N. Kurono et al.
Bull. Chem. Soc. Jpn. Vol. 86, No. 5 (2013)
581
dioxane, diglyme, DMF, pentane, CH2Cl2, and methanol were
purchased from Kanto Chemical Co., Inc. and used without
further purification. Li2CO3 was purchased from Aldrich Co.
and used as a 0.1 M aqueous solution. NMR spectra were
recorded on a JEOL JNM-ECS400 or LA400 (400 MHz for
1H NMR, 100 MHz for 13C NMR, 161.7 MHz for 31P NMR)
spectrometer. The chemical shifts were reported downfield
(SA,SP)-5a as yellow needles (8 mg, 8.6 ¯mol, 66% yield). Mp
(decomp) 153 °C; 1H NMR (400 MHz, THF-d8): ¤ 2.96 (m, 2H,
NHH), 3.63 (m, 2H, 2PhCH, partially overlapped to a peak of
THF), 4.98 (t, 2H, J = 8.3 Hz, NHH), 6.02 (d, 2H, J = 7.6 Hz,
aromatic H), 6.74 (t, 2H, J = 7.6 Hz, aromatic H), 6.97-7.58
(m and br, 32H, aromatic H), 7.75-8.89 (br, 2H, aromatic H);
31P NMR (161.7 MHz, THF-d8): ¤ 53.1 (s); HRMS (ESI+) m/z
calcd for C52H44LiN2O4P2102Ru: 931.1980 ([3a + Li]+); found:
931.1975.
The crystallographic data have been deposited with
Cambridge Crystallographic Data Centre: Deposition number
CCDC 910499. Copies of the data can be obtained free of
from the Cambridge Crystallographic Data Centre, 12, Union
Road, Cambridge, CB2 1EZ, U.K.; Fax: +44 1223 336033;
e-mail: deposit@ccdc.cam.ac.uk).
1
from TMS (¤ = 0) for H NMR. For 13C NMR, the chemical
shifts were reported on a scale relative to the solvent used as an
internal reference. Carbon multiplicity was assigned by DEPT
experiments. 31P NMR was carried out with phosphoric acid
as an external standard. Gas chromatography (GC) analysis was
conducted on a Shimadzu GC-17A or GC-2010 instrument
using helium carrier gas. Mass-spectrometric measurements
and elemental analysis were carried out at the Instrumental
Analysis Division, Equipment Measurement Center, Creative
Research Institution, Hokkaido University.
Isomerization of (SA,RP)-4b to the Equilibrium 4a/4b
Preparation of Ruthenium Complexes [Ru{(S)-phgly}2-
{(S)-biphep}] [(SA,SP)-4a] and [Ru{(S)-phgly}2{(R)-biphep}]
[(SA,RP)-4b].
Mixture.
A degassed 1,4-dioxane (0.5 mL) solution of
(SA,RP)-4b (9.2 mg, 10 ¯mol, 20 mM) was stirred and heated at
120 °C (oil bath temperature) for 3 h under argon atmosphere.
After cooling to room temperature, 31P NMR measurement of
the solution was carried out to estimate the ratio of (SA,SP)-4a/
(SA,RP)-4b. The data are listed in Table 1.
General Procedure of Asymmetric Cyanosilylation of
Benzaldehyde (1). Caution: (CH3)3SiCN must be used in a
well-ventilated hood due to its high toxicity.
A 50-mL Schlenk flask equipped with a Teflon-coated
magnetic stirring bar was filled with argon. (CH3)3SiCN (1.19 g,
12.0 mmol) and 0.10 M aqueous solution of Li2CO3 (10 ¯L,
1.0 ¯mol) were placed in the flask, and the mixture was stirred
for 30 min at 25 °C. To the pale yellow solution were added
(C2H5)2O (10 mL), a 20 mM-THF solution of (SA,SP)-4a (50
¯L, 1.0 ¯mol), and tetralin (0.97 g, 7.34 mmol) as an internal
standard for GC analysis. The resulting yellow solution was
cooled down to ¹78 °C. Then 1 (1.06 g, 10.0 mmol) was
charged into the flask, and the mixture was stirred for 12 h. The
product was identified in accordance with the literature,3a and
the yield and ee of the product were determined by GC analysis
(>99% yield, 96% ee). The ee of 2 was determined by GC
analysis: column, CP-Chirasil-Dex (0.32 mm i.d. © 25 m, df =
0.25 ¯m; Varian); column temp, 110 °C; injection temp, 220 °C;
retention time (tR) of (R)-2, 22.8 min (98.0%); tR of (S)-2,
22.3 min (2.0%).
[RuCl2(η6-C6H6)]2 (127 mg, 0.25 mmol) and
BIPHEP (262 mg, 0.51 mmol) were placed in a 50-mL Schlenk
flask. After the air in the flask was replaced with argon,
degassed DMF (10 mL) was added, and the mixture was heated
at 100 °C for 10 min with stirring to give a reddish brown
solution. After the solution was cooled to 25 °C, a degassed
methanol solution (10 mL) of sodium (S)-phenylglycinate (260
mg, 1.5 mmol) was added and the mixture was stirred for
12 h. After removal of the solvent under reduced pressure, the
residue was dissolved with ethyl acetate (80 mL). The solu-
tion was washed with water (100 mL © 3) and brine, and then
dried over MgSO4. After evaporation of the solvent, the crude
complex ((SA,SP)-4a:(SA,RP)-4b = 1:1.06 determined by 1H-
and 31P NMR measurement) was purified by silica gel column
chromatography (eluent: ethyl acetate to 1:9 methanol/ethyl
acetate, Rf of (SA,SP)-4a = 0.47-0.63 (eluent: ethyl acetate),
Rf of (SA,RP)-4b = 0.26-0.39 (eluent: ethyl acetate)). Each
complex was precipitated with a mixture of CH2Cl2 (2 mL)
and pentane (50 mL) to afford (SA,SP)-4a (light yellow powder,
187 mg, 40% yield) and (SA,RP)-4b (light yellow powder, 182
mg, 39% yield), respectively. (SA,SP)-4a: mp (decomp) 212 °C;
1H NMR (400 MHz, CDCl3): ¤ 2.60 (m, 2H, NHH), 3.31 (m,
2H, NHH), 3.74 (t, 2H, J = 8.3 Hz, 2PhCH), 6.03 (d, 2H, J =
6.8 Hz, aromatic H), 6.73-9.02 (m and br, 36H, aromatic H);
31P NMR (161.7 MHz, CDCl3): ¤ 51.4 (s); HRMS (ESI): m/z
calcd for C52H44N2O4P2Ru: 924.1834 ([M]+); found: 942.1826.
(SA,RP)-4b: mp (decomp) 210 °C; 1H NMR (400 MHz, CDCl3):
¤ 2.21 (br, 2H, NHH), 2.53 (br, 2H, NHH), 4.68 (br, 2H,
2PhCH), 5.93 (d, 2H, J = 6.8 Hz, aromatic H), 6.41-8.67 (m,
36H, aromatic H); 31P NMR (161.7 MHz, CDCl3): ¤ 50.7 (s);
HRMS (ESI): m/z calcd for C52H44N2O4P2Ru: 924.1834
([M]+); found: 942.1832.
This work was supported by a Grant-in-Aid from the Japan
Society for the Promotion of Science (JSPS: No. 24350042).
Supporting Information
Copies of the 1H and 31P NMR spectra of the Ru complexes
4 and the chiral GC charts of the compounds 2. This material
Preparation of Bimetallic Complex [Li(Ru{(S)-phgly}2-
{(S)-biphep})]Br [(SA,SP)-5a].
A THF solution of LiBr
References
(0.1 M, 150 ¯L, 15 ¯mol) was added to (SA,SP)-4a (12 mg, 13
¯mol) in a 20-mL Schlenk tube under an argon atmosphere.
The clear orange solution was stored at ambient temperature
for 10 h and at ¹11 °C (normal freezer) for 7 h. The precipitated
yellow solid was filtered and washed with a small amount of
cold THF followed by drying under reduced pressure to afford
1
Kurono, Nobuhito
