Rhodium-catalyzed highly stereoselective hydroselenation of internal alkynes bearing an electron-withdrawing group

Article abstract of DOI:10.1021/om200663k

Rhodium-catalyzed highly regio- and stereoselective hydroselenation of internal alkynes bearing an electron-withdrawing group took place to give (E)-vinyl selenides in good yields. The excellent syn stereoselectivity of this rhodium-catalyzed hydroselenation is of great importance in terms of complementing the previously reported hydroselenation of alkynes.

Full text of DOI:10.1021/om200663k

Note
pubs.acs.org/Organometallics
Rhodium-Catalyzed Highly Stereoselective Hydroselenation of
Internal Alkynes Bearing an Electron-withdrawing Group
Shin-ichi Kawaguchi, Mao Kotani, Shingo Atobe, Akihiro Nomoto, Motohiro Sonoda, and Akiya Ogawa*
Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai,
Osaka 599-8531, Japan
S
* Supporting Information
ABSTRACT: Rhodium-catalyzed highly regio- and stereo-
selective hydroselenation of internal alkynes bearing an
electron-withdrawing group took place to give (E)-vinyl
selenides in good yields. The excellent syn stereoselectivity
of this rhodium-catalyzed hydroselenation is of great
importance in terms of complementing the previously reported
hydroselenation of alkynes.
INTRODUCTION
RESULTS AND DISCUSSION
■
■
Organoselenium compounds are widely used as synthetic
intermediates and biologically active compounds.1 Among
them, vinyl selenides are employed as synthetic equivalents of
vinyl groups as well as carbonyl groups, because they can be
easily converted to a variety of vinyl derivatives.2 Addition of
selenols to alkynes is one of the most straightforward methods
for synthesis of vinyl selenides.3 It has been reported that
hydroselenation of alkynes proceeds via ionic pathways,4 radical
pathways,4c,d,5 or transition-metal-catalyzed pathways.6 It is
important to control regio- and stereoselectivities of hydro-
selenation of alkynes, especially internal alkynes. In general,
ionic additions of selenols to internal alkynes give anti-adducts
preferentially (Scheme 1, eq 1).4 Although transition-metal-
First, we investigated the hydroselenation of 1-phosphinyl-1-
octyne with benzeneselenol varying the catalysts under several
conditions (Table 1). When the hydroselenation was conducted
in the absence of both transition metal catalyst and additive,
small amounts of Michael-type adduct were obtained with low
stereoselectivity (entry 1). Addition of Et3N increased the yield
of the Michael-type adduct, but the stereoselectivity was still not
improved (entry 2). Next, we attempted the hydroselenation
using several palladium catalysts, but the hydroselenation did
not proceed (entries 4, 6, and 7). However, Wilkinson’s catalyst
exhibited excellent catalytic activity toward the regio- and stereo-
selective hydroselenation (entry 8). Interestingly, Wilkinson’s
catalyst with a catalytic amount of Ph2P(O)H attained high yield
and excellent selectivity, as shown in entry 10.
Table 2 represents the results of RhCl(PPh3)3-catalyzed
hydroselenation of several internal alkynes. Hydroselenation of
internal alkynes bearing phenyl, ester, or carbonyl groups pro-
ceeded successfully, and the corresponding (E)-alkenyl
selenides were obtained stereoselectively in good to excellent
yields (entries 1−5). Moreover, several phosphinyl-substituted
internal alkynes underwent hydroselenation, and both
phosphinyl- and seleno-substituted alkenes 3g and 3h were
obtained with excellent regio- and stereoselectivities (entries 7
and 8).8,9 In this system, curiously, hydrophosphinylation of
alkynes did not take place at all. In the case of terminal alkynes
such as 1-dodecyne, unfortunately, selective hydroselenation
did not take place successfully under the present conditions.
This reaction afforded a complex mixture involving Markovni-
kov adduct (nC10H21-C(SePh)CH2, 31%) as a major adduct.
To gain insight into the role of Ph2P(O)H, we monitored the
reaction of PhSeH with Ph2P(O)H (δ 18.0 ppm, in C6D6) by
31P NMR. When PhSeH was mixed with Ph2P(O)H in the
presence of RhCl(PPh3)3 catalyst in C6D6, the formation of
Scheme 1
catalyzed reactions often exhibit excellent selectivity, only very
limited examples of transition-metal-catalyzed hydroselenations
of internal alkynes have been reported.7 Herein we report a
highly regio- and stereoselective hydroselenation of selenols to
internal alkynes with electron-withdrawing groups by using a
novel RhCl(PPh3)3-Ph2P(O)H catalytic system. This hydro-
selenation exhibits excellent syn-selectivity (Scheme 1, eq 2).
Received: July 22, 2011
Published: December 2, 2011
© 2011 American Chemical Society
6766
dx.doi.org/10.1021/om200663k | Organometallics 2011, 30, 6766−6769

Organometallics
Note
Table 1. Optimization of Hydroselenation of 1-Phosphinyl-1-octyne
a
entry
catalyst
none
additive
time (h)
yield
1
2
3
4
5
6
7
8
9
10
none
2
2
17% (E/Z = 59/41)
70% (E/Z = 40/60)
39% (E/Z = 28/72)
trace
none
Et3N 3 equiv
Ph2P(O)H 10 mol%
none
none
2
PdCl2(PPh3)2
PdCl2(PPh3)2
Pd(PPh3)4
PdCl2(cod)2
RhCl(PPh3)3
RhCl(PPh3)3
RhCl(PPh3)3
15
2
Et3N 3 equiv
none
70% (E/Z = 44/56)
0%
15
15
2
none
0%
none
46% (E/Z = 100/0)
8% (E/Z = 100/0)
84% (E/Z = 100/0)
Et3N 3 equiv
Ph2P(O)H 10 mol%
15
2
a
1
Determined by H NMR.
Table 2. Hydroselenation of Internal Alkynes Bearing an
Electron-Withdrawing Group
of terminal alkynes with PhSeH in the presence of Pd or Pt
catalysts.6b In the literature, it is described that dehydrogenative
coupling of PhSeH occurred to generate (PhSe)2 in the system
(Scheme 2, eq 4). We investigated the reaction of PhSeH in
the presence of a catalytic amount of RhCl(PPh3)3 (eq 5). In a
similar way, a dehydrogenative coupling reaction of PhSeH
took place smoothly to afford (PhSe)2 with evolution of H2.12
In sharp contrast, in the copresence of catalytic amounts
of RhCl(PPh3)3 and Ph2P(O)H, most PhSeH was unchanged
except for the formation of Ph2P(O)SePh from PhSeH and
Ph2P(O)H (eq 6). This clearly indicates that Ph2P(O)SePh
suppresses Rh-catalyzed dehydrogenative coupling of PhSeH.
When (PhSe)2 and Ph2P(O)H were mixed, Ph2P(O)SePh and
PhSeH were immediately formed (eq 7). We assume that this
process results in depression of side reactions. Indeed, when
(PhSe)2 and an equimolar amount of Ph2P(O)H were employed
for the Rh-catalyzed reaction of alkynes such as 1a, hydroselenation
took place successfully with excellent regio- and stereoselectivities
(eq 8).
On the basis of these mechanistic experiments, a possible
reaction pathway is proposed, as shown in Scheme 3. In the
present RhCl(PPh3)3-Ph2P(O)H system, PhSeH reacts imme-
diately with Ph2P(O)H to form Ph2P(O)SePh (4), which adds
oxidatively to Rh(I) species to generate rhodium intermediate
5. This species 5 adds to an alkyne to give vinylrhodium inter-
mediate 6. The subsequent protonation of vinylrhodium inter-
mediate 6 with PhSeH leads to syn-adduct 3 with regeneration
of rhodium species 5.13,14
CONCLUSION
■
a
b
1
We have developed a rhodium-catalyzed, highly regio- and
stereoselective hydroselenation of internal alkynes bearing
electron-withdrawing groups. It has been found that addition
of a catalytic amount of Ph2P(O)H can control the desired
rhodium-catalyzed hydroselenation.
Determined by H NMR. Isolated yield.
Ph2P(O)SePh (4) was observed (δ 37.3 ppm) (eq 3).10
Although Ph2P(O)H is known to behave as a bidentate ligand,11
in this hydroselenation, Ph2P(O)H preferentially converts to
Ph2P(O)SePh, which plays an important role in this system.
EXPERIMENTAL SECTION
■
General Comments. Internal alkynes 1a,15 1d,16 1e,16 1f,17 1g,15
and 1h15 were synthesized according to the literature. Other materials
were obtained as commercial supplies. Benzene was purified by
distillation before use. Other materials were used without further
purification. The synthetic methods of compounds 3b4d and 3c4i are
described in the literature.
(3)
On the other hand, PhSeH can be converted to (PhSe)2 in the
presence of a transition-metal catalyst. Ananikov and Beletskaya
et al. have clarified the mechanism of the hydroselenation
6767
dx.doi.org/10.1021/om200663k | Organometallics 2011, 30, 6766−6769

Organometallics
Note
Scheme 2
Scheme 3
(m, 15H); 13C NMR (CDCl3) δ 13.8, 22.3, 27.7, 29.0, 31.2, 40.2,
118.3 (d, JC−P = 108.2 Hz), 128.4 (d, JC−P = 12.4 Hz), 128.6, 128.9,
131.0 (d, JC−P = 9.9 Hz), 131.4, 132.0, 133.7 (d, JC−P = 105.7 Hz),
136.4, 163.3; 31P NMR (CDCl3) δ 22.6; HRMS (FAB) calcd for
[M + H+] C26H29OPSe 469.1199, found 469.1222.
1
(E)-1-Benzoyl-2-(phenylseleno)-1-octene (3d): yellow oil; H
NMR (CDCl3) δ 0.80 (t, J = 7.1 Hz, 3H), 0.96−1.45 (m, 8H), 2.35 (t,
J = 7.8 Hz, 2H), 7.24 (s, 1H), 7.34−7.52 (m, 6H), 7.69 (d, J = 6.9 Hz,
2H), 8.01 (d, J = 6.8 Hz, 2H);13C NMR (CDCl3) δ 14.1, 22.6, 28.7,
30.6, 31.4, 38.6, 118.0, 128.2, 128.7, 129.2, 130.0, 131.6, 132.3, 137.4,
138.5, 169.3, 189.0; MS (EI), m/z (%) = 372 (M+, 1), 215 (M+ −
SePh, 19); HRMS (EI) calcd for C21H24OSe 372.0992, found
372.0992.
1
(E)-1-Benzoyl-2-(phenylseleno)-1-hexene (3e): yellow oil; H
NMR (CDCl3) δ 0.69 (t, J = 7.3 Hz, 3H), 1.07 (sextet, J = 7.3 Hz,
2H), 1.40 (quin, J = 7.6 Hz, 2H), 2.36 (t, J = 7.8 Hz, 2H), 7.32−7.54
(m, 7H), 7.70 (d, J = 8.2 Hz, 2H), 8.01 (d, J = 6.9 Hz, 2H); 13C NMR
(CDCl3) δ 13.6, 22.1, 32.7, 38.3, 118.0, 128.2, 128.7, 128.8, 129.16,
129.22, 132.3, 137.4, 138.5, 169.2, 189.0; MS (EI), m/z (%) = 344
(M+, 2), 187 (M+ − SePh, 49); HRMS (EI) calcd for C19H20OSe
344.0679, found 344.0685.
(E)-4-(Phenylseleno)-tetradec-3-en-2-one (3f): pale yellow oil;
General Procedure for Hydroselenation of Benzeneselenol
to Internal Alkynes. In a 20 mL two-necked flask equipped with a
reflux condenser were placed alkyne 1 (0.1 mmol) and PhSeH (18.9
mg, 0.12 mmol) together with RhCl(PPh3)3 (4.6 mg, 0.005 mmol),
Ph2P(O)H (2.0 mg, 0.01 mmol), and benzene (2 mL) under a
nitrogen atmosphere. The resulting red-brown mixture was heteroge-
neous with a small precipitate, and it was heated at 80 °C for 2 h.
During the reaction, the precipitate that came from the Rh catalyst was
observed. After the reaction was complete, the mixture was filtrated
through a Celite pad, the precipitate was removed by using
chloroform, and then the filtrate was concentrated under reduced
pressure. The crude mixture was purified by preparative TLC (eluent:
hexane/AcOEt) to give vinyl selenide 3. Compounds 3d, 3e, and 3f
were obtained as an E/Z mixture. Before isolation, E/Z ratios were
unchanged. In the cases of 3a, 3c, 3g, and 3h, the formation of only
E-isomers was observed in the crude mixture. The E/Z ratios were
1H NMR (CDCl3) (E-isomer) δ 0.88 (t, J = 6.9 Hz, 3H), 1.21−1.34
(m, 14H), 1.56−1.64 (m, 2H), 2.19 (t, J = 7.8 Hz, 2H), 2.25 (s, 3H),
6.67 (s, 1H), 7.25−7.42 (m, 5H); 13C NMR (CDCl3) δ 14.2, 22.8,
29.1, 29.3, 29.4, 29.5, 29.6, 29.7, 30.3, 31.9, 37.9, 121.5, 127.8, 129.1,
135.4, 137.4, 165.7, 196.7; MS (EI), m/z (%) = 366 (M+, 2), 209
(M+ − SePh, 20).
(E)-1-(Diphenylphosphinyl)-5-methyl-2-(phenylseleno)-1-
hexene (3g): yellow oil; 1H NMR (CDCl3) (E-isomer) δ 0.73 (d, J =
6.4 Hz, 6H), 1.32−1.42 (m, 3H), 2.81 (dt, JH−P,H−H = 1.4, 7.3 Hz, 2H),
5.81 (d, JH−P = 21.5 Hz, 1H), 7.24−7.51 (m, 9H), 7.54−7.65 (m, 6H);
13C NMR (CDCl3) δ 22.3, 28.1, 29.7, 34.1 (d, JC−P = 7.7 Hz), 115.8
(d, JC−P = 99.7 Hz), 127.6, 128.5 (d, JC−P = 12.5 Hz), 129.4, 129.8,
130.8 (d, JC−P = 9.6 Hz), 131.5 (d, JC−P = 2.9 Hz), 134.9 (d, JC−P
=
104.5 Hz), 137.0, 166.1; 31P NMR (CDCl3) δ 19.6 ppm; HRMS
(FAB) calcd for [M + H+] C25H27OPSe 455.1043, found 455.1017.
(E)-2-(Diphenylphosphinyl)-1-(phenylseleno)-1-phenyl-
ethene (3h): yellow oil; 1H NMR (CDCl3) (E-isomer) δ 6.12
(d, JH−P = 16.0 Hz, 1H), 7.15−7.71 (m, 20H); 13C NMR (CDCl3)
δ 116.9 (d, JC−P = 102.2 Hz), 127.6, 128.5 (d, JC−P = 12.1 Hz), 128.7,
129.4, 129.8, 130.8 (d, JC−P = 10.2 Hz), 130.9, 131.5, 132.2, 132.9,
1
determined by H NMR.
Spectral and Analytical Data. (E)-1-(Diphenylphosphinyl)-2-
1
(phenylseleno)-1-octene (3a): pale yellow oil; H NMR (CDCl3)
δ 0.80 (t, J = 7.3 Hz, 3H), 1.05−1.23 (m, 6H), 1.41−1.52 (m, 2H),
2.80 (t, J = 7.8 Hz, 2H), 5.77 (d, JH−P = 21.6 Hz, 1H), 7.21−7.69
6768
dx.doi.org/10.1021/om200663k | Organometallics 2011, 30, 6766−6769

Organometallics
Note
134.9 (d, JC−P = 101.4 Hz), 137.2, 166.8; 31P NMR (CDCl3) δ 19.2
ppm; HRMS (EI) calcd for C26H21OPSe 460.0496, found 460.0488.
Reaction of Benzeneselenol with Diphenylphosphine Oxide
in the Presence of RhCl(PPh3)3 Catalyst. In an NMR tube,
Ph2P(O)H (60.7 mg, 0.30 mmol), PhSeH (47.1 mg, 0.30 mmol), and
RhCl(PPh3)3 (13.9 mg, 0.015 mmol) were placed with C6D6 (0.6 mL)
under a nitrogen atmosphere. The mixture was heated at 80 °C for 2 h.
During heating, evolution of gas was observed. After the reaction, the
formation of Ph2P(O)SePh was determined by 1H, 31P, and 77Se NMR
spectroscopies. The yield of Ph2P(O)SePh (97%) was determined by
1H NMR spectroscopy in C6D6 with 1,3,5-trioxane as internal
Chem. USSR (Engl. Transl.) 1984, 1897. (f) Renard, M.; Hevesi, L.
Tetrahedron 1985, 41, 5939. (g) Comasseto, J. V.; Brandt, C. A.
Synthesis 1987, 146. (h) Barros, O. S. D.; Lang, E. S.; de Oliveira,
C. A. F.; Peppe, C.; Zeni, G. Tetrahedron Lett. 2002, 43, 7921.
(i) Perin, G.; Jacob, R. G.; de Azambuja, F.; Botteselle, G. V.; Siqueira,
G. M.; Freitag, R. A.; Lenardao, E. J. Tetrahedron Lett. 2005, 46, 1679.
(j) Lenardao, E. J.; Silva, M. S.; Mendes, S. R; de Azambuja, F.; Jacob,
R. G.; dos Santos, P. C. S.; Perin, G. J. Braz. Chem. Soc. 2007, 18, 943.
(5) (a) Ogawa, A.; Obayashi, R.; Sekiguchi, M.; Masawaki, T.;
Kambe, N.; Sonoda, N. Tetrahedron Lett. 1992, 33, 1329.
(6) (a) Kuniyasu, H.; Ogawa, A.; Sato, K.; Ryu, I.; Sonoda, N.
Tetrahedron Lett. 1992, 33, 5525. (b) Ananikov, V. P.; Malyshev, D. A.;
Beletskaya, I. P.; Aleksandrov, G. G.; Eremenko, I. L. J. Organomet.
Chem. 2003, 679, 162. (c) Kamiya, I.; Nishinaka, E.; Ogawa, A. J. Org.
Chem. 2005, 70, 696. (d) Ananikov, V. P.; Orlov, N. V.; Beletskaya,
I. P. Organometallics 2007, 26, 740. (e) Ozaki, T.; Kotani, M.; Kusano,
H.; Nomoto, A.; Ogawa, A. J. Organomet. Chem. 2011, 696, 450.
(7) Only one example of transition-metal-catalyzed hydroselenation
of internal alkynes with excellent stereoselectivity, to the best of our
knowledge, has been reported. See ref 6d.
(8) As to hydrothiolation of alkynylphosphines, Pd(OAc)2-catalyzed
anti-addition of thiol to alkynylphosphines has been reported, see:
Kondoh, A.; Yorimitsu, H.; Oshima, K. Org. Lett. 2007, 9, 1383.
(9) Regioisomers of 1-diphenylphosphinyl-2-phenylseleno-1-alkene
were described in the following literature: Kawaguchi, S-i.; Shirai, T.;
Ohe, T.; Nomoto, A.; Sonoda, M.; Ogawa, A. J. Org. Chem. 2009, 74,
1751.
(10) There are some reports of transition-metal-catalyzed dehydro-
genative coupling reactions of E−H compounds. For example, see:
(a) Ishiyama, T.; Nishijima, K-i.; Miyaura, N.; Suzuki, A. J. Am. Chem.
Soc. 1993, 115, 7225. (b) Clark, T. J.; Lee, K.; Manners, I. Chem.Eur.
J. 2006, 12, 8634. (c) Itazaki, M.; Ueda, K.; Nakazawa, H. Angew.
Chem., Int. Ed. 2009, 48, 3313. (d) Less, R. J.; Melen, R. L.; Naseri, V.;
Wright, D. S. Chem. Commun. 2009, 4929.
1
standard. Spectral data of Ph2P(O)SePh: H NMR (C6D6) δ 6.75−
6.79 (m, 3H), 6.87−6.93 (m, 6H), 7.58−7.65 (m, 2H), 7.82−7.89 (m,
4H); 31P NMR (C6D6) δ 37.3 ppm (with 2 satellites JP−Se = 372 Hz);
77Se NMR δ 377 ppm (d, JSe−P = 372 Hz).
Reaction of Diphenyl Diselenide with Diphenylphosphine
Oxide. In an NMR tube, Ph2P(O)H (101.1 mg, 0.50 mmol), (PhSe)2
(156.1 mg, 0.50 mmol), and C6D6 (1 mL) were placed under a
nitrogen atmosphere. The mixture was stirred for 5 min at room
temperature, and then NMR spectra of the crude mixture were
measured. The charts of 31P and 77Se NMR spectroscopies indicated
that Ph2P(O)H (δ 18.0 ppm in C6D6)18 and (PhSe)2 (δ 461 ppm in
C6D6)19 were consumed completely. In the crude mixture, 90% yield
of PhSeH (δ 143 ppm in C6D6)19 and 92% yield of Ph2P(O)SePh
1
were formed, respectively. These yields were determined by H NMR
spectroscopy.
ASSOCIATED CONTENT
* Supporting Information
■
S
Information about a determination of stereoselectivity for 3.
This material is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*Tel and Fax: +81-72-254-9290. E-mail: ogawa@chem.osakafu-
u.ac.jp.
(11) Ackermann, L. Synthesis 2006, 10, 1557.
■
(12) Addition of Et3N promoted Rh-catalyzed dehydrogenative
coupling of PhSeH. Therefore, the yield of 3a in the case of entry 9 in
Table 1 was low.
(13) In this system, both phosphinyl- and seleno-substituted alkene was
not obtained. For Pd-catalyzed selenophosphorylation of alkynes, see:
Han, L.-B.; Choi, N.; Tanaka, M. J. Am. Chem. Soc. 1996, 118, 7000.
(14) We have found a similar type of ligand exchange reaction of
(RR′CCH)Rh-P(O)Ph2 or (RR′CCH)Pd-P(O)Ph2 species, see:
(a) Kawaguchi, S-i.; Kotani, M.; Ohe, T.; Nagata, S.; Nomoto, A.;
Sonoda, M.; Ogawa, A. Phosphorous Sulfur, Silicon, Relat. Elem. 2010,
185, 1090. (b) Kawaguchi, S-i.; Nagata, S.; Nomoto, A.; Sonoda, M.;
Ogawa, A. J. Org. Chem. 2008, 73, 7928.
ACKNOWLEDGMENTS
■
This work was supported by a Grant-in-Aid for JSPS Fellows
(No. 21-10516) from the Japan Society for the Promotion of
Science and by Industry-University Cooperation Program of
Sakai City.
REFERENCES
■
(15) Beletskaya, I. P.; Afanasiev, V. V.; Kazankova, M. A.; Efimova,
I. V. Org. Lett. 2003, 5, 4309.
(1) Selected representative reviews: (a) Klayman, D. L.; Gunther,
̈
W. H. H. Organic Selenium Compounds: Their Chemistry and Biology;
John Wiley & Sons: New York, 1973. (b) Wirth, T. Organoselenium
Chemistry; Springer: Berlin, 2000; Vol. 208. (c) Ogawa, A. In Main
Group Metals in Organic Synthesis; Yamamoto, H., Oshima, K., Eds.;
Wiley-VCH: Weinheim, 2004; Vol. 2, p 813. (d) Nogueira, C. W.;
Zeni, G.; Rocha, J. B. T. Chem. Rev. 2004, 104, 6255.
(2) (a) Rappoport, Z. The Chemistry of Organic Selenium and
Tellurium Compounds, Vol. 3; John Wiley & Sons: New York, in press.
(b) Tingoli, M.; Tiecco, M.; Testaferri, L.; Temperini, A.; Pelizzi, G.;
Bacchi, A. Tetrahedron 1995, 51, 4691. (c) Zhu, L.-S.; Huang, X. Synth.
Commun. 1997, 27, 39. (d) Fang, X.; Jiang, M.; Hu, R.; Cai, M. Synth.
Commun. 2008, 38, 4170.
(16) Tohda, Y.; Sonogashira, K.; Hagihara, N. Synthesis 1977, 777.
(17) Dos Santos, A. A.; Castelani, P.; Bassora, B. K.; Fogo, J. C.;
Costa, C. E.; Comasseto, J. V. Tetrahedron 2005, 61, 9173.
(18) Kawaguchi, S-i.; Nagata, S.; Shirai, T.; Tsuchii, K.; Nomoto, A.;
Ogawa, A. Tetrahedron Lett. 2006, 47, 3919.
(19) Crich, D.; Jiao, X.-Y.; Yao, Q.; Harwood, J. S. J. Org. Chem.
1996, 61, 2368.
(3) (a) Alonso, F.; Beletskaya, I. P.; Yus, M. Chem. Rev. 2004, 104,
3079. (b) Beletskaya, I. P.; Ananikov, V. P. Chem. Rev. 2011, 111,
1596.
(4) (a) Kataev, E. G.; Petrov, V. N. J. Gen. Chem. USSR (Engl.
Transl.) 1962, 32, 3626. (b) Petragnani, N.; Rodrigues, R.; Comasseto,
J. V. J. Organomet. Chem. 1976, 114, 281. (c) Wadsworth, D. H.; Detty,
M. R. J. Org. Chem. 1980, 45, 4611. (d) Comasseto, J. V.; Ferreira,
J. T. B.; Petragnani, N. J. Organomet. Chem. 1981, 216, 287. (e) Tsoi,
L. A.; Patsaev, A. K.; Ushanov, V. Zh.; Vyaznikovtsev, L. V. J. Org.
6769
dx.doi.org/10.1021/om200663k | Organometallics 2011, 30, 6766−6769