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D. R. Owen, S. C. Smith and M. J. Gaunt, Angew. Chem., Int. Ed.,
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and M. J. Gaunt, Angew. Chem., Int. Ed., 2004, 43, 4641; (c)
X.-M. Deng, P. Cai, S. Ye, X.-L. Sun, W.-W. Liao, K. Li, Y. Tang,
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W.-W. Liao, K. Li and Y. Tang, J. Am. Chem. Soc., 2003, 125, 13030;
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M. Porcelloni, Angew. Chem., Int. Ed., 2001, 40, 1433.
Fig. 1 ORTEP representation of 4 with ellipsoids shown at 50%
probability level. Hydrogen atoms are omitted for clarity.
6 For some exceptions, see: (a) H. Kakei, T. Sone, Y. Sohtome,
S. Matsunaga and M. Shibasaki, J. Am. Chem. Soc., 2007, 129, 13410;
(b) A. R. Lippert, J. Kaeobamrung and J. W. Bode, J. Am. Chem. Soc.,
2006, 128, 14738; (c) R. K. Kunz and D. W. C. Macmillan, J. Am.
Chem. Soc., 2005, 127, 3240; (d) A. Mamai and J. S. Madalengoitia,
Tetrahedron Lett., 2000, 41, 9009; (e) S. Yamazaki, M. Tanaka and
S. Yamabe, J. Org. Chem., 1996, 61, 4046.
7 T. Kano, T. Hashimoto and K. Maruoka, J. Am. Chem. Soc., 2006,
128, 2174.
Scheme 2 Titanium-BINOLate catalyzed asymmetric cyclopropanation
8 L. Casarrubios, J. A. Pe´rez, M. Brookhart and J. L. Templeton, J. Org.
Chem., 1996, 61, 8358.
reaction.
9 For the denitrogenative cyclopropanation of isolated 1-pyrazolines, see:
(a) J. L. Garc´ıa Ruano, M. T. Peromingo, M. R. Mart´ın and A. Tito,
Org. Lett., 2006, 8, 3295; (b) J. L. Garc´ıa Ruano, S. A. Alonso de Diego,
M. R. Mart´ın, E. Torrente and A. M. Mart´ın Castro, Org. Lett., 2004,
6, 4945; (c) L. A. Adams, V. K. Aggarwal, R. V. Bonnert, B. Bressel,
R. J. Cox, J. Shepherd, J. de Vicente, M. Walter, W. G. Whittingham
and C. L. Winn, J. Org. Chem., 2003, 68, 9433; (d) E. Muray,
A. Alvarez-Larena, J. F. Piniella, V. Branchadell and R. M. Ortun˜o,
J. Org. Chem., 2000, 65, 388 and references therein.
To test the viability of the asymmetric variant, (S)-BINOL–
Ti(Oi-Pr)4 (2
: 1 molar ratio) catalyzed cyclopropanation
reaction of tert-butyl phenyldiazoacetate and a-benzoyloxyacrolein
was examined (Scheme 2). Although the reaction was sluggish
even at 0 uC, providing the cyclopropane in only moderate
enantioselectivity, our preliminary study clearly indicated the
possibility of further refining the Lewis acid catalyzed asymmetric
cyclopropanation.
10 For the mechanistic study of the cyclopropanation reported herein,
see: ESI.
In summary, we demonstrated the effectiveness of acid catalyzed
Michael-initiated cyclopropanation reactions for the preparation
of sterically congested cyclopropanes in a highly diastereoselective
manner. Our research also shed light on the use of aryldiazoace-
tates in acid catalysis, which is a truly unexplored area in organic
synthesis. Research is currently underway to develop catalytic
asymmetric methods and chiral auxiliary based approaches.
This work was partially supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
11 (a) M. P. Doyle, W. E. Buhro and J. F. Dellaria, Jr., Tetrahedron Lett.,
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14 The trans isomer refers to the geometry of the cyclopropane in which the
carboxylate group and the aldehyde are directed trans to each other.
15 For representative examples of Brønsted acid catalyzed activation of
a,b-unsaturated carbonyl compounds, see: (a) D. Nakashima and
H. Yamamoto, J. Am. Chem. Soc., 2006, 128, 9626; (b) J. M. Mahoney,
C. R. Smith and J. N. Johnston, J. Am. Chem. Soc., 2005, 127, 1354.
16 Isolated as a mixture of rotamers (1 : 0.36), which might be derived from
the aryl–cyclopropyl bond axis.
Notes and references
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(b) C. R. Holmquist and E. J. Roskamp, Tetrahedron Lett., 1992, 33,
1131.
18 K. Ishihara and K. Nakano, J. Am. Chem. Soc., 2005, 127, 10504.
19 Crystal data for 4: Mr = 439.51, monoclinic, space group P21/n,
a = 11.040(3), b = 7.235(2), c = 28.628(7) s, b = 91.016(12)u, V =
2286.3(11) s3, Z = 4, Dcalc = 1.277 g cm23, T = 25 uC, m(MoKa) =
0.909 cm21. 21055 reflections were measured, R(all data) = 0.0701,
Rw(all data) = 0.1576. CCDC 652122. For crystallographic data in CIF
or other electronic format see DOI: 10.1039/b715803c.
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4 For recent examples of cyclopropanations based on the metal catalyzed
decomposition of aryldiazoacetates, see: (a) J. L. Thompson and
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