378
D. Xiong et al. / Tetrahedron: Asymmetry 21 (2010) 374–378
116.64, 114.18, 60.40, 56.82, 50.14, 30.60, 24.31; ½a D20
ꢁ
¼ þ36:75 (c
romethane (0.5 mL) at room temperature. After the mixture had
been stirred for 30 min, a drop of water was added and the resul-
tant mixture was stirred for 30 min. Then the reaction mixture was
stirred at room temperature for 9 h after styrene (0.1 mmol), n-
nonane (as an internal standard) and 50% aqueous hydrogen per-
oxide (0.3 mmol) were added. After the epoxidation reaction,
anhydrous Na2SO4 was added. The yield and the ee were deter-
mined by GC analysis without further manipulations.
0.0090, CH2Cl2). HRMS(ESI-MS): m/z: calcd for C50H46N2O4:
738.3530, found: 739.3536 [M+H]+.Ligand 9: mp 141–144 °C; 1H
NMR (CDCl3):d 7.98–7.65 (m, 6H), 7.52–7.00 (m, 16H), 4.20–4.05
(m, 4H), 3.72–3.65 (m, 6H), 2.48–2.40 (m, 2H), 2.17–2.00 (m, 2H),
1.65–1.58 (m, 2H), 1.20–1.00 (m, 4H); 13C NMR (CDCl3): d 155.07,
153.22, 133.92, 133.80, 129.58, 129.40, 128.38, 128.12, 127.96,
127.40, 126.52, 125.88, 125.71, 125.12, 124.68, 123.56, 122.93,
119.01, 116.66, 114.19, 60.09, 56.82, 50.16, 30.60, 24.31;
½
a 2D0
ꢁ
¼ ꢀ31:3 (c 0.0073, CH2Cl2). HRMS(ESI-MS): m/z: calcd for
Acknowledgment
C50H46N2O4: 738.3530, found: 739.3540 [M+H]+.
We are grateful for the financial support from the Chinese Acad-
emy of Sciences and National Natural Science Foundation of China
(20873166, 20625308).
4.3. Preparation of salalen ligands 10 and 11
The synthesis of salalen ligands 10 and 11 was according to the
modular procedure for salalen ligands from (R)- or (S)-4.3a,11Ligand
10: mp 176–180 °C; 1H NMR (CDCl3): d 12.99 (s, 1H), 8.61 (s, 1H),
8.02–7.62 (m, 8H), 7.40–6.94 (m, 14H), 4.30–4.20 (m, 2H), 3.70 (s,
6H), 3.22–3.02 (m, 1H), 2.85–2.75 (m, 1H), 2.11–2.08 (m, 1H),
1.80–1.50 (m, 4H), 1.45–1.15 (m, 3H); 13C NMR (CDCl3): d 166.07,
155.02, 154.25, 135.51, 133.92, 133.76, 133.70, 133.42, 129.70,
129.47, 129.33, 128.79, 128.24, 128.07, 127.53, 127.34, 126.90,
126.50, 126.22, 125.80, 125.32, 125.07, 124.86, 124.60, 123.58,
123.44, 123.27, 122.79, 120.56, 118.60, 117.40, 116.74, 114.25,
114.12, 67.97, 61.62, 56.82, 56.79, 51.10, 33.80, 30.08, 25.61,
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24.35, 24.20; ½a D20
¼ ꢀ71:8 (c 0.0442, CH2Cl2); HRMS(ESI-MS): m/z:
ꢁ
calcd for C50H46N2O4: 736.3374, found: 737.3379 [M+H]+.Ligand
11: mp 164–168 °C; 1H NMR (CDCl3):d 13.03 (s, 1H), 8.49 (s, 1H),
8.02–7.65 (m, 8H), 7.45–7.00 (m, 14H), 4.30–4.17 (m, 2H),3.70–
3.65 (m, 6H), 3.20–3.08 (m, 1H), 2.78–2.76 (m, 1H), 2.11–1.80 (m,
4H), 1.75–1.17 (m, 4H); 13C NMR (CDCl3): d 166.01, 155.06, 155.03,
154.20, 135.51, 133.90, 133.74, 133.69, 133.42, 129.71, 129.47,
129.32, 128.77, 128.24, 128.07, 127.53, 127.39, 126.90, 126.49,
126.24, 125.79, 125.32, 125.05, 124.83, 124.60, 123.58, 123.48,
123.28, 122.79, 120.56, 118.61, 117.38, 116.74, 114.25, 114.14,
67.97, 61.64, 56.80, 56.76, 51.10, 33.80, 30.08, 25.60, 24.35, 24.20;
9. (a) Sun, W.; Wang, H. W.; Xia, C. G.; Li, J. W.; Zhao, P. Q. Angew. Chem., Int. Ed.
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90, 623.
½
a 2D0
ꢁ
¼ ꢀ294:5 (c 0.0047, CH2Cl2); HRMS(ESI-MS): m/z: calcd for
C50H44N2O4: 736.3374, found: 737.3372 [M+H]+.
10. Jin, L. L.; Huang, Y. Z.; Jing, H. W.; Chang, T.; Yan, P. Tetrahedron: Asymmetry
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Schäfer, M. Adv. Synth. Catal. 2007, 349, 2385.
12. CCDC 740842 (salan ligand 7) and CCDC 754008 (Ti complex of salan ligand 7)
contain the supplementary crystallographic data for this Letter. These data can
be obtained free of charge from The Cambridge Crystallographic Data Centre
4.4. Typical procedure for the asymmetric epoxidation of
olefins
To a stirred solution of ligand 6 (10
lmol) in dichloromethane
was added dropwise a solution of Ti (O-i-Pr)4 (10
lmol) in dichlo-