7602
S. Nakamura et al. / Tetrahedron Letters 47 (2006) 7599–7602
as a stereocontroller, which shows an excellent enantio-
selectivity through dynamically controlled chirality
on the sulfur atom. A further extension of 2-hetero-
arylsulfonyl groups as a powerful stereocontroller in
combination with chiral ligands is now in progress.
Tetrahedron Lett. 2004, 45, 4213; (c) Watanabe, Y.; Mase,
N.; Furue, R.; Toru, T. Tetrahedron Lett. 2001, 42, 2981.
7
. We also examined the reaction using Bu SnCN and KCN
3
as a cyanation reagent, which gave product 2f in a low
yield.
. Various chiral Lewis acids such as Zn(OTf) -3, Sc(OTf) -
2 3
8
3
, Yb(OTf) -3, Ni(ClO ) Æ6H O-3, FeCl -3, Sn(OTf) -3,
3
4 2
2
3
2
Cu(OTf)
2
-BINAP,
AgOTf-BINAP,
3
Me Al-BINOL,
ZrCl -BINOL, AlCl -PyBOX, and chiral salen-AlCl com-
plexes, afforded product 2f either in low yields or with a
low enantioselectivity.
. Similar aspects for the reversal of stereochemistry have
been reported, see: (a) Sibi, M. P.; Ji, J. J. Org. Chem.
4 3
Acknowledgement
This work was supported by the Daiko Foundation and
Sankyo Award in Synthetic Organic Chemistry, Japan.
9
1
997, 62, 3800; (b) Sibi, M. P.; Matsunaga, H. Tetrahedron
Lett. 2004, 45, 5925.
References and notes
10. The Mg(OTf)2 and DBFOX reaction did not afford
product 2f.
1
2
3
. For reviews, see: (a) Yet, L. Angew. Chem., Int. Ed. 2001,
11. Unfortunately aliphatic 2-pyridylsulfonylimines could not
be obtained from aliphatic aldehydes under various
reaction conditions.
12. We have already reported a similar reaction mechanism in
the alkylation of N-(2-pyridylsulfonyl)imines by the
MOPAC 93/PM3 method, see Ref. 4.
40, 875; (b) Gr o¨ ger, H. Chem. Rev. 2003, 103, 2795; (c)
Vilaivan, T.; Bhanthumnavin, W.; Sritana-Anant, Y.
Curr. Org. Chem. 2005, 9, 1315; For recent report on the
catalytic enantioselective Strecker-type reaction, see:
Blacker, J.; Clutterbuck, L. A.; Crampton, M. R.;
Grosjean, C.; North, M. Tetrahedron: Asymmetry 2006,
13. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G.
E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.,
Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J.
M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.;
Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda,
R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.;
Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.;
Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A.
J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg,
J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.;
Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.;
Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.;
Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.;
Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P.
M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez,
C.; Pople, J. A. Gaussian 03, Revision C.02; Gaussian:
Wallingford, CT, 2004.
14. The origin of the reversed stereochemistry obtained with
bis(oxazoline) 6 is unclear. A possible explanation may be
derived from the fact that the coordinating geometry of
Mg(II) is changed from that with 3; For the tetrahedral
Mg(II) complex, see: (a) Corey, E. J.; Ishihara, K.
Tetrahedron Lett. 1992, 33, 6807; (b) Sibi, M. P.; Sausker,
J. B. J. Am. Chem. Soc. 2002, 124, 984; An octahedral
Mg(II) complex has also been proposed: (c) Sibi, M. P.;
Petrovic, G.; Zimmerman, J. J. Am. Chem. Soc. 2005, 127,
2390; (d) Gothelf, K. V.; Hazell, R. G.; Jørgensen, K. A.
J. Org. Chem. 1998, 63, 5483.
17, 1449.
. Recently, the catalytic enantioselective Strecker-type reac-
tion of N-(trimethylphenylsulfonyl)imines using chiral
quaternary ammonium salts has been reported. The
reaction of N-sulfonylimines derived from aliphatic alde-
hydes affords the products with high ee; however, this
catalytic system cannot be applied to the reaction of
aromatic aldimines, see: Ooi, T.; Uematsu, Y.; Maruoka,
K. J. Am. Chem. Soc. 2006, 128, 2548.
. The achiral Strecker-type reaction to N-tosylimines has
been reported, see: (a) Prasad, B. A. B.; Bisai, A.; Singh,
V. K. Tetrahedron Lett. 2004, 45, 9565; (b) Takahashi, E.;
Fujisawa, H.; Yanai, T.; Mukaiyama, T. Chem. Lett. 2005,
34, 318.
4
. Sugimoto, H.; Nakamura, S.; Hattori, M.; Ozeki, S.;
Shibata, N.; Toru, T. Tetrahedron Lett. 2005, 46, 8941.
. The 2-pyridylsulfonyl group has been used in some
asymmetric inductions, see: (a) Han, H.; Bae, I.; Yoo, E.
J.; Lee, J.; Do, Y.; Chang, S. Org. Lett. 2004, 6, 4109; (b)
Esquivias, J.; Array a´ s, R. G.; Carretero, J. C. J. Org.
Chem. 2005, 70, 7451; (c) Array a´ s, R. G.; Cbrera, S.;
Carretero, J. C. J. Synthesis 2006, 1205; (d) Llamas, T.;
Array a´ s, R. G.; Carretero, J. C. Org. Lett. 2006, 8, 1795;
5
(
4
e) Maule o´ n, P.; Carretero, J. C. Chem. Commun. 2005,
961.
6
. We have reported the highly enantioselective radical
addition to vinylsulfones, in which a chiral Lewis acid
selectively coordinates with one of the enantiotopic
sulfonyl oxygens and nitrogen in the heteroarylsulfonyl
group, see: (a) Sugimoto, H.; Nakamura, S.; Watanabe,
Y.; Toru, T. Tetrahedron: Asymmetry 2003, 14, 3045; (b)
Sugimoto, H.; Kobayashi, K.; Nakamura, S.; Toru, T.