168
X.-Q. Hao et al. / Tetrahedron: Asymmetry 27 (2016) 163–170
127.2, 127.1, 126.6, 120.8, 67.8, 59.9, 20.7. HRMS (m/z, ESI+): m/z for
28H24N2S calcd 420.1660, found 421.1739 ([M+H]+).
4.2.4. 2-(2-(Phenylthio)naphthyl)imidazolines 8
C
The obtained 2-(2-bromophenyl)imidazoline 7 (1.23 mmol) was
dissolved in freshly distilled THF (6 mL) in a flame-dried Schlenk
tube at room temperature under a nitrogen atmosphere. The solu-
tion was cooled to À78 °C, then titrated n-BuLi (2.5 M in pentane,
0.98 mL, 2.5 mmol) was added dropwise by syringe. After the reac-
tion mixture was stirred for 30 min at À78 °C, a THF solution of
diphenyl disulfide (402 mg, 1.85 mL) was added and the whole
solution was stirred for 3 h. The reaction mixture was brought to
room temperature and treated with 10% NaOH. The organic layer
was extracted with EtOAc and the organic layer was washed with
brine and dried over MgSO4. After evaporation of the solvent, the
residue was purified by silica gel column chromatography
(EtOAc/ petroleum ether = 1/2) to give the corresponding product 8.
4.2.2.4. (S)-2-(2-(Isopropylthio)phenyl)-4-phenyl-1-(p-tolyl)-4,
5-dihydro-1H-imidazole 4d.
Yield: 54%, yellow oil,
[a
]
D
20 = À64 (c 0.1, CH2Cl2). TLC: Rf = 0.2 (petroleum ether/ethyl
acetate = 2:1). 1H NMR (400 MHz, CDCl3): d 7.54–7.50 (m, 2H),
7.47 (dd, J = 7.5, 1.2 Hz, 1H), 7.39–7.20 (m, 7H), 6.87 (d, J = 8.2 Hz,
2H), 6.63–6.58 (m, 2H), 5.39–5.32 (m, 1H), 4.42–4.34 (m, 1H),
3.96 (t, J = 9.2 Hz, 1H), 3.41 (dt, J = 13.3, 6.7 Hz, 1H), 2.19 (s, 3H),
1.18 (dd, J = 10.9, 6.7 Hz, 6H). 13C NMR (101 MHz, CDCl3) d 161.6,
144.0, 138.6, 135.5, 134.77, 132.3, 131.7, 130.0, 129.7, 129.1,
128.5, 127.1, 126.5, 120.3, 67.7, 59.5, 38.0, 22.99, 22.95, 20.7.
HRMS (m/z, ESI+): m/z for for C28H24N2S calcd 386.1817, found
387.1895 ([M+H]+).
4.2.4.1. (S)-4-Isopropyl-2-(1-(phenylthio)naphthalen-2-yl)-1-p-
4.2.3. 2-(2-Bromonaphthyl)imidazolines 7
tolyl-4,5-dihydro-1H-imidazole 8a.
Yield: 40%; yellow solid,
The obtained amido alcohol 6 (1.0 mmol) was added to a 25 mL
round bottom flask and refluxed in thionyl chloride (2.2 mL,
30 mmol) for 12 h. Excess thionyl chloride was then evaporated.
The residue was dissolved in dry diethyl ether and filtered to
remove insoluble impurities. To this solution was added dry tri-
ethylamine (0.8 mL, 6.0 mmol), followed by arylamine (1.2 mmol).
After stirring for 12 h at room temperature, 10% NaOH (20 mL) was
added and stirred for another 6 h. The aqueous portion was
extracted with dichloromethane and the organic layer was washed
with brine, dried over MgSO4, and evaporated. The crude product
was purified by silica gel column chromatography eluting with
EtOAc/petroleum ether (1/2) to provide desired product 7.
mp: 119–120 °C, [
a]
D
20 = À4 (c 0.41, CHCl3). TLC: Rf = 0.2 (petroleum
ether/ethyl acetate = 2:1). 1H NMR (400 MHz, CDCl3): d (ppm) 8.24
(d, J = 8.0 Hz, 1H, BinaphH), 7.96 (d, J = 8.0 Hz, 1H, BinaphH), 7.85
(d, J = 8.0 Hz, 1H, BinaphH), 7.71 (d, J = 8.0 Hz, 1H, BinaphH),
7.49–7.38 (m, 2H, BinaphH), 7.02–6.94 (m, 3H, PhH), 6.86–6.84
(m, 2H, PhH), 6.74 (d, J = 8.0 Hz, 2H, NArH), 6.56 (d, J = 8.0 Hz, 2H,
NArH), 4.11–3.97 (m, 2H, NCHPri and NCHH), 3.75 (m, 1H, NCHH),
2.13 (s, 3H, CH3), 1.93–1.88 (m, 1H, CH(CH3)2), 1.01 (d, J = 8.0 Hz,
3H, CH(CH3)2), 0.96 (d, J = 8.0 Hz, 3H, CH(CH3)2). 13C NMR
(100 MHz, CDCl3): d (ppm) 160.9, 138.5, 137.5, 134.4, 134.2,
132.0, 130.5, 129.2, 128.5, 127.4, 127.2, 127.0, 126.9, 124.9,
120.2, 54.0, 33.0, 20.6, 19.0, 18.2. HRMS (m/z, ESI+): m/z for
C
29H28N2S calcd 436.1973, found 437.2051 ([M+H]+).
4.2.3.1. (S)-2-(1-Bromonaphthalen-2-yl)-4-isopropyl-1-(p-tolyl)-
4,5-dihydro-1H-imidazole 7a.
Yield: 72%; yellow oil.
4.2.4.2. (S)-4-tert-Butyl-2-(1-(phenylthio)naphthalen-2-yl)-1-p-
tolyl-4,5-dihydro-1H-imidazole 8b. Yield: 33%, yellow solid,
mp: 66–68 °C, [
20 = +31 (c 0.53, CHCl3). TLC: Rf = 0.2 (petroleum
[
a D
]
20 = À49 (c 0.22, CHCl3). 1H NMR (400 MHz, CDCl3): d (ppm) 8.23
(d, J = 8.2 Hz, 1H, NaphthaleneH), 7.81–7.78 (m, 2H, NaphthaleneH),
7.56–7.48 (m, 3H, NaphthaleneH), 6.80 (d, J = 8.2 Hz, 2H, NArH),
6.60 (d, J = 8.5 Hz, 2H, NArH), 4.18–4.12 (m, 1H, NCHPri), 4.06–4.02
(appt, J = 9.6 Hz, 1H, NCHH), 3.82–3.78 (appt, J = 8.8 Hz, 1H, NCHH),
2.12 (s, 3H, CH3), 2.05–1.99 (m, 1H, CH(CH3)2), 1.12 (d, J = 6.8 Hz,
3H, CH(CH3)2), 1.07 (d, J = 6.8 Hz, 3H, CH(CH3)2). 13C NMR (100 MHz,
CDCl3): d (ppm) 160.6, 138.5, 134.4, 132.2, 132.1 (2C), 129.3, 128.3,
128.1, 127.8, 127.7, 127.3, 127.0, 123.0, 119.6, 70.4, 54.0, 33.1, 20.6,
19.1, 18.4. MS (m/z, ESI+): 407 (M+H).
a]
D
ether/ethyl acetate = 2:1). 1H NMR (400 MHz, CDCl3): d (ppm)
8.24 (d, J = 8.4 Hz, 1H, BinaphH), 7.97 (d, J = 8.4 Hz, 1H, BinaphH),
7.86 (d, J = 8.0 Hz, 1H, BinaphH), 7.72 (d, J = 8.4 Hz, 1H, BinaphH),
7.49–7.45 (m, 1H, BinaphH), 7.42–7.37 (m, 1H, BinaphH), 7.02–
6.96 (m, 3H, PhH), 6.83–6.80 (m, 2H, PhH), 6.75 (d, J = 8.3 Hz, 2H,
NArH), 6.59 (d, J = 8.2 Hz, 2H, NArH), 3.97 (m, 2H, NCHBut and
NCHH), 3.81 (m, 1H, NCHH), 2.12 (s, 3H, CH3), 0.97 (s, 9H, C
(CH3)3). 13C NMR (100 MHz, CDCl3): d (ppm) 161.1, 138.5, 137.6,
134.4, 134.3, 132.2, 130.5, 129.2, 128.6, 128.5, 127.5, 127.0,
126.9, 124.8, 120.5, 52.9, 34.2, 26.2, 20.6. HRMS (m/z, ESI+): m/z
for C30H30N2S calcd 450.2130, found 451.2205 ([M+H]+).
4.2.3.2. (S)-2-(1-Bromonaphthalen-2-yl)-4-(tert-butyl)-1-(p-tolyl)-
4,5-dihydro-1H-imidazole 7b.
Yield: 60%; yellow oil.
[a]D
20 = À14 (c 0.19, CHCl3). 1H NMR (400 MHz, CDCl3): d (ppm) 8.23
(d, J = 8.2 Hz, 1H, NaphthaleneH), 7.80–7.77 (m, 2H, NaphthaleneH),
7.56–7.48 (m, 3H, NaphthaleneH), 6.81 (d, J = 8.3 Hz, 2H, NArH), 6.61
(d, J = 8.4 Hz, 2H, NArH), 4.11–3.97 (m, 2H, NCHH and NCHBut), 3.86–
3.82 (appt, J = 8.6 Hz, 1H, NCHH), 2.12 (s, 3H, CH3), 1.08 (s, 9H, C
(CH3)3). 13C NMR (100 MHz, CDCl3): d (ppm) 160.6, 138.5, 134.4,
132.3, 132.2, 129.3, 128.2, 128.1, 127.7, 127.3, 127.1, 123.0, 119.8,
74.2, 52.8, 34.4, 26.3, 20.6. MS (m/z, ESI+): 422 (M+H).
4.2.4.3. (S)-4-Phenyl-2-(1-(phenylthio)naphthalen-2-yl)-1-p-tolyl-
4,5-dihydro-1H-imidazole 8c.
Yield: 27%, yellow solid, mp:
77–78 °C, [a D
]
20 = À108 (c 0.65, CHCl3). TLC: Rf = 0.2 (petroleum ether/
ethyl acetate = 2:1). 1H NMR (400 MHz, CDCl3): d (ppm) 8.27 (d,
J = 8.4 Hz, 1H, BinaphH), 8.02 (d, J = 8.4 Hz, 1H, BinaphH), 7.88 (d,
J = 8.0 Hz, 1H, BinaphH), 7.82 (d, J = 8.4 Hz, 1H, BinaphH), 7.51–7.47
(m, 1H, BinaphH), 7.44–7.40 (m, 1H, BinaphH), 7.31–7.22 (m, 5H
CHPhH), 7.03–6.99 (m, 3H, SPhH), 6.86 (d, J = 7.2 Hz, 2H, SPhH), 6.76
(d, J = 8.0 Hz, 2H, NArH), 6.58 (d, J = 8.4 Hz, 2H, NArH), 5.36–5.31
(m, 1H, CHPh), 4.32–4.31 (m, 1H, NCHH), 4.0 (m, 1H, CHH), 2.12
(s, 3H, CH3). 13C NMR (100 MHz, CDCl3): d (ppm) 162.3, 143.8, 138.0,
137.4, 132.5, 130.7, 129.3, 128.7, 128.6, 128.4, 127.6, 127.1, 126.9,
125.0, 120.4, 59.6, 29.7, 20.7. HRMS (m/z, ESI+): m/z for C32H26N2S calcd
470.1817, found 471.1891 ([M+H]+).
4.2.3.3. 2-(1-Bromonaphthalen-2-yl)-4-phenyl-1-(p-tolyl)-4,5-
dihydro-1H-imidazole 7c.
Yield: 47%; white solid. mp:
119–120 [
a
]
D
20 = À156 (c 0.11, CHCl3). 1H NMR (400 MHz, CDCl3):
d (ppm) 8.23 (d, J = 8.2 Hz, 1H, NaphthaleneH), 7.83–7.79 (m, 2H,
NaphthaleneH), 7.58–7.49 (m, 5H, PhH), 7.39–7.35 (m, 2H, Naph-
thaleneH), 7.30–7.25 (m, 1H, NaphthaleneH), 6.80 (d, J = 8.3 Hz,
2H, NArH), 6.62 (d, J = 8.5 Hz, 2H, NArH), 5.44–5.39 (m, 1H,
NCHPh), 4.44–4.39 (t, J = 9.8 Hz, 1H, NCHH), 4.05–4.00 (t,
J = 9.3 Hz, 1H, NCHH), 2.12 (s, 3H, CH3). 13C NMR (100 MHz, CDCl3):
d (ppm) 161.9, 143.8, 138.1, 134.5, 132.7, 132.1, 131.8, 129.3,
128.7, 128.3, 128.2, 127.9, 127.7, 127.5, 127.3, 127.1, 126.9,
123.1, 120.0, 67.8, 59.5, 20.7. MS (m/z, ESI+): 442 (M+H).
4.3. General procedure for the asymmetric allylic alkylation
To a flame-dried Schlenk tube were added [Pd(g
3-C3H5)Cl]2
(2.3 mg, 0.013 mmol) and ligand 4c (9.65 mg, 0.025 mmol) under
an argon atmosphere, followed by the addition of CH2Cl2 (1 mL).