2672
T. Arai et al.
LETTER
{N-benzyl[(4S,5S)-4,5-dihydro-4,5-diphenyl-1-tosyl-1H-imida-
zol-2-yl]-N-{[(4S,5S)-4,5-dihydro-4,5-diphenyl-1-tosyl-1H-imi-
dazol-2-yl]methyl}methanamine} (4)
References
(1) (a) Asymmetric Catalysis in Organic Synthesis; Noyori, R.,
Ed.; Wiley: New York, 1994. (b) Comprehensive
Asymmetric Catalysis; Jacobsen, E. N.; Pfaltz, A.;
Yamamoto, H., Eds.; Springer: Berlin, 1999. (c) Transition
Metals for Organic Synthesis, 2nd ed.; Beller, M.; Bolm, C.,
Eds.; Wiley-VCH: Weinheim, 2004.
(2) (a) Ghosh, A. K.; Mathivanan, P.; Cappiello, J. Tetrahedron:
Asymmetry 1998, 9, 1. (b) Jørgensen, K. A.; Johannsen, M.;
Yao, S.; Audrain, H.; Thorhauge, J. Acc. Chem. Res. 1999,
32, 605.
(3) Recent progress on chiral ligands containing imidazoline
motif: (a) Morimoto, T.; Tachibana, K.; Achiwa, K. Synlett
1997, 783. (b) Davenport, A. J.; Davies, D. L.; Fawcett, J.;
Russell, D. R. J. Chem. Soc., Perkin Trans. 1 2001, 1500.
(c) Menges, F.; Neuburger, M.; Pfaltz, A. Org. Lett. 2002, 4,
4713. (d) Busacca, C. A.; Grossbach, D.; So, R. C.; O’Brien,
E. M.; Spinelli, E. M. Org. Lett. 2003, 5, 595. (e) Casey,
M.; Smyth, M. P. Synlett 2003, 102. (f) Guiu, E.; Claver, C.;
Benet-Buchholz, J.; Castillón, S. Tetrahedron: Asymmetry
2004, 15, 3365. (g) Bastero, A.; Claver, C.; Ruiz, A.;
Castillón, S.; Daura, E.; Bo, C.; Zangrando, E. Chem. Eur. J.
2004, 10, 3747.
To the solution of 3 (353 mg, 0.83 mmol) in DMF was added Et3N
(171 mL, 1.22 mmol ), NaI (184 mg, 1.23 mmol), and benzyl amine
(48 mL, 0.41 mmol), and the mixture was stirred for 8 h at r.t. The
reaction was quenched by sat. NaHCO3, and the aqueous layer was
extracted by Et2O. After washing the combined organic extracts
with H2O three times, the organic layer was dried over anhyd
Na2SO4, and concentrated in vacuo after filtration. The residual
crude product was purified by silica gel column chromatography to
give the N-tethered bis(imidazoline) 4 (178 mg, 49% yield) as a pale
yellow amorphous solid.
Spectral data of 4: 1H NMR (400 MHz, CDCl3): d = 2.32 (s, 6 H),
4.29 (s, 2 H), 4.31–4.36 (dd, J = 1.7, 17.1 Hz, 2 H, CH2), 4.39–4.43
(d, J = 17.1 Hz, 2 H, CH2), 4.83 (d, J = 5.1 Hz, 2 H, CH), 4.98 (d,
J = 5.1 Hz, 2 H, CH), 6.90 (dd, J = 1.7, 8.0 Hz, 4 H, aromatic), 6.98
(d, J = 8.0 Hz, 4 H, aromatic), 7.18–7.40 (m, 25 H, aromatic). 13
C
NMR (100 MHz, CDCl3): d = 21.5, 51.2, 57.0, 71.5, 78.0, 126.2,
126.5, 127.2, 127.4, 127.5, 128.0, 128.3, 128.6, 128.9, 129.4, 129.6,
135.6, 138.7, 141.5, 141.6, 144.1, 157.0. HRMS (FAB+): m/z calcd
for C53H50N5O4S2 [M+ + H]: 884.3304; found: 884.3252.
Catalytic Asymmetric Cyclopropanation (Table 1, Entry 2)
Nb-imidazoline (4, 23.0 mg, 0.026 mmol) and Cu(OTf)2 (7.2 mg,
0.02 mmol) were dissolved in dry CH2Cl2 under Ar atmosphere, and
the resulting blue color solution was stirred for 12 h. To the solution
was added styrene (230 mL, 2 mmol), and 0.4 M solution of ethyl
diazoacetate in CH2Cl2 (1.0 mL) was slowly added over 4 h at r.t.
After being stirred for further 3 h at the same temperature, the reac-
tion was quenched by H2O, and the aqueous layer was extracted by
CHCl3. The combined organic extracts were dried over anhyd
Na2SO4, and concentrated in vacuo after filtration. The residual
crude product was purified by silica gel column chromatography to
give the trans-adduct (62 mg 81% yield) and cis-adduct (11 mg
15% yield). The ee of the adducts were determined by chiral station-
ary phase HPLC analysis (DAICEL CHIRALCEL OJ-H, flow
rate = 0.5 mL/min, hexane–2-PrOH = 9:1).
(4) Zhang et al. reported the N-tethered bis(oxazoline) as
ambox: Jiang, Y.; Jiang, Q.; Zhang, X. J. Am. Chem. Soc.
1998, 120, 3817.
(5) Mylari, B. L.; Scott, P. J.; Zembrowski, W. J. Synth.
Commun. 1989, 19, 2921.
(6) Nb-imidazoline is an abbreviation of N-tethered
bis(imidazoline).
(7) Recent progress in Cu-bis(oxazoline)-catalyzed asymmetric
benzoylation of 1,2-diol: (a) Matsumura, Y.; Maki, T.;
Murakami, S.; Onomura, O. J. Am. Chem. Soc. 2003, 125,
2052. (b) Matsumura, Y.; Maki, T.; Tsurumaki, K.;
Onomura, O. Tetrahedron Lett. 2004, 45, 9131. (c) Gissibl,
A.; Finn, M. G.; Reiser, O. Org. Lett. 2005, 7, 2325.
(8) During the preparation of this manuscript, Beller et al.
reported a similar type of pyridinebisimidazoline ligand for
a Ru-catalyzed asymmetric epoxidation: Bhor, S.;
Anilkumar, G.; Tse, M. K.; Klawonn, M.; Döbler, C.;
Bitterlich, B.; Grotevendt, A.; Beller, M. Org. Lett. 2005, 7,
3393.
Acknowledgment
This work was supported by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Science, Sports, Culture and
Technology of Japanese Government. We thank Mr. Masahiko
Watanabe and Mr. Akitsugu Fujiwara for their kind technical
support and helpful discussion.
Synlett 2005, No. 17, 2670–2672 © Thieme Stuttgart · New York