined
R,β-unsaturated ketones may be formed by selective oxidation of
allylic alcohols9 or FriedelÀCrafts acylation of arenes by R,
β-unsaturated acyl chlorides.10
In addition, a number of transition-metal-catalyzed methodol-
ogies for the preparation of (E)-R,β-unsaturated ketones have
been developed over the last two decades. R,β-Unsaturated
ketones may be formed by the selective ruthenium-catalyzed
cross-metathesis of vinyl ketones with terminal alkenes11 or
rhodium-catalyzed carbonylative addition of arylboronic acids
to terminal alkynes.12 Palladium-catalyzed Heck-type coupling of
vinyl ketone derivatives with iodoarenes13 or aryl boronic acids14
are also valuable CÀC bond-forming reactions, which allow the
formation of R,β-unsaturated ketones; however, the poor avail-
ability and stability of vinyl ketones and the competitive con-
jugate addition reaction limit their use. A new catalytic approach
based on palladium-catalyzed carbonylative Heck reaction of aryl
halides or aryl triflates and styrenes has been also recently
reported by Beller and co-workers.15
In the past two decades, we have developed the silylative
coupling of olefins with vinyl-substituted organosilicon com-
pounds occurring in the presence of complexes containing initially
or generatingin situ MÀH and MÀSi bonds.16 The mechanism of
the process proposed for the Ru complexes proceeds via inser-
tion of vinylsilane into RuÀH bond and β-Si transfer to the metal
with elimination of ethylene to generate RuÀSi species, followed
by insertion of alkene and β-H transfer to the metal with
elimination of the substituted vinylsilane (Scheme 1).16
The silylative coupling, in combination with subsequent
desilylation reactions such as Hiyama cross-coupling and halo-
desilylation appears to be a valuable step to provide functional-
ized unsaturated organic compounds such as (E)-stilbenes, aryl-
substituted polyenes, or (E)-styryl halides.17
On the other hand, acylation of stereodefined vinylsilanes by
acid halides in the presence of Lewis acids proceeds in a regiose-
lective manner to afford R,β-unsaturated ketones.18 Recently,
Narasaka and co-workers developed a catalytic acylation of vinyl-
silanes with acid anhydrides by the use of a rhodium complex
which avoids the use of large quantities of strong Lewis acids and
highly reactive and harmful acid halides.19 The mechanism of the
catalytic acylation proceeds via transmetalation between the
Rh(I) complex and vinylsilane to afford vinylrhodium intermedi-
ate, followed by sequential oxidative addition of acid anhydride
and reductive elimination of R,β-unsaturated ketone with regen-
eration of Rh(I) catalyst (Scheme 2).19a
The sequential Hiyama cross-coupling/Narasaka acylation
reactions have been also successfully applied to the synthesis of
R,β-unsaturated carbonyl motifs.20 This catalytic acylation pro-
tocol has been developed mostly for dimethylphenyl-substituted
vinylsilanes, which appears to be more reactive than vinylsilanes
with trimethylsilyl groups under the given conditions (1,4-dioxane,
90 °C). However, in spite of the availability and stability of the
unsaturated trimethylsilyl derivatives, the development of the
conditions for their selective conversion to stereodefined R,
β-unsaturated ketones is of significance.
We have envisaged that the ruthenium-catalyzed E-selective
silylative coupling of styrenes with trimethylvinylsilane followed
by rhodium-catalyzed acylation can be a valuable and comple-
mentary synthetic method for one-pot conversion of styrenes
into (E)-styryl ketones (Scheme 3). Therefore, in this paper, we
report a facile one-pot preparation of (E)-styryl ketones from
Received: May 23, 2011
Published: June 30, 2011
r
2011 American Chemical Society
6438
dx.doi.org/10.1021/jo201036x J. Org. Chem. 2011, 76, 6438–6441
|

The Journal of Organic Chemistry
NOTE
Scheme 1. Silylative Coupling Mechanism
Scheme 3. Proposed Synthesis of (E)-Styryl Ketones
Since both reactions, i.e., silylative coupling and desilylative
acylation, can be performed in toluene, this result prompted us to
attempt the acylation step in one pot with silylative coupling
without further purification of the (E)-styrylsilane intermediate.
In a typical procedure, 4-chlorostyrene, trimethylvinylsilane (1:1
ratio), and RuHCl(CO)(PPh3)3 catalyst (1 mol %) were dis-
solved in toluene (0.5 M concentration) and heated in a Schlenk
bomb flask fitted with a plug valve at 100 °C for 6 h under Ar
atmosphere. Next, after the reaction was cooled to room tempera-
ture, 3 equiv of acetyl anhydride and 5 mol % of solid
[RhCl(CO)2]2 were added, and the reaction mixture was heated
to 120 °C. Treatment of the silylative coupling product with
anhydride caused acylation in a stereospecific manner giving
(E)-4-chlorostyryl methyl ketone in high geometrical purity
(E/Z = 99/1) within 18 h. Column chromatography of the
resulting product (silica gel, eluent: hexane/diethyl ether 8:2)
afforded pure (E)-4-chlorostyryl methyl ketone 1 in 90% overall
yield (entry 1, Table 1).
Scheme 2. Mechanism of the Rhodium-Catalyzed Acylation
of Vinylsilanes
Given our optimized conditions, we investigated the scope of
this one-pot reaction sequence using various substituted styrenes
and selected carboxylic acid anhydrides (Table 1). Since the
synthetic procedure requires the absence of byproducts of the
homo-coupling of trimethylvinylsilaneÀ1,2-bis(trimethylsilyl)-
ethenes which could form diketone side products, all the
silylative coupling reactions were performed at the 1:1 ratio of
substrates. Moreover, the silylative coupling reactions were
carried out in a 0.5 M solution of toluene to minimize polym-
erization of styrenes. Under these conditions, substituted styrenes
bearing functional groups such as ÀMe, ÀOMe, ÀCl, and ÀBr
reacted successfully to give the corresponding (E)-styryl ketones
in high yields, irrespective of the substituent’s electronic character
and position in the aromatic ring (Table 1). Both saturated and
unsaturated acid anhydrides can be employed for the acylation of
(E)-styrylsilanes to give corresponding (E)-styryl ketones with
moderate to high yields. However, when butyric and benzoic
anhydride were applied as the acylating agents (Table 1, entries
4À7), the reaction required a longer time (40À48 h). Moreover,
in the reactions with benzoic anhydride, z excellent. In all cases,
the E-double bond geometry was strongly favored, with approxi-
mately 99:1 E/Z ratio as measured by 1H NMR.
Efforts were made to further improve the procedure by
examining tandem catalysis using one catalyst for both silylative
coupling and acylation steps. Unfortunately, the silylative cou-
pling of styrenes with vinyltrimethylsilane in the presence of
[RhCl(CO)2]2 was unsuccessful. Other rhodium precursors
which are known to be active in the silylative coupling reaction,23
e.g., [RhCl(cod)]2, [Rh(OSiMe3)(cod)]2, and RhH(CO)(PPh3)3,
also failed as potential Narasaka acylation catalysts.
In summary, we have devised a new versatile one-pot protocol
for stereoselective preparation of (E)-styryl ketones via a highly
selective catalytic silylative coupling/desilylative acylation se-
quence. Starting from easily available and inexpensive styrenes,
vinylsilane, and carboxylic acid anhydrides the corresponding
styrenes via the corresponding (E)-styryltrimethylsilane
intermediates.
As we have previously reported, the silylative coupling of
substituted styrenes with vinylsilanes catalyzed by rutheniumÀ
hydride or rutheniumÀsilyl complexes occurred stereoselectively
to give (E)-β-silylstyrenes in high yields.21 For preliminary results
on the silylative coupling reaction, equimolar amounts of the
commercially available 4-chlorostyrene and trimethylvinylsilane
were used, and the reaction was conducted following the original
procedure (RuHCl(CO)(PPh3)3 catalyst (1 mol %) toluene, 6 h,
100 °C, sealed ampule)21a to give exclusively (E)-4-chlorostyryl-
trimethylsilane (GC yield 98%). Treatment of the isolated (E)-4-
chlorostyryltrimethylsilane with 3 equiv of acetic anhydride in the
presence of rhodium catalyst [RhCl(CO)2]2 (5 mol %) in dry 1,4-
dioxane at 90 °C for 24 h under Ar atmosphere according to the
method described by Narasaka and co-workers19 allowed isolation
of stereochemically pure (E)-4-chlorostyryl methyl ketone in 70%
yield. Thus, by sequencing the highly E-selective silylative coupling
of 4-chlorostyrene with a stereospecific acylation, the stereochem-
ical fidelity of the product is preserved.
Since a single example of the efficient acylation of (E)-
dimethylphenyl(4-phenylbut-1-en-1-yl)silane by acetic anhydride
in toluene has been reported by Narasaka and co-workers,19b we
tested this solvent for the desilylative acylation of styrylsilanes.
After several attempts, we found that acylation of (E)-4-chloros-
tyryltrimethylsilane by acetic anhydride in the presence of rhodium
catalyst in dry toluene occurs more efficiently (95% GC yield) at
higher temperature (120 °C) in a closed reaction vessel without
affecting the stereoselectivity of the process.
6439
dx.doi.org/10.1021/jo201036x |J. Org. Chem. 2011, 76, 6438–6441

The Journal of Organic Chemistry
NOTE
Table 1. One-Pot Synthesis of (E)-Styryl Ketones from
Styrenes
165 (100), 145 (52), 137 (60), 102 (77), 75 (43), 50 (30). HRMS calcd
for C10H9ClO: 180.03419, found 180.03370.
(E)-4-(4-Bromophenyl)but-3-en-2-one24 (2). Yield: 93%. H
1
NMR (300 MHz, CDCl3): δ = 2.38 (s, 3H), 6.70 (d, 1H, J = 16.3 Hz),
7.38À7.55 (m, 5H). 13C NMR (75 MHz, CDCl3): δ = 27.7, 127.5,
124.7, 129.3, 129.4, 132.2, 141.9, 198.1. MS m/z (rel int): 226 (M+ 30),
211 (54), 183 (30), 145 (75), 130 (22), 102 (100), 75 (25), 50 (30).
HRMS calcd for C10H9BrO: 223.98368, found 223.98297.
(E)-4-(4-methoxyphenyl)but-3-en-2-one24 (3). Yield: 80%.
1H NMR (300 MHz, CDCl3): δ = 2.36 (s, 3H), 3.84 (s, 3H), 6.61 (d,
1H, J = 16.2 Hz), 6.91À6.34 (m, 2H), 7.45À7.52 (m, 3H). 13C NMR
(75 MHz, CDCl3): δ = 30.9, 55.4, 114.4, 125.0, 127.1, 161.6, 129.6,
143.3, 206.9. MS m/z (rel int): 176 (M+, 42), 161 (100), 145 (20), 133
(52), 118 (25), 89 (21), 77 (22), 63 (20). HRMS calcd for C11H12O2:
176.08373, found 176.08310.
(E)-1-Phenyl-3-(3-tolyl)prop-2-en-1-one25 (4). Yield: 70%.
1H NMR (300 MHz, CDCl3): δ = 2.33 (d, 3H), 7.14À7.34 (m, 3H),
7.36À7.54 (m, 5H), 7.72 (d, 1H, J = 15.7 Hz), 7.94À7.97 (m, 2H). 13C
NMR (75 MHz, CDCl3): δ = 21.3, 125.7, 128.5, 128.6, 128.8, 129.1,
131.4, 132.7, 134.8, 138.3, 138.6, 121.8, 145.1, 190.6. MS m/z (rel int):
221 (M+, 45), 207 (100), 180 (15), 145 (15), 115 (30), 89 (21), 77 (25),
20 (20). HRMS calcd for C16H14O: 222.10447, found 222.10310.
(E)-3-(4-Bromophenyl)-1-phenylprop-2-en-1-one26 (5). Yield:
83%. 1H NMR (300 MHz, CDCl3): δ = 7.49À7.62 (m, 8H), 7.75 (d, 1H,
J = 15.8 Hz), 8.04 (dd, 2H, J = 8.2, 1.2 Hz). 13C NMR (75 MHz, CDCl3):
δ= 122.5, 128.5, 128.7, 129.2, 129.8, 130.2, 132.2, 133.0, 133.8, 143.4, 190.2.
MS m/z (rel int): 286 (M+, 60), 207 (100), 179 (50), 178 (35), 130 (32),
105 (33), 102 (85), 77 (87), 51 (55). HRMS calcd for C15H11BrO:
285.99933, found 285.99725.
(E)-3-(4-Chlorophenyl)-1-phenylprop-2-en-1-one26 (6). Yield:
70%. 1H NMR (300 MHz, CDCl3):δ=7.39(d, 2H, J= 8.4 Hz), 7.47À7.60
(m, 6H), 7.65À7.79 (m, 1H), 8.00À8.18 (m, 2H). 13C NMR (75 MHz,
CDCl3): δ = 122.4, 128.5, 128.7, 128.9, 129.2, 129.6, 130.5, 132.9, 134.5,
143.3, 190.4. MS m/z (rel int): 242 (M+, 80), 208 (75), 179 (50), 165 (45),
130 (25), 102 (50), 77 (100), 51 (70). HRMS calcd for C15H11ClO:
242.04984, found 242.04932.
(E)-1-(4-Methoxyphenyl)hex-1-en-3-one24 (7). Yield: 72%.
1H NMR (300 MHz, CDCl3): δ = 0.95À1.00 (t, 3H, J = 7.3 Hz),
1.58À1.74 (m, 2H), 2.60À2.65 (t, 2H, J = 7.2 Hz), 3.84 (s, 3H), 6.63 (d,
1H, J = 16.2 Hz), 6.89À6.93 (m, 2H), 7.49À7.54 (m, 3H). 13C NMR
(75 MHz, CDCl3): δ = 13.9, 17.9, 42.7, 55.4, 114.4, 124.2, 127.2, 161.5,
129.9, 142.1, 200.6. MS m/z (rel int): 204 (M+, 30), 161 (60), 133 (26),
118 (10), 89 (12), 77 (12), 63 (13). HRMS calcd for C13H16O2:
204.11448, found 204.11504.
a Overall yield of isolated products. b GC yield.
unsaturated ketones are obtained in generally good yields and
selectivities.
(E)-1-(4-Bromophenyl)-4-methylpenta-1,4-dien-3-one27 (8).
Yield: 72%. 1H NMR (300 MHz, CDCl3): δ = 2.00 (s, 3H), 5.86 (s, 1H),
6.03 (s, 1H), 7.28 (d, 1H, J = 15.8 Hz), 7.40À7.46 (d, 2H, J = 8.4 Hz),
7.51À7.61 (m, 3H). 13C NMR (75 MHz, CDCl3): δ = 18.1, 121.7, 124.5,
124.7, 129.6, 132.1, 133.8, 142.1, 145.6, 191.6. MS m/z (rel int): 250 (M+
30%), 211 (60), 181 (25), 171 (75), 128 (30), 102 (100), 75 (35). HRMS
calcd for C12H11BrO: 249.99832, found 249.99933.
’ EXPERIMENTAL SECTION
General Procedure for the Synthesis of (E)-Styryl Ketones.
A mixture consisting of 5 mmol of substituted styrene, 0.5 g (5 mmol) of
vinyltrimethylsilane, 47.6 mg (0.05 mmol) of RuHCl(CO)(PPh3)3, and
10 mL of dry toluene was placed under Ar atmosphere in a Schlenk
bomb flask fitted with a plug valve and heated at 100 °C for 6 h. After the
reaction was completed (GC analysis), 0.25 mmol (97.20 mg) of
[RhCl(CO)2]2 and 15 mmol of anhydride were added. The mixture
was stirred for 24À48 h (see Table 1) at 120 °C. After this time the
solvent was evaporated and the crude product was purified by column
chromatography on silica gel, eluting with n-hexane/diethyl ether in a
ratio of 8:2 to give the corresponding ketone.
(E)-1-(4-Chlorophenyl)-4-methylpenta-1,4-dien-3-one27 (9).
Yield: 74%. 1H NMR (300 MHz, CDCl3): δ = 1.93 (s, 3H), 5.78À5.79
(m, 1H), 5.96 (s, 1H), 7.19 (d, J = 15.9 Hz, 1H), 7.28À7.31 (m, 2H),
7.43À7.45 (m, 2H), 7.52 (d, J = 15.9 Hz, 1H). 13C NMR (75 MHz,
CDCl3): δ = 18.6, 121.7, 124.6, 129.1, 133.4, 142.0, 129.4, 136.1, 145.5,
191.5. MS m/z (rel int): 206 (M+, 20), 171 (50), 165 (100), 137 (50), 102
(45), 76 (15), 50 (10). HRMS calcd for C12H11ClO: 206.04984, found.
206.05146
(E)-1-(3-Methoxyphenyl)-4-methylpenta-1,4-dien-3-
one27 (10). Yield: 68%. 1H NMR (300 MHz, CDCl3): δ = 1.98À2.04
(m, 3H), 3.84 (s, 3H), 5.84À5.85 (m, 1H), 6.03 (s, 1H), 6.94À6.97
(m, 1H), 7.08À7.10 (m, 1H), 7.17À7.24 (m, 2H), 7.26À7.32 (m, 1H),
7.62 (d, J = 15.7 Hz, 1H). 13C NMR (75 MHz, CDCl3): δ = 18.1, 55.3,
(E)-4-(4-Chlorophenyl)but-3-en-2-one24 (1). Yield: 90%. H
NMR (300 MHz, CDCl3): δ = 2.31 (s, 3H,), 6.65 (d, 1H, J = 16.3 Hz),
7.29À7.43 (m, 5H). 13C NMR (75 MHz, CDCl3): δ = 27.7, 127.4,
129.2, 129.4, 132.9, 136.4, 141.8, 198.1. MS m/z (rel int): 180 (M+, 30),
1
6440
dx.doi.org/10.1021/jo201036x |J. Org. Chem. 2011, 76, 6438–6441

The Journal of Organic Chemistry
NOTE
120.9, 113.3, 115.9, 121.6, 124.4, 145.9, 159.6, 129.8, 143.4, 145.5, 192.0.
MS m/z (rel int): 202 (M+, 40), 174 (65), 161 (100), 159 (45), 133
(48), 118 (52), 103 (27), 89 (35), 63 (34). HRMS calcd for C13H14O2:
202.09938, found 202.09914.
(c) Wu, X.-F.; Jiao, H.; Neumann, H.; Beller, M. ChemCatChem 2011,
3, 726–733.
(16) For recent reviews, see: (a) Marciniec, B. Acc. Chem. Res. 2007,
40, 943–952. (b) Marciniec, B. Coord. Chem. Rev. 2005, 249, 2374–2390.
(17) Pawluꢀc, P.; Prukaza, W.; Marciniec, B. Eur. J. Org. Chem. 2010,
2, 219–229 and references cited therein.
(18) (a) Fleming, I.; Pearce, A. J. Chem. Soc., Chem. Commun.
1975, 633–634. (b) Paquette, L. A.; Fristad, W. E.; Dime, D. S.; Bailey,
T. R. J. Org. Chem. 1980, 45, 3017–3028. (c) Tubul, A.; Santell, M.
Tetrahedron 1988, 44, 3975–3982. (d) Sasaki, T.; Nakanishi, A.; Ohno,
M. J. Org. Chem. 1982, 47, 3219–3224. (e) Perrone, S.; Knochel, P. Org.
Lett. 2007, 9, 1041–1044.
’ ASSOCIATED CONTENT
S
Supporting Information. NMR spectra of compounds
b
1À10. This material is available free of charge via the Internet at
http://pubs.acs.org.
’ AUTHOR INFORMATION
(19) (a) Yamane, M.; Uera, K.; Narasaka, K. Chem. Lett. 2004,
33, 424–425. (b) Yamane, M.; Uera, K.; Narasaka, K. Bull. Chem. Soc. Jpn.
2005, 78, 477–486.
Corresponding Author
*E-mail: piotrpaw@amu.edu.pl
(20) Thiot, C.; Mioskowski, Ch.; Wagner, A. Eur. J. Org. Chem.
2009, 3219–3227.
(21) (a) Marciniec, B; Pietraszuk, C. Organometallics 1997, 16,
4320–4326. (b) Itami, Y.; Marciniec, B.; Majchrzak, M.; Kubicki, M.
Organometallics 2003, 22, 1835–1842. (c) Marciniec, B.; Pietraszuk, C.;
Jankowska, M. Pol. Pat. 2002, P-355–875.
(22) Sugihara, T.; Satoh, T.; Miura, M.; Nomura, M. Angew. Chem.,
Int. Ed. 2003, 42, 4672–4674.
’ ACKNOWLEDGMENT
Financial support from the Ministry of Science and Higher
Education (Poland), Grant No. N204 148540, is gratefully
acknowledged.
(23) (a) Marciniec, B.; Walczuk-Guꢀsciora, E.; Pietraszuk, C. Orga-
nometallics 2001, 20, 3423–3428. (b) Marciniec, B.; Walczuk-Guꢀsciora,
E.; Pietraszuk, C. Catal. Lett. 1998, 55, 125–127.
(24) McConville, M.; Saidi, O.; Blacker, J.; Xiao, J. J. Org. Chem.
2009, 74, 2692–2698.
(25) Karaman, I.; Gezegen, H.; Burcu G€urdere, M.; Dingil, A.;
Ceylan, M. Chem. Biodiv. 2010, 7, 400–408.
(26) Peppe, C.; Pavao das Chagas, R. J. Organomet. Chem. 2006, 691,
5868–5872.
’ REFERENCES
(1) For reviews, see: (a) Sibi, M. P.; Manyem, S. Tetrahedron 2000,
56, 8033–8061. (b) Krause, N.; Hoffmann-Roder, A. Synthesis 2001,
171–196. (c) Almasi, D.; Alonso, D. A.; Najera, C. Tetrahedron:
Asymmetry 2007, 18, 299–365. (d) Taylor, M. S.; Jacobsen, E. N. Angew.
Chem., Int. Ed. 2006, 45, 1520–1543.
(2) Recent examples: (a) Martin, N. J. A.; List, B. J. Am. Chem. Soc.
2006, 128, 13368–13369. (b) Lu, W.-J.; Chen, Y.-W.; Hou, X.-L. Angew.
Chem., Int. Ed. 2008, 47, 10133–10136. (c) Shibahara, F.; Bower, J. F.;
Krische, M. J. J. Am. Chem. Soc. 2008, 130, 14120–14122.
(3) (a) Xia, Q.-H.; Ge, H.-Q.; Ye, C.-P.; Liu, Z.-M.; Su, K.-X. Chem.
Rev. 2005, 105, 1603–1662. (b) Hinch, M.; Jacques, O.; Drago, C.;
Caggiano, L.; Jackson, R. F. W.; Dexter, C.; Anson, M. S.; Macdonald,
S. J. F. J. Mol. Catal. 2006, 251, 123–128. (c) Reisinger, C. M.; Wang, X.;
List, B. Angew. Chem., Int. Ed. 2008, 47, 8112–8115.
(27) McDougal, N. T.; Schaus, S. E. Angew. Chem., Int. Ed. 2006, 45,
3117–3119.
(4) (a) Barluenga, J.; Fanlo, H.; Lopez, S.; Florez, J. Angew. Chem.,
Int. Ed. 2007, 46, 4136–4140. (b) Huang, X.; Zhang, L. J. Am. Chem. Soc.
2007, 129, 6398–6399. (c) Hernandez-Toribio, J.; Arrayas, R. G.;
Martin-Matute, B.; Carretero, J. C. Org. Lett. 2009, 11, 393–396.
(5) Basavaiah, D.; Jaganmohan Rao, A.; Satyanarayana, T. Chem. Rev.
2003, 103, 811–892.
(6) (a) Heathcock, C. H. In Comprehensive Organic Synthesis; Trost.,
B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 2, pp
131À179.
(7) Ishihara, K.; Kurihara, H.; Yamamoto, H. Synlett 1997, 597–599.
(8) Yanagisawa, A.; Goudu, R.; Arai, T. Org. Lett. 2004, 6, 4281–4283.
(9) Shibuya, M.; Ito, S.; Takahashi, M.; Iwabuchi, Y. Org. Lett. 2004,
6, 4303–4306.
(10) (a) Yin, W.; Ma, Y.; Xu, J.; Zhao, Y. J. Org. Chem. 2006, 71,
4312–4315. (b) Taylor, M. S.; Zalatan, D. N.; Lerchner, A. M.; Jacobsen,
E. N. J. Am. Chem. Soc. 2005, 127, 1313–1317. (c) Haynes, R. K.; Jackson,
W. R.; Stragalinou, A. Aust. J. Chem. 1980, 33, 1537–1544.
(11) Chatterjee, A. K.; Toste, F. D.; Choi, T. L.; Grubbs, R. H. Adv.
Synth. Catal. 2002, 344, 634–637.
(12) Dheur, J.; Sauthier, M.; Castanet, Y.; Mortreux, A. Adv. Synth.
Catal. 2007, 349, 2499–2506.
(13) (a) Botella, L.; Najera, C. Tetrahedron Lett. 2004, 45, 1833–1836.
(b) Bianco, A.; Cavarischia, C.; Guiso, M. Eur. J. Org. Chem. 2004,
2894–2898.
(14) Yoo, K. S.; Yoon, C. H.; Jung, K. W. J. Am. Chem. Soc. 2006,
128, 16384–16399.
(15) (a) Wu, X.-F.; Neumann, H.; Spannenberg, A.; Schulz, T.; Jiao,
H.; Beller, M. J. Am. Chem. Soc. 2010, 132, 14596–14602. (b) Wu, X.-F.;
Neumann, H.; Beller, M. Angew. Chem., Int. Ed. 2010, 49, 5284–5288.
6441
dx.doi.org/10.1021/jo201036x |J. Org. Chem. 2011, 76, 6438–6441