Synthesis of polycyclic heterocycles via sequential Au-catalyzed cycloisomerization and Ru-catalyzed metathesis reactions

Article abstract of DOI:10.1016/j.tetlet.2009.04.001

A sequential and efficient catalytic preparation of polycyclic heterocycles, including tetrahydro furo- or cyclopenta- pyran, hexahydropyrano pyrrolidine, and tetrahydroisochromene derivatives is described based on a gold-catalyzed cycloisomerization reac

Full text of DOI:10.1016/j.tetlet.2009.04.001

Tetrahedron Letters 50 (2009) 3719–3722
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Tetrahedron Letters
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Synthesis of polycyclic heterocycles via sequential Au-catalyzed cycloisomer-
ization and Ru-catalyzed metathesis reactions
*
Chung-Meng Chao, Patrick Yves Toullec, Véronique Michelet
Laboratoire de Synthèse Sélective Organique et Produits Naturels, ENSCP, UMR 7573, 11 rue P. et M. Curie, F-75231 Paris Cedex 05, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A sequential and efficient catalytic preparation of polycyclic heterocycles, including tetrahydro furo- or
cyclopenta- pyran, hexahydropyrano pyrrolidine, and tetrahydroisochromene derivatives is described
based on a gold-catalyzed cycloisomerization reaction followed by a Ru-catalyzed ring-closing metathe-
sis. An isomerization of the alkene moiety leading diastereoselectively to cis tetrahydrocyclopen-
ta[c]pyran and tetrahydro-1H-furo[3,4-c]pyran is observed in some cases. The catalytic hydrogenation
reactions of these tetrahydropyrans led to the formation of polycyclic-functionalized saturated
compounds.
Received 3 February 2009
Accepted 1 April 2009
Available online 5 April 2009
Ó 2009 Elsevier Ltd. All rights reserved.
The transition metal-catalyzed reactions and specifically homo-
geneous catalysis have given a considerable impetus to the pro-
gress of the area of organometallic, organic, and industrial
chemistries.1 Among them, carbon–carbon and carbon–oxygen
bond formations using gold2 and ruthenium3 organometallic cata-
lysts are fundamentally important because they provide successful
solutions to environmental, economic concerns. Whereas gold
catalysis was only recognized recently for the promotion of a myr-
iad of transformations, ruthenium catalysis and more specifically
ruthenium-catalyzed metathesis4 has been well established as an
important tool for the organic chemist. As part of our ongoing pro-
gram toward the development of catalytic cycloisomerization reac-
tions,5 we have been interested in the synthesis of polycyclic
derivatives and we have envisaged to test a sequential gold-cata-
lyzed alkoxycyclization with a ruthenium-catalyzed ring-closing
metathesis reaction. We and others have indeed described metal-
catalyzed alkoxycyclization of enynes leading to cyclic ethers
(Scheme 1, Eq 1).5,6 We anticipated that allylic derivatives might
be engaged in Ru-catalyzed metathesis leading to bicyclic deriva-
tives (Scheme 1, Eq 2). The resulting heterocycles would be valu-
able skeleton for the synthesis of natural and/or pharmaceutical
product derivatives.7 Further hydrogenation reaction would then
potentially allow the preparation of polycyclic heterocycles
(Scheme 1, Eq. 3), controlling therefore three stereogenic centers
by catalytic reactions. The sequential gold-catalyzed cycloisomer-
ization/ring-closing metathesis has been scarcely described in the
literature8 and only concerned the ring-closing metathesis reac-
tions of a diene resulting from the addition of an allylsilane to
1,6-enynes8a or a methoxycyclized bearing a geranyl and allyl side
chains.8b These strategies respond to environmental concerns and
contribute to the concept of green chemistry.1
As gold catalysts have been described for the alkoxycyclization
step,5,6 we tested the allyloxycyclization reaction on various eny-
nes. The catalyst combining Au(III)/PPh3 and various silver salts
was chosen for this study and the reaction was conducted in allylic
alcohol which is used as a solvent at room temperature (Table 1).
The addition of allylic alcohol was successfully realized on carbo-
and heteroatom-linked 1,6-enynes (Table 1, entries 1–5). The
allylic ethers 2a–e were isolated in good to excellent yield. In the
same manner as previously reported, one diastereomer was iso-
lated for 2a, 2b, and 2e. The lower reactivity of nitrogen-tethered
enynes9,5c prompted us to test the silver bis(trifluoromethanesul-
fonyl)imidate as an halide-abstracting agent (Table 1, entries 4
and 5). The corresponding ethers were thus prepared under mild
R2
OR
[M] =
R2
R1
H
R1
Pd, Pt, Hg, Au, Ru
Eq. 1
Z
Z
Z
ROH, rt-80 ºC
[M] = Ru
R1 R2
O
H
R2
R1
H
O
Eq. 2
Eq. 3
Z
R1 R2
O
R1 R2
H
H
[M] = Pd
O
Z
Z
H
* Corresponding author. Tel.: +33 1 44276742; fax: +33 1 44071062.
E-mail address: veronique-michelet@enscp.fr (V. Michelet).
Scheme 1.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.04.001

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C.-M. Chao et al. / Tetrahedron Letters 50 (2009) 3719–3722
Table 1
Gold-catalyzed allyloxycyclization reaction of enynes 1c–j
R2
O
R2
R1
H
Conditions
rt, allylOH
R1
Z
Z
1a-j
2a-j
Entry
1
Enyne 1
Conditions
t (h)
Product 2
Yielda (%)
2a
O
1a
O
H
H
O
O
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgSbF6
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgOTf
2
2.5
79
66
O
O
O
2b
O
O
1b
1c
Ph
H
H
MeO2C
MeO2C
MeO2C
MeO2C
2
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgSbF6
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgOTf
1.5
2.5
90
89
2c
3b
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgNTf2
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgNTf2
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgNTf2
4.5
16
56
70
MeO2C
MeO2C
MeO2C
MeO2C
2d
2e
1d
O
4
TsN
TsN
O
1e
1f
Ph
H
H
5
6
2.5
53
TsN
O
TsN
Ph
O
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgSbF6
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgNTf2
72
72
SM
SM
/
O
MeO2C
MeO2C
2g
1g
1h
MeO2C
MeO2C
7
8
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgOTf
53
14
26b
O
MeO2C
MeO2C
2h
MeO2C
MeO2C
10 mol %mol %AuCl3, 10 mol %PPh3, 30 mol %AgOTf
10 mol %mol %AuCl3, 10 mol %PPh3, 30 mol %AgOTf
10 mol %AuCl3, 10 mol %PPh3, 30 mol %AgSbF6
42
O
2i
3
1i
1j
MeO2C
MeO2C
MeO2C
MeO2C
+
O
MeO2C
MeO2C
9
14
86
65
O
40:60
2j
O
H
O
Ph
H
H
H
2j’
Ph
10
1
Ph
O
+
O
O
86 : 14
a
Isolated yield.
60% conversion.
b
conditions at room temperature and isolated in 70% and 53% yields,
respectively. No reactivity was observed for aryl-substituted enyne
1f (Table 1, entry 6). The reaction of methyl-substituted prop-2-
enyl substrates 1g, 1h (Table 1, entries 7 and 8) was more sluggish,
with several unidentified by-products being observed. The ether
2g was isolated in 26% yield. In the case of crotyl-substituted deriv-
ative 1h, as previously reported,5c the reaction led selectively to
the six-membered ether 2h, which was obtained in 42% yield.

C.-M. Chao et al. / Tetrahedron Letters 50 (2009) 3719–3722
3721
SiMe3
H
Ph
H
Ph
O
O
H
H
H
AuCl3 (10 mol%)
PPh3 (10 mol%)
5 mol% Pd/C
H
MeO2C
MeO2C
H
H
O
MeO2C
MeO2C
Ph
E
E
O
E
E
Ph
Ph
E
+
H2 (1atm)
MeOH, rt, 16 h
60%
AgSbF6 (30 mol%)
rt, 22 h
H
E
H
7b
8
4 25%
5 19%
1b
E = CO2Me
dioxane/
NOESY
SiMe3
K2CO3, MeOH
43%
Ar
H
Ar
H
HO
H
H
5 equiv.
5 mol% Pd/C
O
O
O
O
5
H2 (1atm)
MeOH, rt, 2 h
97%
H
H
Scheme 2.
7e
9
Ar =
The allyloxycyclization reaction of 1,7-enyne 1i afforded the de-
sired ether in a modest 33% yield, the major product 3 resulting
from the formal hydration of the alkyne moiety (Table 1, entry
9). We also prepared a chiral 1,6-enyne 1j starting from commer-
cially available (R)-but-1-yn-3-ol via a classical Williamson reac-
tion. We were pleased to find that the tandem addition/
cyclization smoothly occurred and led to the formation of two dia-
stereomers 2j and 2j0 in 65% yield and in a 86/14 ratio. The stereo-
chemistry of the major isomer was determined by NMR NOESY
experiment.
O
O
Scheme 3.
We also examined the possibility of introduction of propargylic
alcohol, which would potentially allow an enyne metathesis pro-
cess. The addition of propargylic alcohol to the enyne 1b gave rise
to the degradation of the starting material, either in the presence of
allylic alcohol as the solvent or in a 6:1 mixture of dioxane/propar-
gylic alcohol. The introduction of trimethylsilylpropargylic alcohol
was successful and led to a mixture of 4 and 5 in 44% overall yield
(Scheme 2). This mixture was directly engaged in a desilylation
process under classical conditions, which afforded 4 in 43% yield.
Other attempts to introduce trimethylsilylpropargylic alcohol on
enynes 1a or 1e unfortunately did not give the desired products.
Our efforts next focused on the Ru-catalyzed metathesis reac-
tion of the cyclopentanyldienes 2 in the presence of Grubbs II cat-
alyst (2 or 4 mol %).4 The carbo- and heterocyclic ethers 2c and 2d
reacted smoothly in the presence of 4 mol % of Grubbs II catalyst
and the expected alkenes 6c and 6d were isolated in 64% yield (Ta-
ble 2, entries 1 and 2). The reactivity of 2e was particularly inter-
esting as an isomerized derivative 7e was isolated in 40% yield
(Table 2, entry 3). The diastereoselectivity of this isomerization
was further demonstrated after the hydrogenation reaction step
on derivative 9. Ru-catalyzed isomerization of olefins has been re-
cently highlighted and was firstly described by Nishida, Cossy, and
Alcaide groups in the presence of Grubbs II catalyst.10
The 6e/7e ratio was showed to depend on the catalyst loading.
The use of 2 mol % of catalyst led to a quasi equimolar quantity of
alkenes 6e and 7e (Table 2, entry 3). The reactivity of enyne 1b fol-
lowed the same trend (Table 2, entries 4 and 5). The completely
isomerized derivative 7b was isolated in 99% yield in the presence
of 4 mol %catalyst (Table 2, entry 4), whereas a 80:20 6b/7b mix-
ture was obtained in the presence of 2 mol %of Grubbs II catalyst
(Table 2, entry 5). The ring-closing metathesis of 2g was also suc-
cessful and afforded the tetrahydro-1H,3H-isochromene derivative
6g in 80% yield (Table 2, entry 6). The enyne metathesis was at-
tempted on substrate 5, no conversion was observed after 102 h.
We then envisaged synthesizing completely saturated 5/6 bicy-
clic derivatives via the catalytic hydrogenation of the alkene moi-
ety (Scheme 3). The classical hydrogenation of 7b and 7e,
conducted in the presence of 5 mol %Pd/C in methanol at room
temperature under 1 atm pressure H2 afforded the corresponding
bicyclic adducts 8 and 9 in 60% and 97% yields, respectively. The
diastereoselectivity of the tandem gold-catalyzed reaction and
the Ru-catalyzed ring-closing metathesis/isomerization process
was fully demonstrated at this stage by NMR NOESY experiment
on compound 9.
Table 2
Ruthenium-catalyzed metathesis reaction of dienes 2b–g
R1
R1 R2
O
R2
O
O
Grubbs II catalyst
CH2Cl2, reflux
H
H
R2
R1
H
Z
+
Z
Z
16-22 h
H
2b-g
6
7
Conditions: A 4 mol% cat., B 2 mol% cat.
Entry
1
2
Cond.
A
Products
Yielda (%)
64
MeO2C
MeO2C
O
2c
6c
O
+
2
3
2d
2e
A
64
TsN
6d
Ar
Ar
H
H
H
H
O
O
O
O
A
B
76
74
H
6e : 7e (1:4)
6e : 7e (46:54)
Ph
H
H
MeO2C
MeO2C
O
4
5
2b
A
99
H
7b
Ph
Ph
H
H
H
H
E
E
E
O
O
+
2b
2g
B
A
E
99
80
H
E = CO2Me
6b : 7b (79:21)
MeO2C
MeO2C
O
6
In conclusion, we have developed a sequential catalytic prepa-
ration of polycyclic heterocycles based on a gold-catalyzed cyclo-
isomerization reaction followed by a Ru-catalyzed ring-closing
6g
a
Isolated yield. Ar = 2,3-(CH2OCH2)–C6H3

3722
C.-M. Chao et al. / Tetrahedron Letters 50 (2009) 3719–3722
4. (a) Schwab, P.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1996, 118, 100;
(b) Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett. 1999, 1, 953;
(c) Garber, S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem.
Soc. 2000, 122, 8168.
metathesis, leading efficiently to tetrahydro furo- or cyclopenta-
pyran, hexahydropyrano pyrrolidine and tetrahydroisochromene
skeletons. The second catalytic step was accompanied in some
cases with an isomerization of the alkene moiety leading diastere-
oselectively to cis tetrahydrocyclopenta[c]pyran and tetrahydro-
1H-furo[3,4-c]pyran. The catalytic hydrogenation reactions of
these tetrahydropyrans led to the formation of polycyclic-function-
alized saturated compounds.
5. (a) Nevado, C.; Charruault, L.; Michelet, V.; Nieto-Oberhuber, C.; Muñoz, M. P.;
Méndez, M.; Rager, M.-N.; Genêt, J.-P.; Echavarren, A. M. Eur. J. Org. Chem. 2003,
706; (b) Charruault, L.; Michelet, V.; Taras, R.; Gladiali, S.; Genêt, J.-P. Chem.
Comm. 2004, 850; (c) Genin, E.; Leseurre, L.; Toullec, P. Y.; Genêt, J.-P.; Michelet,
V. Synlett 2007, 1780; (d) Leseurre, L.; Toullec, P. Y.; Genêt, J.-P.; Michelet, V.
Org. Lett. 2007, 9, 4049; (e) Genin, E.; Toullec, P. Y.; Antoniotti, S.; Brancour, C.;
Genêt, J.-P.; Michelet, V. J. Am. Chem. Soc. 2006, 128, 3112; (f) Genin, E.;
Antoniotti, S.; Michelet, V.; Genêt, J.-P. Angew. Chem., Int. Ed. 2005, 44, 4949; (g)
Antoniotti, S.; Genin, E.; Michelet, V.; Genêt, J.-P. J. Am. Chem. Soc. 2005, 127,
9976; (h) Genin, E.; Toullec, P. Y.; Marie, P.; Antoniotti, S.; Brancour, C.; Genêt,
J.-P.; Michelet, V. Arkivoc 2007, v, 67; (i) Neatu, F.; Li, Z.; Richards, R.; Toullec, P.
Y.; Genêt, J.-P.; Dumbuya, K.; Gottfried, J. M.; Steinrück, H.-P.; Pârvulescu, V. I.;
Michelet, V. Chem. Eur. J. 2008, 14, 9412; (j) Chao, C.-M.; Genin, E.; Toullec, P. Y.;
Genêt, J.-P.; Michelet, V. J. Organomet. Chem. 2008, 694, 538; (k) Toullec, P. Y.;
Chao, C.-M.; Chen, Q.; Genêt, J.-P.; Michelet, V. Adv. Synth. Catal. 2008, 250,
2401; (l) Toullec, P. Y.; Genin, E.; Leseurre, L.; Genêt, J.-P.; Michelet, V. Angew.
Chem., Int. Ed. 2006, 45, 7427; (m) Chao, C.-M.; Vitale, M. R.; Toullec, P. Y.;
Genêt, J.-P.; Michelet, V. Chem. Eur. J. 2009, 15, 1319; (n) Leseurre, L.; Chao, C.-
M.; Seki, T.; Genin, E.; Toullec, P. Y.; Genêt, J.-P.; Michelet, V. Tetrahedron 2009,
doi:10.1016/j.tet.2008.11.105.
Acknowledgments
This project was supported by the Centre National de Recherche
Scientifique (CNRS) and the Ministère de l’Education et de la
Recherche. C.-M.C. thanks the Ministère de l’Education et de la
Recherche for a grant (2007–2009). The authors thank Dr. M. N.
Rager for NOESY NMR analysis of compounds 9, 2j, and 2j0.
Supplementary data
6. (a) Nevado, C.; Cárdenas, D. J.; Echavarren, A. M. Chem. Eur. J. 2003, 9, 2627; (b)
Martín-Matute, B.; Nevado, C.; Cárdenas, D. J.; Echavarren, A. M. J. Am. Chem.
Soc. 2003, 125, 5757; (c) Méndez, M.; Muñoz, M. P.; Nevado, C.; Cárdenas, D. J.;
Echavarren, A. M. J. Am. Chem. Soc. 2001, 123, 10511; (d) Méndez, M.; Muñoz,
M. P.; Echavarren, A. M. J. Am. Chem. Soc. 2000, 122, 11549; (e) Nishizawa, M.;
Yadav, V. K.; Skwarczynski, M.; Takao, H.; Imagawa, H.; Sugihara, T. Org. Lett.
2003, 5, 1609; (f) Nishizawa, M.; Imagawa, H. J. Synth. Org. Chem. Japan 2006,
64, 744; Faller, J. W.; Fontaine, P. P. J. Organomet. Chem. 2006, 691, 1912; (g)
Muñoz, M. P.; Adrio, J.; Carretero, J. C.; Echavarren, A. M. Organometallics 2005,
24, 1293; (h) Nieto-Oberhuber, C.; Lopez, S.; Echavarren, A. M. J. Am. Chem. Soc.
2005, 127, 6178; (i) Nieto-Oberhuber, C.; Muñoz, M. P.; Nevado, C.; Cárdenas, D.
J.; Echavarren, A. M. Angew. Chem., Int. Ed. 2004, 43, 2402; (j) Mézailles, N.;
Ricard, L.; Gagosz, F. Org. Lett. 2005, 7, 4133; (k) Nieto-Oberhuber, C.; Muñoz,
M. P.; Lopez, S.; Jimenez-Nuñez, E.; Nevado, C.; Herrero-Gomez, E.; Raducan,
M.; Echavarren, A. M. Chem. Eur. J. 2006, 12, 1677; (l) Buzas, A. K.; Istrate, F. M.;
Gagosz, F. Angew. Chem., Int. Ed. 2007, 46, 1141; (m) Zhang, L.; Kozmin, S. A. J.
Am. Chem. Soc. 2005, 127, 6962–6963; (n) Cabello, N.; Rodriguez, C.;
Echavarren, A. M. Synlett 2007, 1753.
7. (a) Durst, G. L.; Norman, B. H.; Pfeifer, L. A.; Richardson, T. I. PCT Int. Appl. 2004,
WO 2004094400.; (b) Norman, B. H.; Richardson, T. I. PCT Int. Appl. 2006, WO
2006044176.; (c) Ratnayake, R.; Covell, D.; Ransom, T. T.; Gustafson, K. R.;
Beutler, J. A. Org. Lett. 2008, 10, 57; (d) Jimenez-Alonso, S.; Perez-Lomas, A.;
Estevez-Braun, A.; Munoz Martinez, F.; Chavez Orellana, H.; Ravelo, A. G.;
Gamarro, F.; Castanys, S.; Lopez, M. J. Med. Chem. 2008, 51, 7132; (e) Wang, H.-
X.; Liu, C.-M.; Liu, Q.; Gao, K. Phytochemistry 2008, 69, 2088; (f) Korthals, K. A.;
Wulff, W. D. J. Am. Chem. Soc. 2008, 130, 2898; (g) Richardson, T. I.; Dodge, J. A.;
Wang, Y.; Durbin, J. D.; Krishnan, V.; Norman, B. H. Bioorg. Med. Chem. Lett.
2007, 17, 5563. and references cited therein; (h) Barlow, A. J.; Compton, B. J.;
Hertewich, U.; Lorimer, S. D.; Weavers, R. T. J. Nat. Prod. 2005, 68, 825; (i) Zheng,
Y.; Shen, Y. Org. Lett. 2009, 11, 109.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2009.04.001.
References and notes
1. (a) Cornils, B.; Herrmann, W. A. Applied Homogeneous Catalysis with
Organometallic Compound; VCH: New-York, 1996; (b) Trost, B. M. Acc. Chem.
Res. 2002, 35, 695; (c) Trost, B. M. Angew.Chem., Int. Ed. Engl. 1995, 34, 259; (d)
Trost, B. M. Science 1991, 254, 1471; (e) Anastas, P.; Warner, J. C. Green
Chemistry, Theory and Practice; Oxford University Press, 1998; (f) Anastas, P. T.;
Kirchhoff, M. M. Acc. Chem. Res. 2002, 35, 686; (g) Anastas, P. T.; Zimmerman, J.
B. Environ. Sci. Technol. 2003, 37, 94A; (h) Poliakoff, M.; Fitzpatrick, J. M.; Farren,
T. R.; Anastas, P. T. Science 2002, 297, 807; (i) Trost, B. M.; Toste, D. F.; Pinkerton,
A. B. Chem. Rev. 2001, 101, 2067.
2. (a) Arcadi, A. Chem. Rev. 2008, 108, 3266; (b) Patil, N. T.; Yamamoto, Y. Chem.
Rev. 2008, 108, 3395; (c) Li, Z.; Brouwer, C.; He, C. Chem. Rev. 2008, 108, 3239;
(d) Shen, H. C. Tetrahedron 2008, 64, 3885; (e) Skouta, R.; Li, C.-J. Tetrahedron
2008, 64, 4917; (f) Hashmi, A. S. K.; Rudolph, M. Chem. Soc. Rev. 2008, 37, 1766;
(g) Muzart, J. Tetrahedron 2008, 64, 5815; (h) Hashmi, A. S. K. Chem. Rev. 2007,
107, 3180; (i) Gorin, D. J.; Toste, D. Nature 2007, 446, 395; (j) Hashmi, A. S. K.;
Hutchings, G. J. Angew Chem., Int. Ed. 2006, 45, 7896; (k) Jimenez-Nunez, E.;
Echavarren, A. M. Chem. Commun. 2007, 333; (l) Ma, S.; Yu, S.; Gu, Z. Angew.
Chem., Int. Ed. 2006, 45, 200; (m) Hashmi, A. S. K. Angew. Chem., Int. Ed. 2005, 44,
6090; (n) Höffmann-Röder, A.; Krause, N. Org. Biomol. Chem. 2005, 3, 387.
3. (a)For selected reviews on Ru-catalyzed reactions: Hand Book of Metathesis;
Grubbs, R. H., Ed.; Wiley-VCH: Weinheim, 2003; Vols. 1–3, (b) Kotha, S.;
Mandal, K. Chem. Asian J. 2009. 10.1002/asia.200800244; (c) Grubbs, R. H.
Tetrahedron 2004, 60, 7117; (d) McReynolds, M. D.; Dougherty, J. M.; Hanson, P.
R. Chem. Rev. 2004, 104, 2239; (e) Nakamura, I.; Yamamoto, Y. Chem. Rev. 2004,
104, 2127–2198; (f) Deiters, A.; Martin, S. F. Chem. Rev. 2004, 104, 2199; (g)
Diver, S. T.; Giessert, A. J. Chem. Rev. 2004, 104, 1317; (h) Villar, H.; Frings, M.;
Bolm, C. Chem. Soc. Rev. 2007, 55; (i) Sémeril, D.; Bruneau, C.; Dixneuf, P. H. Adv.
Synth. Catal. 2002, 344, 585; (j) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew.
Chem., Int. Ed. 2005, 44, 4490; (k) Kotha, S.; Lahiri, K. Synlett 2007, 2767; (l)
Trost, B. M.; Frederiksen, M. U.; Rudd, M. T. Angew. Chem., Int. Ed. 2005, 44,
6630; (m) Naota, T.; Takaya, H.; Murahashi, S.-I. Chem. Rev. 1998, 98, 2599.
8. (a) Amijs, C. H. M.; Lopez-Carrillo, V.; Raducan, M.; Perez-Galan, P.; Ferrer, C.;
Echavarren, A. M. J. Org. Chem. 2008, 73, 7721; (b) 6l
9. Dr. E. Genin, Dissertation from the University Pierre et Marie Curie, 2006.
10. For leading references, see: (a) Donohoe, T. J.; O’Riordan, T. J. C.; Rosa, C. P.
Angew. Chem. Int. Ed. 2009, 48, 1014; (b) Alcaide, B.; Almendros, P.; Alonso, J. M.
Org. Lett. 2001, 3, 3781; (c) Arisawa, M.; Terada, Y.; Nakagawa, M.; Nishida, A.
Angew. Chem., Int. Ed. 2002, 41, 4732; (d) Cadot, C.; Dalko, P. I.; Cossy, J.
Tetrahedron Lett. 2002, 43, 1839.