Chiral C
2
-Boron-Bis(oxazolines) in Asymmetric Catalysis
FULL PAPER
ω
scans, crystal-to-detector distance 5.0 cm. The software
S. W. Tregay, J. Am. Chem. Soc. 1999, 121, 686–699; l) D. A.
Evans, K. A. Scheidt, J. N. Johnston, M. C. Willis, J. Am.
Chem. Soc. 2001, 123, 4480–4491; m) D. A. Evans, D. M.
Barnes, J. S. Johnson, T. Lectka, P. von Matt, S. J. Miller, J. A.
Murry, R. D. Norcross, E. A. Shaughnessy, K. R. Campos, J.
Am. Chem. Soc. 1999, 121, 7582–7594; n) D. A. Evans, S. J.
Miller, T. Lectka, P. von Matt, J. Am. Chem. Soc. 1999, 121,
[
30a]
SMART
was used for collecting frames of data, indexing reflec-
tions and determination of lattice parameters. The collected frames
were then processed for integration by software SAINT
[30a]
and an
[
30b]
empirical absorption correction was applied with SADABS.
The structures were solved by direct methods (SIR 97)[
30c]
and sub-
sequent Fourier syntheses and refined by full-matrix least-squares
calculations on F (SHELXTL)
parameters to the non-hydrogen atoms. The aromatic hydrogen
atoms were placed in calculated positions and refined with ideal-
ized geometry [C(sp )–H 0.93 Å] whereas the other H atoms were
located in the Fourier map and refined isotropically. Crystal data
and details of the data collection for 4 and 6 are reported in
Table 1.
7559–7573; o) D. A. Evans, T. Rovis, M. C. Kozlowski, J. S.
2
[31]
attributing anisotropic thermal
Tedrow, J. Am. Chem. Soc. 1999, 121, 1994–1995.
[4] M. I. Burguete, J. M. Fraile, J. I. Garcia, E. Garcia-Verdugo,
C. I. Herrerias, J. Luis, S. V. A. Mayoral, J. Org. Chem. 2001,
66, 8893–8901 and references cited therein.
2
[
5] R. Annunziata, M. Benaglia, M. Cinquini, F. Cozzi, M. Pitillo,
J. Org. Chem. 2001, 66, 3160–3166.
[
6] a) H. W. Görlitzer, M. Spiegler, R. Arwander, J. Chem. Soc.,
Dalton Trans. 1999, 4287; b) R. Schumacher, F. Dammast,
R. H. U. Reißig, Chem. Eur. J. 1997, 3, 614–619; c) J. M.
Brown, P. J. Guiry, D. W. Price, M. B. Hursthouse, K. Karulov,
Tetrahedron: Asymmetry 1994, 5, 561–564; d) D. Müller, G.
Umbricht, B. Weber, A. Pfaltz, Helv. Chim. Acta 1991, 74, 232–
CCDC-163357 and -278924 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
240.
B) Computational Details: All the DFT computations reported here
have been performed with the Gaussian 98[ series of programs
using the non-local hybrid Becke’s three-parameter exchange func-
tional (denoted as B3LYP in the Gaussian formalism) and locally
[7] V. Schultze, R. W. Hoffmann, Chem. Eur. J. 1999, 5, 337–344.
[8] M. Nakamura, A. Hirai, M. Sogi, E. Nakamura, J. Am. Chem.
Soc. 1998, 120, 5846–5847.
[9] R. P. Singh, Bull. Soc. Chim. Fr. 1997, 134, 765–768.
[10] a) M. Bandini, P. G. Cozzi, L. Negro, A. Umani-Ronchi,
Chem. Commun. 1999, 39–40; b) M. Bandini, F. Bernardi, A.
Bottoni, P. G. Cozzi, G. P. Miscione, A. Umani-Ronchi, Eur. J.
Org. Chem. 2003, 2972–2984.
32]
dense basis sets (LDBS).[33] According to the LDBS approach, in
all geometry optimizations the system has been partitioned into
two different regions, which were assigned basis sets of different
accuracy. One region contains the atoms directly involved in the
reaction or in the formation of hydrogen bonds. In this case we
have used the DZVP basis, which is a Local Spin Density (LSD)-
[
[
11] J. E. Parks, R. H. Holm, Inorg. Chem. 1968, 7, 1408–1416.
12] C. E. Radzewich, M. P. Coles, R. F. J. Jordan, J. Am. Chem.
Soc. 1998, 120, 9384–9385.
[34]
optimized basis set of double-zeta quality. This basis, which in-
cludes polarization functions, is suitable to describe weak hydrogen
interactions such as those occurring in the system investigated here.
The other region includes all the remaining atoms. For these atoms,
contained within the contour line in Figure 4, the 3-21G* basis
[
13] B. Qian, S. W. Baek, M. R. Smith III, Polyhedron 1999, 18,
2405–2414.
[14] M. Bandini, P. G. Cozzi, M. Monari, R. Pierciaccante, S. Selva,
A. Umani-Ronchi, Chem. Commun. 2001, 1318–1319.
[15] For enantioselective reduction of ketones with boranes see: a)
J. Xu, T. Wei, Q. Zhang, J. Org. Chem. 2004, 69, 6860–6866;
b) J. Xu, T. Wei, Q. Zhang, J. Org. Chem. 2003, 68, 10146–
[
32]
set has been employed. To obtain more accurate energy values,
single-point calculations have been performed using the DZVP ba-
sis set on all atoms. The geometry of the various critical points on
the reaction surface has been fully optimized with the gradient
method available in Gaussian 98. A computation of the harmonic
vibrational frequencies has been carried out to determine the na-
ture of each critical point and the ZPE correction has been added
to all the energy values.
1
0151; c) N. J. Gilmore, S. Jones, Tetrahedron: Asymmetry
2
003, 14, 2115–2118; d) S. M. Nettles, K. Matos, E. R. Burkh-
ardt, D. R. Rouda, J. A. Corella, J. Org. Chem. 2002, 67, 2970–
2
976; e) H. S. Wilkinson, G. J. Tanoury, S. A. Wald, C. H. Sen-
anayake, Org. Process Res. Dev. 2002, 6, 146–148; f) C.
Puigjaner, A. Vidal-Ferran, A. Moyano, M. A. Pericas, A. Ri-
era, J. Org. Chem. 1999, 64, 7902–7911. For review: see, g) E. J.
Corey, C. J. Helal, Angew. Chem. Int. Ed. 1998, 37, 1986–2012;
h) V. A. Glushkov, A. G. Tolstikov, Russian Chem. Rev. 2004,
Supporting Information (see also the footnote on the first page of
this article): Calculated transition states for TS1(S)Ј and TS1(R)Ј.
73, 581–608; i) M. Wills, J. Hannedouche, Curr. Opin. Drug
Discovery Dev. 2002, 5, 881–891; j) J. M. Brunel, G. Buono,
Top. Curr. Chem. 2002, 220 (New Aspects, in: Phosphorus
Chemistry I), 79–105; k) M. Wills, M. Gamble, M. Palmer, A.
Smith, J. Studley, J. Kenny, J. Mol. Catal. A 1999, 146, 139–
[
[
[
1] T. P. Yoon, E. N. Jacobsen, Science 2003, 299, 1691–1693.
2] A. Pfaltz, Synlett 1999, 835–843.
3] For recent examples of C
as catalysts, see: a) J. S. Johnson, D. A. Evans, Acc. Chem. Res.
000, 33, 325–335; b) N. Gathergood, W. Zhuang, K. A.
2
-bis(oxazoline) Lewis acid complexes
148.
[
16] a) G. Alagona, C. Ghio, M. Persico, S. Tomasi, J. Am. Chem.
Soc. 2003, 125, 10027–10039 and references cited therein; b) W.
Harb, M. F. Ruiz-López, F. Coutrot, C. Grison, P. Coutrot,
J. Am. Chem. Soc. 2003, 126, 6996–7008 and references cited
therein.
17] V. Stepanenko, M. Ortiz-Marciales, W. Correa, M. De Jesùs, S.
Espinosa, L. Ortiz, Tetrahedron: Asymmetry 2006, 17, 112–115.
18] S. Dagorne, S. Bellemin-Laponnaz, R. Welter, Organometallics
2
Jørgensen, J. Am. Chem. Soc. 2000, 122, 12517–12522; c) K. B.
Jensen, J. Thorhauge, R. G. Hazell, K. A. Jørgensen, Angew.
Chem. Int. Ed. 2001, 40, 160–163; d) H. Audrain, K. A.
Jørgensen, J. Am. Chem. Soc. 2000, 122, 11543–11544; e) K.
Juhl, N. Gathergood, K. A. Jørgensen, Angew. Chem. Int. Ed.
[
[
[
2
001, 40, 2995–2997; f) K. R. Knudsen, T. Risgaard, N. Nishi-
waki, K. V. Gothelf, K. A. Jørgensen, J. Am. Chem. Soc. 2001,
23, 5843–5844; g) N. Nishiwaki, K. R. Knudsen, K. V. Go-
2004, 23, 3053–3061.
1
19] S. Hong, S. Tian, M. V. Metz, T. J. Marks, J. Am. Chem. Soc.
2003, 125, 14768–14783.
[20] A. Hashiguchi, K. J. Fujii, K. Haack, T. Matsumura, R. Ika-
riya, R. Noyori, Angew. Chem. Int. Ed. Engl. 1997, 36, 288–
290.
thelf, K. A. Jørgensen, Angew. Chem. Int. Ed. 2001, 40, 2992–
2
995; h) K. Juhl, K. A. Jørgensen, J. Am. Chem. Soc. 2002,
124, 2420–2421; i) J. Thorhauge, M. Roberson, R. G. Hazell,
K. A. Jørgensen, Chem. Eur. J. 2002, 8, 1888–1898; j) D. A.
Evans, M. C. Kozlowski, J. A. Murry, C. S. Burgey, K. R.
Campos, B. T. Connell, R. J. Staples, J. Am. Chem. Soc. 1999,
[21] J. B. Morrison, E. Grandbois, S. I. Howard, J. Org. Chem.
121, 669–685; k) D. A. Evans, C. S. Burgey, M. C. Kozlowski,
1980, 45, 4229–4231.
Eur. J. Org. Chem. 2006, 4596–4608
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4607