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temperature was then raised to room temperature over a
period of 2 h. After stirred for overnight, the reaction
was quenched with water (20 mL) and extracted CH2Cl2
(three times). The combined organic layer was dried with
Na2SO4. After removal of solvent under reduced pressure
and purification by repeated flash column chromatography
with petroleum-ether:EtOAc (20:1), 13 mg (7% yields) of 1b
and 7 mg (4% yields) of 2b were obtained. Ligand 1b:1H
NMR (300 MHz, CDCl3): d 0.68 (s, 3H), 1.31 (d,
J = 9.9 Hz, 1H), 1.43 (s, 3H), 1.44 (d, J = 6.9 Hz, 3H),
2.15–2.20 (m, 1H), 2.55–2.62 (m, 1H), 2.81 (t, J = 5.7 Hz,
1H), 3.22–3.26 (m, 1H), 7.29 (d, J = 7.8 Hz, 1H), 7.37 (d,
J = 3.3, 1H), 7.86 (d, J = 7.8 Hz, 1H), 7.87 (d,
J = 3.3 Hz, 1H); 13C NMR (CDCl3): d 18.16, 20.97,
26.31, 28.53, 38.71, 41.49, 46.64, 47.326, 116.58, 120.44,
133.54, 143.28, 148.39, 152.21, 161.00, 170.64; ESI-MS
m/z: 271 (M+ + H). Ligand 2b: 1H NMR (300 MHz,
CDCl3): d 0.67 (s, 3H), 1.31 (d, J = 9.9 Hz, 1H), 1.43 (s,
3H), 1.44 (s, 3H), 2.14–2.21 (m, 1H), 2.54 (s, 3H), 2.56–
2.61 (m, 1H), 2.80 (t, J = 5.4 Hz, 1H), 3.21–3.25 (m, 1H),
6.95 (d, J = 0.9 Hz, 1H), 7.27 (s, 1H), 7.95 (d, J = 7.5 Hz,
1H); 13C NMR (CDCl3): d 17.30, 18.11, 20.91, 26.28,
28.50, 38.66, 41.42, 46.61, 47.24, 115.12, 116.26, 133.33,
143.08, 148.60, 153.62, 160.80, 169.64; mass spectrum
m/z: 284 (M+ + H).
21.04, 22.27, 26.36, 29.16, 30.48, 41.71, 41.88, 46.92,
48.96, 115.09, 115.51, 116.02, 133.34, 143.45, 148.43,
153.75, 159.55; ESI-MS m/z: 313 (M+ + H).
3.9. Ligand 2d
1-Iodopropane and 2a were used: 0.11 g (43% yields); 1H
NMR (300 MHz, CDCl3): d 0.64 (s, 3H), 1.00 (q,
J = 6.9 Hz, 6H), 1.29 (d, J = 9.9 Hz, 1H), 1.42 (s, 3H),
1.48–1.57 (m, 3H), 1.64–1.73 (m, 2H), 2.20–2.32 (m, 2H),
2.39 (s, 3H), 2.50–2.55 (m, 2H), 2.71–2.79 (m, 2H), 3.00–
3.04 (m, 1H), 7.23 (d, J = 7.8 Hz, 1H), 7.75 (d,
J = 7.8 Hz, 1H); 13C NMR (CDCl3): d 13.65, 14.37,
15.10, 20.89, 24.92, 26.40, 28.37, 28.64, 34.70, 34.77,
43.49, 43.56, 43.70, 46.99, 114.92, 115.38, 115.89, 133.01,
142.19, 148.76, 160.09, 165.31; ESI-MS m/z: 355
(M+ + H).
3.10. Ligand 2e
1
1-Iodobutane and 2a were used: 0.12 g (45% yields); H
NMR (300 MHz, CDCl3): d 0.6–1.78 (19H), 0.64 (s, 3H),
1.42 (s, 3H), 2.29–2.32 (m, 1H), 2.39 (s, 3H), 2.50–2.59
(m, 1H), 2.76 (t, J = 6.9 Hz, 1H), 2.94–3.02 (m, 1H), 7.22
(d, J = 7.8 Hz, 1H), 7.78 (d, J = 7.5 Hz, 1H); 13C NMR
(CDCl3): d 13.74, 14.11, 15.00, 20.89, 22.13, 22.92, 26.32,
26.38, 28.36, 30.04, 32.19, 33.75, 41.08, 43.56, 43.89,
47.03, 115.57, 119.49, 133.18, 133.50, 134.35, 142.38,
148.92, 160.32; ESI-MS m/z: 383 (M+ + H).
3.7. General procedure for preparation of ligands 2c–2g and
3b–3d
A 100 mL flask was filled with dry THF (5 mL) and
cooled to ꢀ40 ꢁC. Diisopropylamine (3.15 mmol,
0.45 mL) and n-butyllithium (1.6 M solution in hexane,
3.15 mmol, 1.97 mL) were added slowly with stirring. The
temperature was then raised to 0 ꢁC and stirred for
30 min. The mixture was cooled to ꢀ40 ꢁC again and 2a
or 3a (0.7 mmol, 0.19 g) in dry THF (5 mL) was added
slowly. A deep blue solution for 2a or red-brown solution
for 3a was obtained and the resulting mixture was kept
at ꢀ40 ꢁC for 2 h. The appropriate iodoalkane (3–6 mmol)
was added slowly to the mixture. The temperature was
raised to room temperature over a period of 2 h and the
solution was kept stirred overnight. The reaction was
quenched with water (20 mL) and extracted with CH2Cl2
(three times). The combined organic layer was dried with
Na2SO4. After removal of solvent under reduced pressure,
the crude product was purified by flash column
chromatography.
3.11. Ligand 2f
1
Benzyl iodide and 2a were used: 0.16 g (52% yields); H
NMR (300 MHz, CDCl3): d 0.59 (s, 3H), 1.32 (s, 3H), 1.37
(d, J = 9.9 Hz, 1H), 2.05–2.10 (m, 1H), 2.46 (s, 3H), 2.50–
2.69 (m, 2H), 2.77 (t, J = 5.7 Hz, 1H), 3.28–3.32 (m, 1H),
3.72 (dd, J = 13.8, 3.6 Hz, 1H), 4.12 (s, 2H), 7.18–7.33
(m, 11H), 7.83 (d, J = 7.8 Hz, 1H); 13C NMR (CDCl3): d
15.25, 20.84, 26.24, 28.19, 32.59, 38.55, 41.14, 42.48,
45.92, 46.99, 116.00, 125.80, 126.56, 128.25, 128.31,
128.65, 129.29, 132.66, 133.47, 139.82, 140.98, 142.84,
148.92, 149.53, 159.12, 166.48; ESI-MS m/z: 451
(M+ + H).
3.12. Ligand 2g
(Iodomethyl)trimethylsilane and 2a were used: 0.15 g
(47% yields); 1H NMR (300 MHz, CDCl3): d 0.09 (s,
9H), 0.12 (s, 9H), 0.64 (s, 3H), 1.34 (d, J = 9.9 Hz, 1H),
1.40 (s, 3H), 1.51–1.57 (m, 2H), 2.16–2.20 (m, 2H), 2.33
(s, 3H), 2.48–2.55 (m, 2H), 2.72–2.77 (m, 1H), 3.14–3.19
(m, 1H), 7.18 (d, J = 8.1 Hz, 1H), 7.72 (d, J = 7.5 Hz,
1H); 13C NMR (CDCl3): d ꢀ1.47, ꢀ0.36, 15.35, 17.28,
20.99, 26.59, 28.33, 28.48, 40.20, 41.49, 46.82, 47.05,
115.32, 116.11, 131.69, 133.03, 141.49, 146.97, 149.13,
161.72; ESI-MS m/z: 443 (M+ + H).
3.8. Ligand 2c
2-Iodopropane and 2a were used: 0.11 g (50% yields); 1H
NMR (300 MHz, CDCl3): d 0.64 (s, 3H), 0.87 (d,
J = 6.9 Hz, 3H), 1.24 (d, J = 6.9 Hz, 3H), 1.39 (d,
J = 9.6 Hz, 1H), 1.42 (s, 3H), 2.35–2.41 (m, 1H), 2.51 (s,
3H), 2.55–2.62 (m, 1H), 2.68–2.77 (m, 2H), 2.91–2.94 (m,
1H), 6.92 (s, 1H), 7.26 (d, J = 7.8 Hz, 1H), 7.84 (d,
J = 7.8 Hz, 1H); 13C NMR (CDCl3): d 17.38, 20.37,