partner. The reaction involves the Rh-catalyzed regio-
selective insertion of an alkyne into an arylrhodium(I)
species and the oxidative addition of C–Br bonds in the
adjacent phenyl ring to the resulting vinylrhodium(I) species
as key steps. More importantly, the outcome of the deuterium
labelling experiment disclosed that a direct reductive elimination
mechanism dominates over the formation of aryl–Csp3
bonds from aryl-Rh(III)-Csp3 species. Further studies on the
application of the products and the reaction mechanism are
ongoing in our laboratories, and will be reported in
due course.
Notes and references
1 For reviews, see: (a) T. Miura and M. Murakami, Chem. Commun.,
2007, 217; (b) H. C. Guo and J. A. Ma, Angew. Chem., Int. Ed.,
2006, 45, 354; (c) J. C. Wasilke, S. J. Obrey, R. T. Baker and
G. C. Bazan, Chem. Rev., 2005, 105, 1001; (d) J. Montgomery,
Angew. Chem., Int. Ed., 2004, 43, 3890; (e) R. Grigg and
V. Sridharan, J. Organomet. Chem., 1999, 576, 65; (f) E. Negishi,
C. Coperet, S. Ma, S. Y. Liou and F. Liu, Chem. Rev., 1996, 96,
´
365; (g) L. F. Tietze, Chem. Rev., 1996, 96, 115.
2 For recent reviews, see: (a) T. Miura and M. Murakami, Chem.
Commun., 2007, 217; (b) S. W. Youn, Eur. J. Org. Chem., 2009, 16,
2597.
3 (a) R. Shintani, K. Okamoto and T. Hayashi, Chem. Lett., 2005,
34, 1294; (b) T. Matsuda, M. Makino and M. Murakami, Chem.
Lett., 2005, 34, 1416.
Scheme 3 A proposal for the outcome of eqn (2).
as the cis-configuration on the basis of 1H NMR analysis
(see the ESIw).
4 M. Lautens and T. Marquardt, J. Org. Chem., 2004, 69, 4607.
5 M. Miyamoto and N. Chatani, Org. Lett., 2008, 10, 2975.
6 T. Miura and M. Murakami, Org. Lett., 2005, 7, 3339.
7 (a) Y. Harada and N. Chatani, J. Am. Chem. Soc., 2007, 129, 5766;
(b) T. Morimoto and N. Chatani, Org. Lett., 2009, 11, 1777.
8 For reviews, see: (a) A. M. Echavarren and C. Nevado, Chem. Soc.
Rev., 2004, 33, 431; (b) C. Aubert, O. Buisine and M. Malacria,
Chem. Rev., 2002, 102, 813; (c) B. M. Trost, F. D. Toste and
A. B. Pinkerton, Chem. Rev., 2001, 101, 2067.
ð2Þ
9 For the synthesis and utility of similar dihydronaphthalene
derivatives, see: (a) G. Dyker, D. Hildebrandt, J. Liu and
K. Merz, Angew. Chem., Int. Ed., 2003, 42, 4399; (b) N. Asao,
T. Kasahara and Y. Yamamoto, Angew. Chem., Int. Ed., 2003, 42,
3504; (c) A. V. Bedekar, T. Watanabe, K. Tanaka and K. Fuji,
Tetrahedron: Asymmetry, 2002, 13, 721; (d) S. Brown, S. Clarkson,
R. Grigg and V. Sridharan, Tetrahedron Lett., 1993, 34, 157.
10 (a) T. Hayashi, M. Takahashi, Y. Takaya and M. Ogasawara,
J. Am. Chem. Soc., 2002, 124, 5052; (b) P. Zhao and J. F. Hartwig,
J. Am. Chem. Soc., 2007, 129, 1876.
11 (a) Y. Sato, Y. Oonishi and M. Mori, Organometallics, 2003, 22,
30; (b) K. Aikawa, S. Akutagawa and K. Mikami, J. Am. Chem.
Soc., 2006, 128, 12648.
12 (a) R. T. Yu and T. Rovis, J. Am. Chem. Soc., 2006, 128, 2782;
(b) T. Shibata, H. Kurokawa and K. Kanda, J. Org. Chem., 2007,
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The outcome of eqn (2) is explained by the proposal outlined
in Scheme 3. In the case of path a, the insertion of the olefin in
E-d proceeds stereospecifically via TS-A to generate alkyl-
Rh(I) intermediate F-d, which is oxidized by C–Br to produce
Rh(III)-intermediate H-d. With regard to path b, similar
chemistry also leads to the formation of H-d via TS-B. Finally,
reductive elimination takes place with retention of stereo-
chemistry to yield product (cis)-3a-d. This means that the
information about the Csp2 stereochemistry can be completely
transferred to the corresponding Csp3 center.13 We believe that
this conclusion will be helpful for enantioselective reactions.
This result also provides strong evidence that the formation of
the aryl–Csp3 bond from the aryl-Rh(III)-Csp3 species proceeds
via a direct reductive elimination mechanism.14
13 L. Jiao and Z.-X. Yu, J. Am. Chem. Soc., 2008, 130, 7178.
14 (a) Y. Wang, P. A. Wender and Z.-X. Yu, J. Am. Chem. Soc., 2007,
129, 10060; (b) B. Bennacer, M. Fujiwara and I. Ojima, Org. Lett.,
2004, 6, 3589; (c) B. Bennacer, M. Fujiwara and I. Ojima, J. Am.
Chem. Soc., 2005, 127, 17756.
In summary, we have realized a new rhodium-catalyzed
[2 + 2 + 2] cycloaddition of a 1,6-enyne with 2-bromo-
phenylboronic acid, which was viewed as one two-component
ꢀc
This journal is The Royal Society of Chemistry 2009
Chem. Commun., 2009, 5311–5313 | 5313