Journal of the American Chemical Society
COMMUNICATION
Angew. Chem., Int. Ed. 2006, 45, 6422. (c) Godula, K.; Sames, D. Science
2006, 312, 67. (d) Bergman, R. G. Nature 2007, 446, 391. (e) Alberico,
D.; Scott, M. E.; Lautens, M. Chem. Rev. 2007, 107, 174. (f) Davies,
H. M. L.; Manning, J. R. Nature 2008, 451, 417. (g) Chen, X.; Engle,
K. M.; Wang, D.-H.; Yu, J.-Q. Angew. Chem., Int. Ed. 2009, 48, 5094. (h)
Jazzar, R.; Hitce, J.; Renaudat, A.; Sofack-Kreutzer, J.; Baudoin, O. Chem.
—Eur. J. 2010, 16, 2654.
(2) For selected recent references, see: (a) Pastine, S. J.; McQuaid,
K. M.; Sames, D. J. Am. Chem. Soc. 2005, 127, 12180. (b) Pastine, S. J.;
Sames, D. Org. Lett. 2005, 7, 5429. (c) Tobisu, M.; Chatani, N. Angew.
Chem., Int. Ed. 2006, 45, 1683. (d) Bajracharya, G. B.; Pahadi, N. K.;
Gridnev, I. D.; Yamamoto, Y. J. Org. Chem. 2006, 71, 6204. (e)
Barluenga, J.; Fananꢀas-Mastral, M.; Aznar, F.; Valdꢀes, C. Angew. Chem.,
Int. Ed. 2008, 47, 6594. (f) McQuaid, K. M.; Sames, D. J. Am. Chem. Soc.
2009, 131, 402. (g) Shikanai, D.; Murase, H.; Hata, T.; Urabe, H. J. Am.
Chem. Soc. 2009, 131, 3166. (h) Tobisu, M.; Nakai, H.; Chatani, N.
J. Org. Chem. 2009, 74, 5471. (i) Yang, S.; Li, Z.; Jian, X.; He, C. Angew.
Chem., Int. Ed. 2009, 48, 3999. (j) Mahoney, S. J.; Moon, D. T.;
Hollinger, J.; Fillion, E. Tetrahedron Lett. 2009, 50, 4706. (k) Vadola,
P. A.; Sames, D. J. Am. Chem. Soc. 2009, 131, 16525. (l) Mori, K.;
Kawasaki, T.; Sueoka, S.; Akiyama, T. Org. Lett. 2010, 12, 1732. (m)
Jurberg, I. D.; Odabachian, Y.; Gagosz, F. J. Am. Chem. Soc. 2010,
132, 3543. (n) Zhou, G.; Zhang, J. Chem. Commun. 2010, 46, 6593. (o)
Mori, K.; Sueoka, S.; Akiyama, T. J. Am. Chem. Soc. 2011, 133, 2424.
(3) These types of reactions have been classified under the term “tert-
amino effect”. For reviews, see: (a) Meth-Cohn, O.; Suschitzky, H. Adv.
Heterocycl. Chem. 1972, 14, 211. (b) Verboom, W.; Reinhoudt, D. N. Recl.
Trav. Chim. Pays-Bas 1990, 109, 311. (c) Meth-Cohn, O. Adv. Heterocycl.
Chem. 1996, 65, 1. (d) Quintela, J. M. Recent Res. Dev. Org. Chem. 2003,
7, 259. (e) Matyus, P.; Elias, O.; Tapolcsanyi, P.; Polonka-Balint, A.;
Halasz-Dajka, B. Synthesis 2006, 2625.
(4) (a) Reinhoudt, D. N.; Visser, G. W.; Verboom, W.; Benders,
P. H.; Pennings, M. L. M. J. Am. Chem. Soc. 1983, 105, 4775–4781.
(b) Verboom, W.; Reinhoudt, D. N.; Visser, R.; Harkema, S. J. Org.
Chem. 1984, 49, 269. (c) Nijhuis, W. H. N.; Verboom, W.; Reinhoudt,
D. N.; Harkema, S. J. Am. Chem. Soc. 1987, 109, 3136. (d) Nijhuis,
W. H. N.; Verboom, W.; Reinhoudt, D. N. Synthesis 1987, 641. (e)
Groenen, L. C.; Verboom, W.; Nijhuis, W. H. N.; Reinhoudt, D. N.; Van
Hummel, G. J.; Feil, D. Tetrahedron 1988, 44, 4637. (f) Nijhuis,
W. H. N.; Verboom, W.; Abu El-Fadl, A.; Harkema, S.; Reinhoudt,
D. N. J. Org. Chem. 1989, 54, 199. (g) Nijhuis, W. H. N.; Verboom, W.;
Abu El-Fadl, A.; Van Hummel, G. J.; Reinhoudt, D. N. J. Org. Chem.
1989, 54, 209. (h) De Boeck, B.; Jiang, S.; Janousek, Z.; Viehe, H. G.
Tetrahedron 1994, 50, 7075. (i) De Boeck, B.; Janousek, Z.; Viehe, H. G.
Tetrahedron 1995, 51, 13239. (j) Ojea, V.; Muinelo, I.; Quintela, J. M.
Tetrahedron 1998, 54, 927. (k) Kaval, N.; Halasz-Dajka, B.; Vo-Thanh,
G.; Dehaen, W.; Van der Eycken, J.; Matyus, P.; Loupy, A.; Van der
Eycken, E. Tetrahedron 2005, 61, 9052. (l) Zhang, C.; Kanta De, C.; Mal,
R.; Seidel, D. J. Am. Chem. Soc. 2008, 130, 416. (m) Polonka-Bꢀalint, A.;
Saraceno, C.; Ludꢀanyi, K.; Bꢀenyei, A.; Mꢀatyus, P. Synlett 2008, 2846. (n)
Murarka, S.; Zhang, C.; Konieczynska, M. D.; Seidel, D. Org. Lett. 2009,
11, 129. (o) Ruble, J. C.; Hurd, A. R.; Johnson, T. A.; Sherry, D. A.;
Barbachyn, M. R.; Toogood, P. L.; Bundy, G. L.; Graber, D. R.; Kamilar,
G. M. J. Am. Chem. Soc. 2009, 131, 3991. (p) McQuaid, K. M.; Long,
J. Z.; Sames, D. Org. Lett. 2009, 11, 2972. (q) F€oldi, A. A.; Ludꢀanyi, K.;
Bꢀenyei, A. C.; Mꢀatyus, P. Synlett 2010, 2109. (r) Dunkel, P.; Tꢀurꢀos, D.;
Bꢀenyei, A.; Ludꢀanyi, K.; Mꢀatyus, P. Tetrahedron 2010, 66, 2331. (s)
Alajarin, M.; Bonillo, B.; Ortin, M.-M.; Sanchez-Andrada, P.; Vidal, A.;
Orenes, R.-A. Org. Biomol. Chem. 2010, 8, 4690.
Figure 2. Plausible transition state.
enantiotopic hydrogen by a chiral phosphoric acid did occur in
our system.20,21
We propose for this asymmetric reaction the transition state
shown in Figure 2. Because of the steric repulsion between the
aromatic ring of the N-benzyl group and the aromatic group at
the 3 or 30 position of the catalyst, the benzyl group is located on
the opposite side (β-side) relative to the aromatic ring at the 3 or
30 position.21 In this case, Hβ is too far away to be transferred to
the olefinic carbon, and as a result, HR migrates preferentially.
Subsequent highly stereoselective cyclization affords (S)-4 as the
major enantiomer.
In summary, we have developed a chiral phosphoric acid-
catalyzed asymmetric C(sp3)ꢀH functionalization. A range of
substrates are viable in our reaction: various N,N-dibenzyl sub-
strates and some N-alkyl substrates afforded tetrahydroquinoline
derivatives with good to excellent enantioselectivities. It is worth
noting that this process involves the selective activation of enantio-
topic hydrogen by means of a chiral phosphoric acid. Further
investigations into the development of another chiral transfor-
mation by exploiting this type of reaction are underway in our
laboratory.
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental procedures, ana-
b
lytical and spectroscopic data for new compounds, copies of NMR
and HPLC spectra, and crystallographic data for 4d and s30
(CIF). This material is available free of charge via the Internet at
’ AUTHOR INFORMATION
Corresponding Author
(5) For other types of internal redox reactions, see: (a) Pahadi, N. K.;
Paley, M.; Jana, R.; Waetzig, S. R.; Tunge, J. A. J. Am. Chem. Soc. 2009,
131, 16626. (b) Zhang, C.; Seidel, D. J. Am. Chem. Soc. 2010, 132, 1798.
(c) Deb, I.; Seidel, D. Tetrahedron Lett. 2010, 51, 2945. (d) Zhang, C.;
Das, D.; Seidel, D. Chem. Sci. 2011, 2, 233.
’ ACKNOWLEDGMENT
This work was partially supported by a Grant-in-Aid for Scientific
Research from the Japan Society for the Promotion of Science.
(6) Mori, K.; Ohshima, Y.; Ehara, K.; Akiyama, T. Chem. Lett. 2009,
38, 524.
(7) For Brønsted acid-catalyzed internal redox reactions, see: (a)
Che, X.; Sheng, L.; Dang, Q.; Bai, X. Synlett 2008, 2373. (b) Zhang, C.;
’ REFERENCES
(1) For recent reviews of CꢀH activation, see: (a) Kakiuchi, F.;
Chatani, N. Adv. Synth. Catal. 2003, 345, 1077. (b) Davies, H. M. L.
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dx.doi.org/10.1021/ja2014955 |J. Am. Chem. Soc. 2011, 133, 6166–6169