Y. Okuyama et al. / Tetrahedron: Asymmetry 16 (2005) 2551–2557
2555
4.2.3. 2-(2-Ethylphenylthio)benzaldehyde 4c. Obtained
128.15, 127.97, 127.54, 126.46, 126.19, 85.67, 80.28,
46.77, 45.56, 41.94, 37.91, 34.30, 29.95, 27.24, 23.41,
20.45. MS m/z: 382 (M+). HRMS calcd for C23H26OS2:
382.1425, found: 382.1443.
(1.70 g, 99%) as a light yellow oil. IR (film) cmꢀ1
:
1
1695, 1587, 1558, 845, 755, 655. H NMR (CDCl3): d
10.34 (s, 1H). 7.83 (dd, J = 1.7, 7.5 Hz, 1H), 7.18–7.38
(m, 6H), 6.84 (d, J = 7.6 Hz, 1H), 2.78 (dd, J = 7.6,
15.0 Hz, 2H), 1.18 (t, J = 7.5 Hz, 3H). 13C NMR
(CDCl3): d 191.18, 147.26, 142.40, 135.34, 133.84,
133.02, 132.31, 130.77, 129.39, 129.30, 128.68, 127.14,
125.35, 27.22, 15.18. MS m/z: 242 (M+). HRMS calcd
for C15H14OS: 242.0766, found: 242.0777.
4.3.2. (1R,3R,5R,8S)-11,11-Dimethyl-5-(2,6-dimethyl-
phenylthio)phenyl-4-oxa-6-thiatricyclo[6.2.1.0]undecane
7b. Obtained (215 mg, 97%) as a white solid, mp 117–
24
118 ꢁC (hexane–ether). ½aꢁD ¼ ꢀ10.0 (c 2.20, CHCl3).
1
IR (KBr) cmꢀ1: 1580, 768, 750. H NMR (CDCl3): d
7.59 (d, J = 7.7 Hz, 1H), 7.08–7.24 (m, 4H), 6.99 (t,
J = 7.6 Hz, 1H), 6.46 (d, J = 7.9 Hz, 1H), 6.21 (s,
1H), 3.89 (dd, J = 3.1 Hz, 7.9 Hz, 1H), 3.38 (d,
J = 14.2 Hz, 1H), 2.84 (d, J = 14.2 Hz, 1H), 2.39 (s,
6H), 2.06 (m, 1H), 1.72–1.84 (m, 3H), 1.58 (m, 1H),
1.51 (s, 3H), 1.03–1.13 (m, 2H), 0.98 (s, 3H). 13C
NMR (CDCl3): d 143.90, 136.75, 134.91, 130.93,
129.19, 128.64, 128.48, 127.09, 125.55, 125.26, 85.98,
79.67, 46.89, 45.63, 42.16, 38.06, 34.43, 29.93, 27.35,
23.49, 21.90, 20.51. MS m/z: 410 (M+). HRMS calcd
for C25H30OS2: 410.1738, found: 410.1711.
4.2.4.
2-(2-tert-Butylphenylthio)benzaldehyde
4d.
Obtained (1.77 g, 92%) as a light yellow oil. IR (film)
cmꢀ1: 1693, 1588, 1558, 845, 656. H NMR (CDCl3):
1
d 10.36 (s, 1H), 7.84 (dd, J = 1.7, 7.5 Hz, 1H), 7.54 (d,
J = 8.2 Hz, 1H), 7.16–7.38 (m, 5H), 6.80 (d,
J = 7.9 Hz, 1H), 1.52 (s, 9H). 13C NMR (CDCl3): d
191.08, 152.62, 144.00, 138.27, 133.80, 133.03, 131.92,
131.57, 129.42, 128.78, 127.23, 127.16, 125.13, 36.73,
30.79 · 3. MS m/z: 270 (M+). HRMS calcd for
C17H18OS: 270.1078, found: 270.1058.
4.2.5. 2-(1-Naphthylthio)benzaldehyde 4e. Obtained
(1.65 g, 88%) as a white solid, mp 83–84 ꢁC (hexane).
IR (KBr) cmꢀ1: 1673, 1588, 846, 759. 1H NMR
(CDCl3): d 10.40 (s, 1H), 8.27 (m, 1H), 7.75–7.96 (m,
4H), 7.46–7.56 (m, 3H), 7.14–7.25 (m, 2H), 6.67 (m,
1H). 13C NMR (CDCl3): d 191.24, 142.25, 134.46,
134.17, 133.90, 133.75, 132.88, 132.59, 130.31, 128.85,
128.60, 128.32, 127.27, 126.56, 125.95, 125.44, 125.08.
MS m/z: 264 (M+). HRMS calcd C17H12OS: 264.0609,
found: 264.0574.
4.3.3. (1R,3R,5R,8S)-11,11-Dimethyl-5-(2-ethylphenyl-
thio)phenyl-4-oxa-6-thiatricyclo[6.2.1.0]undecane 7c.
Obtained (217 mg, 98%) as a white solid, mp 70–72 ꢁC
22
(hexane–ether). ½aꢁD ¼ ꢀ27.95 (c 1.86, CHCl3). IR
1
(KBr) cmꢀ1: 1586, 748, 706. H NMR (CDCl3): d 7.66
(d, J = 7.8 Hz, 1H), 7.05–7.28 (m, 6H), 7.01 (d,
J = 7.8 Hz, 1H), 6.17 (s, 1H), 3.76 (dd, J = 3.0, 7.9 Hz,
1H), 3.29 (d, J = 14.3 Hz, 1H), 2.76–2.85 (m, 3H), 1.99
(m, 1H), 1.70–1.78 (m, 3H), 1.51 (m, 1H), 1.50 (s, 3H),
1.24 (t, J = 7.5 Hz, 3H), 1.00–1.09 (m, 2H), 0.95 (s,
3H). 13C NMR (CDCl3): d 144.84, 139.60 133.84,
133.19, 132.63, 131.28, 128.74, 128.65, 127.53, 127.48,
127.25, 126.61, 85.80, 80.24, 46.85, 45.61, 42.07, 38.03,
34.41, 30.05, 27.35, 27.12, 23.52, 20.55, 14.88. MS m/z:
410 (M+). HRMS calcd for C25H30OS2: 410.1738,
found: 410.1729.
4.2.6. 2-(2-Naphthylthio)benzaldehyde 4f.8b Obtained
as a white solid (1.84 g, 98%).
4.3. General procedure for preparations of chiral ligands
7a–f and 8a and b
4.3.4. (1R,3R,5R,8S)-5-(2-tert-Butylphenylthio)phenyl-
11,11-dimethyl-4-oxa-6-thiatricyclo[6.2.1.0]undecane 7d.
(1S)-(ꢀ)-10-Mercaptoisoborneol 1 (100 mg, 0.54 mmol)
or (1S)-(ꢀ)-10-mercaptoborneol 2 (100 mg, 0.54 mmol),
2-phenylthiobenzaldehyde 4a–d (0.60 mmol) or 2-naph-
thylthiobenzaldehyde 4e,f (0.60 mmol), p-toluenesulf-
onic acid monohydrate (20 mg, 0.11 mmol), and
benzene (8 mL), were placed in a flask equipped with a
Dean-Stark trap. The mixture was refluxed for 1–2 h.
The solvent was evaporated under a reduced pressure
and the residue purified by preparative TLC (hexane–
ether = 10:1) to give the corresponding products 7a–f
and 8a and b.
Obtained (196 mg, 83%) as a white solid, mp 100–
22
102 ꢁC (hexane–ether). ½aꢁD ¼ ꢀ39.45 (c 1.47, CHCl3).
1
IR (KBr) cmꢀ1: 1587, 759, 692. H NMR (CDCl3): d
7.65 (dd, J = 1.6, 7.7 Hz, 1H), 7.43 (dd, J = 1.4,
8.0 Hz, 1H), 7.11–7.35 (m, 4H), 7.03 (t, J = 7.3 Hz,
2H), 6.16 (s, 1H), 3.72 (dd, J = 3.1, 7.9 Hz, 1H), 3.28
(d, J = 14.2 Hz, 1H), 2.78 (d, J = 14.2 Hz, 1H), 1.99
(m, 1H), 1.69–1.77 (m, 3H), 1.58 (s, 9H), 1.15 (m, 1H),
1.50 (s, 3H), 0.96 (s, 3H), 0.92–1.11 (m, 2H). 13C
NMR (CDCl3): d 150.18, 139.67, 135.32, 135.03,
134.87, 131.99, 128.84, 127.52, 127.24, 126.93, 126.74,
126.46, 85.80, 80.38, 46.87, 45.63, 42.07, 38.04, 36.61,
34.44, 30.68 · 3, 30.04, 27.37, 23.52, 20.57. MS m/z:
438 (M+). HRMS calcd for C27H34OS2: 438.2051,
found: 438.2061.
4.3.1. (1R,3R,5R,8S)-11,11-Dimethyl-4-oxa-5-(2-phenyl-
thio)phenyl-6-thiatricyclo[6.2.1.0]undecane 7a. Obtained
24
(194 mg, 94%) as a colorless oil. ½aꢁD ¼ ꢀ55.2 (c 1.74,
CHCl3). IR (film) cmꢀ1: 1583, 691, 656. 1H NMR
(CDCl3): d 7.69 (d, J = 7.8 Hz, 1H), 7.16–7.43 (m, 8H),
6.20 (s, 1H), 3.75 (dd, J = 3.1, 8.1 Hz, 1H), 3.29 (d,
J = 14.3 Hz, 1H), 2.79 (d, J = 14.2 Hz, 1H), 2.01 (m,
1H), 1.68–1.78 (m, 3H), 1.54 (m, 1H), 1.50 (s, 3H),
1.00–1.02 (m, 2H), 0.96 (s, 3H). 13C NMR (CDCl3): d
140.45, 136.13, 132.74, 132.03, 130.10, 128.89, 128.76,
4.3.5. (1R,3R,5R,8S)-11,11-Dimethyl-5-(1-naphthyl-
thio)phenyl-4-oxa-6-thiatricyclo[6.2.1.0]undecane 7e.
Obtained (147 mg, 63%) as a white solid, mp 128–
22
130 ꢁC (hexane–ether). ½aꢁD ¼ ꢀ57.6 (c 1.18, CHCl3).