1532
Z. Han et al. / Tetrahedron: Asymmetry 21 (2010) 1529–1533
lowed by 6 mL DIPEA. The reaction mixture was degassed thrice
through freeze-pump-thaw cycles, and was stirred at 80 °C for
24 h. After cooling to room temperature, the mixture was evapo-
rated to dryness, and the residue was subjected to column chroma-
tography with petroleum ether/EtOAc/Et3N (10:1:0.3–2:1:0.03) as
the eluent to afford compound 6 (2.31 g) as a foamy solid in 85%
yield. Mp = 76–78 °C; 1H NMR (300 MHz, CDCl3) d = 7.89–7.85
(m, 1H), 7.78–7.71 (m, 2H), 7.59–7.53 (m, 2H), 7.49–7.28 (m,
7H), 7.00–6.94 (m, 1H), 6.80–6.74 (m, 2H), 6.33 (dt, J = 10.8 Hz,
2.4 Hz, 1H), 3.26–3.14 (m, 1H), 3.04–2.82 (m, 3H), 2.72–2.55 (m,
2H), 2.31–2.16 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3)
d = 169.8, 150.4 (d, J = 13.0 Hz), 147.7, 142.5 (d, J = 98.9 Hz),
135.0, 133.2 (d, J = 103.8 Hz), 131.5, 131.4, 131.3, 131.2, 131.2,
131.1, 130.3, 130.3, 130.0, 128.7, 128.1, 127.9, 127.7, 127.6,
127.1, 127.0, 127.0, 125.2, 64.0 (d, J = 10.4 Hz), 40.7 (d, J = 7.8 Hz),
36.8, 32.9 (d, J = 16.4 Hz), 28.0 ppm; 31P NMR (121 MHz, CDCl3)
the residue was purified by column chromatography on silica gel
with petroleum ether/CH2Cl2 (2:1–1:1) as the eluent to afford the
complex (S)-7 (212 mg) as an orange powder in 86% yield.
Mp = 193–195 °C; ½a D20
ꢂ
¼ þ1:3 (c 0.50, CHCl3); 1H NMR (300 MHz,
CDCl3) d = 9.42 (d, J = 8.7 Hz, 1H), 7.99 (t, J = 7.5 Hz, 1H), 7.76–
7.63 (m, 13H), 7.51 (s, 7H), 7.19–7.11 (m, 1H), 7.05–6.97 (m, 3H),
6.73–6.68 (m, 2H), 4.98–4.91 (m, 1H), 4.71–4.67 (m, 1H), 4.47–
4.39 (m, 1H), 3.26–3.21 (m, 1H), 3.08–2.99 (m, 1H), 2.84–2.31
(m, 10H), 2.08–1.63 (m, 5H) ppm; 13C NMR (75 MHz, CDCl3)
d = 171.6, 161.2 (q, J = 49.5 Hz), 145.4, 143.6 (d, J = 5.6 Hz), 137.3,
134.8, 134.5, 133.0 (d, J = 13.4 Hz), 132.3 (d, J = 2.4 Hz), 131.8 (d,
J = 2.5 Hz), 131.3, 131.2, 131.1, 130.4, 130.0, 129.8, 129.7, 129.1
(m), 128.7 (m), 128.4, 128.3, 128.2, 127.9, 127.3, 127.2, 126.5,
126.3, 125.5, 124.8, 122.7, 119.1, 117.4 (m), 88.8 (d, J = 8.7 Hz),
85.3 (d, J = 15.0 Hz), 66.8, 66.6, 65.6, 64.8, 38.5 (d, J = 4.7 Hz), 35.5
(d, J = 4.5 Hz), 34.6, 34.2, 34.0, 31.9, 29.7, 29.6 (m), 29.2, 27.0 (d,
J = 2.6 Hz) ppm; 31P NMR (121 MHz, CDCl3) d = 17.50 (s) ppm; 19F
d = 25.16 (s) ppm; IR (KBr pellet)
m 3053, 2963, 2925, 1592, 1499,
1437, 1426, 1406, 1188, 1119, 1107, 1030, 788, 753, 725, 696,
NMR (282 MHz, CDCl3) d = ꢀ62.80 (s) ppm; IR (film)
m 2925,
597, 568, 545, 527, 418 cmꢀ1; HRMS (MALDI) m/z: calcd for
1684, 1653, 1558, 1521, 1457, 1353, 1278, 1161, 1124, 886, 777,
C
C
28H25F3NOP: 422.1668, found: 422.1665 [M+H+]. Anal. Calcd for
28H24F3NOP: C, 79.79; H, 5.74; N, 3.32. Found: C, 79.62; H, 5.45;
757, 682 cmꢀ1; HRMS (MALDI) m/z: calcd for C36H36NP191Ir:
704.2186, found: 704.2162 [MꢀBArF]+. Anal. Calcd for C68H48BF24
-
N, 3.06. The resolution of rac-6 was performed with semi-prepara-
tive liquid chromatography on a ChiralPak AD-H (2 cm ꢁ 25 cm)
column. Conditions: hexane/iPrOH = 90:10, flow rate: 12 mL/min,
wavelength 254 nm; 40 mg/mL 6 in ethanol, injection volume:
IrNP: C, 52.05; H, 3.08; N, 0.89. Found: C, 51.67; H, 3.15; N, 1.12.
X-ray crystallographic data for (S)-7,
C68H48BF24IrNP, M =
1569.05. Crystal (0.327 ꢁ 0.265 ꢁ 0.230 mm3) was measured on a
Bruker Smart CCD area detector at 293(2) K using Mo-Ka radiation
4 mL. tR = 21.3 min ((S)-6), tR = 36.3 min ((R)-6). (S)-6
½
a 2D0
ꢂ
¼
(k = 0.71073 Å). The integration of the data yielded a total of 20,058
reflections to a maximum 2h value of 27.00° of which 14,000 were
independent. The structure was solved by direct method and
refined with the SHELXTL-97 software package using monoclinic
space group C2, with a = 19.2708(12) Å, b = 19.0997(12) Å, c =
þ32:4 (c = 0.53, CHCl3); (R)-6 ½a D20
¼ ꢀ36:1 (c = 0.66, CHCl3).
ꢂ
4.6. (S)-2-Diphenylphosphinospiro[2-cyclopentene-1,30-
[3H]cyclopenta[b] quinoline], 20,30-dihydro 1
18.4687(11) Å;
a = 90, b = 95.7260(10), c
= 90°; V = 6763.8(7) Å3;
A mixture of 200 mg (0.48 mmol) (S)-6, 10 mL benzene, and
0.59 mL (7.1 mmol) pyridine was degassed thrice through freeze-
pump-thaw cycles. The mixture was then cooled to 0 °C and
0.24 mL (2.4 mmol) HSiCl3 was added. The reaction mixture was
stirred for 0.5 h at 0 °C, and then refluxed for 24 h. After cooling
the mixture to room temperature, degassed saturated sodium
bicarbonate solution was added to quench the reaction. The result-
ing mixture was extracted with degassed diethyl ether, and the or-
ganic layers were combined and filtered through Celite. The filtrate
was evaporated in vacuo, and the residue was purified on silica gel
column chromatography eluting with petroleum ether and EtOAc
(100:1–50:1), to afford 1 (81 mg) as a colorless oil in 42% yield.
q
calcd = 1.541 g/cm3, Z = 4, Rint = 0.0547. Goodness of Fit indica-
tor = 0.927, Final R1 = 0.0500, wR2 = 0.1133 on F2 for observed data,
Pmax, Pmin = 1.345, ꢀ0.489 e Åꢀ3; Absolute structure parameter =
ꢀ0.002(5). CCDC 767885 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
4.8. General procedure for the asymmetric hydrogenation of
alkenes and imines
Ir complex (S)-7 (0.0015 mmol) and the alkene or imine
(0.15 mmol) were dissolved in the reaction solvent (DCM and
DME for alkenes and imines, respectively) under argon. The solu-
tion was transferred to a stainless steel autoclave under nitrogen
atmosphere, and then sealed. After purging with hydrogen for four
times, the H2 pressure inside the autoclave was adjusted to 50 bar.
After stirring at room temperature for 24 h, H2 was released in
hood. The conversion was determined by 1H NMR or GC analysis
of an aliquot from the crude reaction mixture. The samples used
for chiral HPLC determination of ee values were obtained after fil-
tration of the reaction mixture through a pad of silica gel column.
½
a 2D0
ꢂ
¼ ꢀ88:9 (c 0.65, CHCl3); 1H NMR (300 MHz, CDCl3) d = 7.94
(d, J = 8.4 Hz, 1H), 7.66–7.54 (m, 3H), 7.42–7.27 (m, 6H), 7.17 (td,
J = 8.1 Hz, 2.1 Hz, 2H), 7.02–6.95 (m, 3H), 5.78–5.75 (m, 1H),
3.16–3.08 (m, 1H), 3.00–2.80 (m, 2H), 2.67–2.43 (m, 3H), 2.25–
2.07 (m, 2H) ppm; 13C NMR (100 MHz, CDCl3) d = 170.9, 148.1,
146.8, 146.6, 141.8, 136.8, 136.7, 135.64, 135.56, 135.0, 133.9,
133.8, 133.7, 133.6, 130.0, 129.1, 128.4, 128.14, 128.07, 127.9,
127.65, 127.60, 127.5, 127.4, 127.2, 125.2, 64.8, 64.6, 39.4, 37.4,
32.9, 28.52, 28.47 ppm; 31P NMR (121 MHz, CDCl3) d = ꢀ22.77 (s)
ppm; HRMS (MALDI) m/z: calcd for C28H25F3NOP: 422.1668, found:
422.1667 [M+O+H+].
4.8.1. 1,2-Diphenyl-propane 9
4.7. (S)-2-Diphenylphosphinylspiro[2-cyclopentene-1,30-[3H]-
33% conversion, 48% ee. The enantiomeric excess was deter-
mined by HPLC on Chiralcel OJ column, hexane: isopropa-
nol = 99:1, flowing rate = 0.5 mL/min, UV detection at k = 254 nm,
tR = 17.1 min (minor), tR = 25.2 min (major).
cyclopenta[b]quinoline], 20,30-dihydro-( 4-1,5-cyclooctadiene)-
g
iridium(I)tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (S)-7
A
mixture of 54 mg (0.08 mmol) [Ir(cod)Cl]2 and 65 mg
(0.16 mmol) ligands (S)-1 in 6 mL degassed CH2Cl2 was refluxed
for 2 h. After cooling to room temperature, 185 mg (0.21 mmol)
NaBArF was added to the mixture. After stirring for 30 min, 5 mL
degassed water was added and the resulting mixture was vigor-
ously stirred for 1 h. The organic phase was separated and washed
with water. The solvent was removed by vacuum evaporation, and
4.8.2. N-Phenyl-1-phenylethylamine 11
>99% conversion, 58% ee. The enantiomeric excess was deter-
mined by HPLC on Chiralcel OD column (hexane: isopropanol = 90:
10, flowing rate = 0.5 mL/min, UV detection at k = 254 nm),
tR = 12.8 min (major), tR = 16.3 min (minor).