1-ene-, 1-yne- and 1-allene-VCP substrates. The experimental
findings represent the second example where VCP serves as a
three-carbon component in Rh(I)-catalyzed cycloadditions.
The present methodology provides an efficient, versatile and
diastereoselective approach to carbo- and hetero-bicyclic
compounds. The formation of a vinyl substituted quaternary
stereocenter in this process enables further access to functionalized
quaternary-stereocenter-containing cycloadducts. Further
studies on the reaction mechanism, origins of the stereoinduction
and the application of these cycloaddition reactions are
ongoing.
Scheme 2 Further exploration of the substrate scope.
We thank Peking University, the Natural Science Foundation
of China (20825205-National Science Fund for Distinguished
Young Scholars and 20672005) and the Ministry of Education
of China (108001) for financial support.
Notes and references
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Scheme 3 Control experiments.
2 J. Blanco-Urgoiti, L. Anorbe, L. Perez-Serrano, G. Dominguez and
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3 (a) C. Santelli-Rouvier and M. Santelli, Synthesis, 1983, 429;
(b) H. Pellissier, Tetrahedron, 2005, 61, 6479.
4 Selected recent reports on [3 + 2] cycloadditions: (a) J. E. Wilson
´
and G. C. Fu, Angew. Chem., Int. Ed., 2006, 45, 1426; (b) M. Gulıas,
R. Garcıa, A. Delgado, L. Castedo and J. L. Mascarenas, J. Am.
´
Chem. Soc., 2006, 128, 384; (c) L. Liu and J. Montgomery, J. Am.
Chem. Soc., 2006, 128, 5348; (d) S. Ogoshi, M. Nagata and
H. Kurosawa, J. Am. Chem. Soc., 2006, 128, 5350;
(e) B. M. Trost, J. P. Stambuli, S. M. Silverman and U. Schworer,
¨
J. Am. Chem. Soc., 2006, 128, 13328; (f) P. A. Wender, T. J. Paxton
and T. J. Williams, J. Am. Chem. Soc., 2006, 128, 14814;
(g) H.-T. Chang, T. T. Jayanth and C.-H. Cheng, J. Am. Chem.
Soc., 2007, 129, 4166; (h) X. Huang and L. Zhang, J. Am. Chem.
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(k) S. S. Yudha, Y. Kuninobu and K. Takai, Angew. Chem., Int.
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Fig. 1 Plausible catalytic cycle of the [3 + 2] reaction.
5 For representative [5 + x] cycloadditions employing VCP as five-
carbon unit, see: (a) P. A. Wender, H. Takahashi and B. Witulski,
J. Am. Chem. Soc., 1995, 117, 4720; (b) P. A. Wender and
D. Sperandio, J. Org. Chem., 1998, 63, 4164; (c) B. M. Trost,
F. D. Toste and H. Shen, J. Am. Chem. Soc., 2000, 122, 2379;
(d) P. A. Wender, G. G. Gamber, R. D. Hubbard and L. Zhang,
J. Am. Chem. Soc., 2002, 124, 2876; (e) P. A. Wender,
G. G. Gamber, R. D. Hubbard, S. M. Pham and L. Zhang,
J. Am. Chem. Soc., 2005, 127, 2836; (f) Y. Wang, J. Wang, J. Su,
F. Huang, L. Jiao, Y. Liang, D. Yang, S. Zhang, P. A. Wender and
Z.-X. Yu, J. Am. Chem. Soc., 2007, 129, 10060.
6 L. Jiao, S. Ye and Z.-X. Yu, J. Am. Chem. Soc., 2008, 130,
7178.
7 Z.-X. Yu, P. A. Wender and K. N. Houk, J. Am. Chem. Soc., 2004,
126, 9154.
8 Cationic Rh(I)-phosphine complexes were employed as efficient
catalysts in intramolecular cycloaddition reactions, see: B. Wang,
P. Cao and X. Zhang, Tetrahedron Lett., 2000, 41, 8041.
cleavage to generate the key p-allyl rhodacyclo-hexene
intermediate B.7 Then insertion of a CQC or CRC bond
to the C(1)–Rh bond occurs to form the intermediate C, which
undergoes reductive elimination to furnish the bicyclic [3 + 2]
cycloadduct, with the concomitant generation of the catalytic
species for the next catalytic cycle. A minor amount of
the observed byproduct 3 is probably generated through
b-hydride elimination of intermediate C. In the reaction
process, the vinyl group plays an important role as a
‘‘spectator’’ binding group to facilitate the ring-opening of a
cyclopropane ring, well explaining the lack of activity for
ene/yne-cyclopropanes.
In conclusion, we have developed a new type of
Rh(I)-catalyzed intramolecular [3 + 2] cycloaddition of
ꢀc
This journal is The Royal Society of Chemistry 2010
Chem. Commun., 2010, 46, 1059–1061 | 1061