Chiral 1,2,3,4-Tetrahydro-1-naphthylamine-Derived Phosphine-Phosphoramidite Ligand
UPDATES
(1H, m, NH), 5.26–5.27 (1H, m, CH), 6.64 (1H, d, J=
8.8 Hz, Ar-H), 6.89 (1H, m, Ar-H), 7.11–7.41 (20H, m, Ar-
H), 7.65 (1H, d, J=8.8 Hz, Ar-H), 7.82–7.89 (2H, m, Ar-H)
ppm; 13C NMR (100 MHz, CDCl3): d=16.6, 28.8, 31.7, 47.3
(t, J=23.0 Hz), 122.0, 122.6, 124.6 (d, J=7.0 Hz), 125.9 (d,
J=8.0 Hz), 127.0 (d, J=4.0 Hz), 127.6, 128.2, 128.3, 128.4,
128.5, 128.6, 128.7, 129.2, 130.0, 130.7, 130.8, 131.3, 132.8,
132.9, 133.4(d, J=19 Hz), 134.4 (d, J=20 Hz), 136.4, 136.9,
137.0, 138.2 (d, J=12 Hz), 142.4, 142.7, 147.5, 149.7;
31P NMR (162 MHz, CDCl3): d=À18.41 (d, J=52.5 Hz),
152.84 (d, J=52.5 Hz); HR-MS (EI): m/z=645.1979, calcd.
for C42H33NO2P2 [M+]: 645.1987.
Preparation of (R)-8-Diphenylphosphino-1,2,3,4-
tetrahydro-1-naphthylamine 3 [(Rc)-THNANH2]
To an ice-cold solution of 5.88 g (40 mmol) of (R)-1,2,3,4-
tetrahydro-1-naphthylamine 2 in 40 mL of Et2O were added
25 mL (40 mmol) of a 1.6M solution of n-BuLi in hexane
dropwise. The solution was stirred at 08C for 15 min, and
then 5.5 mL (44 mmol, 1.1 equiv.) of Me3SiCl were added
slowly. After 10 h, the solution was cooled to À258C, and
then 75 mL (120 mmol) of a 1.6M solution of n-BuLi in
hexane were added dropwise and the reaction mixture was
allowed to warm to room temperature within 5 h. The reac-
tion mixture was cooled to À258C again, and then a solution
of 8.82 g (40 mmol, 7.1 mL) of ClPPh2 in 40 mL of Et2O was
added within a period of 1 h. The reaction mixture was al-
lowed to warm to room temperature, and stirred at room
temperature overnight, and then cooled to 08C, upon which
a 1M solution of aqueous HCl (about 12 mL) was added
slowly. The organicphase was seperated and washed with
saturated aqueous NaHCO3 (40 mL2) and saturated aque-
ous NaCl (40 mL1), and dried over Na2SO4. The solvent
was removed and the residue was purified by column chro-
matography (SiO2, 2% Et3N, eluting with a mixture of hex-
anes/EtOAc/Et3N, 10/1/0.5). After removal of the volatile,
the resulting solid was recrystallized from n-hexane to give a
General Procedure for Asymmetric Hydrogenation
In
a
nitrogen-filled glovebox, Rh(COD)2BF4 (2.0 mg,
A
0.005 mmol) and (Rc,Ra)-1a (3.6 mg, 0.0055 mmol) were dis-
solved in degassed CH2Cl2 (1 mL) in a 5-mL vial. After stir-
ring at room temperature for 15 min, a solution of N-(1-phe-
nylethenyl)acetamide 4a (81 mg, 0.5 mmol, S/C 100:1) in
1 mL of degassed CH2Cl2 was added. The resulting mixture
was transferred to an autoclave, which was then charged
with H2 (10 atm). The hydrogenation was performed at
room temperature for 24 h. After carefully releasing the hy-
drogen gas, the reaction mixture was concentrated under re-
duced pressure. The residue was purified through a plug of
silica gel (eluting with a mixture of hexanes/EtOAc, 2/1) to
afford 5a. The enantiomeric excess was determined by chiral
GC.
1
light-yellow crystalline solid; yield: 6.83 g (52%). H NMR
(400 MHz, CDCl3): d=7.31–7.28 (8H, m, Ar-H), 7.25–7.22
(2H, m, Ar-H), 7.08–7.02 (2H, m, Ar-H), 6.80–6.77 (1H, m,
Ar-H), 4.64–4.63 (1H, m, ArCH), 2.85–2.76 (2H, m, Ar-
CH2), 2.00–1.86 (2H, m, CH2), 1.78–1.71 (2H, m, CH2), 1.65
(2H, s, N-H); 13C NMR (100 MHz, CDCl3): d=145.47,
137.66, 137.16, 137.07, 136.68, 136.62, 134.21, 134.01, 133.55,
133.36, 132.61, 130.93, 128.82, 128.73, 128.66, 128.59, 128.52,
126.87, 46.34, 31.48, 29.81, 17.18; 31P NMR (162 MHz,
CDCl3): d=À16.28; HR-MS (EI): m/z=331.1493, calcd. for
C22H22NP [M+]: 331.1490.
Acknowledgements
We are grateful for financial support from the National Natu-
ral Science Foundation of China (20472083).
Preparation of (Rc,Ra)-THNAPhos 1a
(Ra)-4-Chloro-3,5-dioxa-4-phosphacyclohepta[2,1-a’;3,4-a’]di- References
naphthalene (350.5 mg, 1.0 mmol) was dissolved in 4.0 mL
of dried CH2Cl2, and cooled to 08C. A solution of (Rc)-3
(331 mg, 1.0 mmol) and Et3N (303 mg, 3.0 mmol) in 4.0 mL
of CH2Cl2 was added to the above solution within 30 min.
The resulting mixture was left stirring at room temperature
overnight. After filtering off the precipitate, the filtrate was
collected and concentrated under reduced pressure. The res-
idue was purified by column chromatography to give
(Rc,Ra)-1a, as a crystalline solid; yield: 574 mg (89%);
1H NMR (400 MHz, CD2Cl2): d=7.85–7.80 (4H, m, Ar-H),
7.29–7.11 (18H, m, Ar-H), 6.95–6.94 (2H, m, Ar-H), 6.72
(1H, m, Ar-H), 5.35–5.34 (1H, m, Ar-CH), 3.35–3.30 (1H,
m, N-H), 2.71–2.14 (2H, m, Ar-CH2), 2.18–2.14 (1H, m,
CH2), 1.90–1.78 (3H, m, CH2); 13C NMR (100 MHz,
CD2Cl2): d=149.61, 147.89, 137.04, 133.98, 133.76, 133.57,
130.78, 130.13, 129.56, 128.64, 128.52, 128.45, 127.57, 126.79,
126.63, 126.18, 124.90, 124.79, 122.79, 122.08, 47.11, 33.34,
29.43, 17.07; 31P NMR (162 MHz, CD2Cl2): d=155.4, À18.8;
HR-MS (EI): m/z=645.1979, calcd. for C42H33NO2P2 [M+]:
645.1987.
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A
1H NMR (400 MHz, CDCl3): d=1.75–1.80 (2H, m, CH2),
1.97–2.05 (2H, m, CH2), 2.76–2.82 (2H, m, CH2), 3.34–3.38
Adv. Synth. Catal. 2008, 350, 1413 – 1418
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