M. Sako et al. / Tetrahedron: Asymmetry 26 (2015) 613–616
615
the central line of triplet for CDCl3 at 77 ppm. Optical rotations
were measured with JASCO P-1030 polarimeter. HPLC analyses
were performed on a JASCO HPLC system (JASCO PU 980 pump
and UV-975 UV/Vis detector) using a mixture of hexane and 2-pro-
panol as eluents. Column chromatography on SiO2 was performed
2H), 4.99 (s, 4H), 3.31 (s, 6H). The enantiomeric excess was deter-
mined by HPLC with a Daicel Chiralpak AS-H column (hexane/2-
propanol = 7:1, k = 235 nm, flow rate = 1.0 mL/min); tR (major
enantiomer) = 16.5 min, tR (minor enantiomer) = 27.9 min, 83% ee.
with Kishida Silica Gel (63–200
lm). Commercially available
4.6. (S)-7,70-Bis((2-methoxyethoxy)methoxy)-1,10-bi-2-naphthol
organic and inorganic compounds were used without further
purification. (Ra,S,S)-1, 2b, 2d, 2h, 2i, and 2j were prepared follow-
ing the reported procedures.4o,12 Products 3a, 3b, 3d, 3e, 3f, 3g, 3h,
3i, and 3j were identical in all respects with the data reported in
the literature.4n,13 Absolute configurations were assigned by
comparison of the specific rotation reported in the literature.4n,13
3c
Reaction time: 48 h; reaction temperature: 50 °C; 65% yield, yel-
low oil; [a]D
22 = +61.9 (c 0.7, CHCl3, 63% ee); 1H NMR (400 MHz,
CDCl3): d 7.88 (d, J = 9.2 Hz, 2H), 7.80 (d, J = 8.7 Hz, 2H), 7.26 (s, 2H),
7.23 (d, J = 9.2 Hz, 2H), 7.16 (dd, J = 8.7, 2.3 Hz, 2H), 6.71 (d,
J = 2.3 Hz, 2H), 5.15 (s, 2H), 5.10 (s, 4H), 3.70–3.62 (m, 4H), 3.45–
3.34 (m, 4H), 3.28 (s, 6H); 13C NMR (100 MHz, CDCl3): d 156.4 (C),
153.3 (C), 134.6 (C), 131.1 (CH), 130.0 (CH), 125.4 (C), 116.0 (CH),
115.8 (CH), 110.2 (C), 107.9 (CH), 93.4 (CH2), 71.4 (CH2), 67.5 (CH2),
59.0 (CH3); HRMS (ESI) calcd for C28H30NaO8, m/z = 517.1838
(M+Na)+, found m/z = 517.1826; IR (KBr): v 3390, 3058, 2931, 1621,
1512, 1203, 1159, 1019, 982, 834 cmꢀ1. The enantiomeric excess
was determined by HPLC with a Daicel Chiralpak AS-H column (hex-
ane/2-propanol = 4:1, k = 220 nm, flow rate = 1.0 mL/min); tR (major
enantiomer) = 22.0 min, tR (minor enantiomer) = 30.1 min, 63% ee.
4.2. Preparation of 7-((2-methoxyethoxy)methoxy)-2-naphthol
2c
To a solution of 2,7-dihydroxynaphthalene (961 mg, 6.0 mmol)
i
in CH2Cl2 (30 mL) were added Pr2NEt (1.15 mL, 6.6 mmol) and
MEMCl (0.75 mL, 6.6 mmol) at 0 °C. The mixture was warmed to
rt and then stirred for 24 h. After the reaction was completed,
water was added to the reaction mixture and the solution was
extracted with CH2Cl2. The organic layer was washed with brine,
dried over Na2SO4, and evaporated in vacuo. After the purification
via SiO2 column chromatography (hexane/acetone = 3:1), the
desired product was obtained as a yellow oil (675 mg, 45%). 1H
4.7. (S)-7,70-Bis(allyloxy)-1,10-bi-2-naphthol 3d4n
NMR (400 MHz, CDCl3):
d
7.67 (d, J = 8.7 Hz, 2H), 7.27 (d,
Reaction time: 48 h; reaction temperature: 50 °C; 78% yield;
D
J = 2.3 Hz, 1H), 7.05 (dd, J = 8.7, 2.3 Hz, 1H), 7.04 (d, J = 2.3 Hz,
1H), 6.96 (dd, J = 8.7, 2.3 Hz, 1H), 5.37 (s, 2H), 5.01 (s, 1H), 3.88–
3.86 (m, 2H), 3.60–3.57 (m, 2H), 3.39 (s, 3H); 13C NMR (100 MHz,
CDCl3): d 155.2 (C), 154.4 (C), 135.6 (C), 129.1 (CH), 129.1 (CH),
124.4 (C), 116.0 (CH), 115.9 (CH), 108.7 (CH), 108.4 (CH), 93.1
(CH2), 71.3 (CH2), 67.3 (CH2), 58.6 (CH3); HRMS (ESI) calcd for
[a]
22 = +177.6 (c 1.5, CHCl3, 85% ee); 1H NMR (400 MHz, CDCl3): d
7.85 (d, J = 8.7 Hz, 2H), 7.77 (d, J = 8.7 Hz, 2H), 7.20 (d, J = 8.7 Hz,
2H), 7.04 (dd, J = 8.7, 2.4 Hz, 2H), 6.47 (d, J = 2.4 Hz, 2H), 5.90–
5.80 (m, 2H), 5.15–5.09 (m, 4H), 5.06 (s, 2H), 4.32–4.21 (m, 4H).
The enantiomeric excess was determined by HPLC with a Daicel
Chiralpak IA column (hexane/2-propanol = 7:1, k = 235 nm, flow
rate = 1.0 mL/min); tR (major enantiomer) = 12.2 min, tR (minor
enantiomer) = 22.7 min, 85% ee.
C
14H16NaO4, m/z = 271.0946 [(M+Na)+], found m/z = 271.0938; IR
(KBr): v 3360, 3062, 2931, 1635, 1515, 1448, 1200, 1159, 1007,
833 cmꢀ1
.
4.8. (S)-7,70-Dibromo-1,10-bi-2-naphthol 3e13a
4.3. General procedure for coupling reactions of 2-naphthols 2
using (Ra,S,S)-1 in water
Reaction time: 48 h; reaction temperature: 70 °C; 85% yield;
D
[a]
21 = +129.1 (c 1.8, CHCl3, 73% ee); 1H NMR (400 MHz, CDCl3): d
A test tube was charged with a water (1 mL) heterogeneous
solution of coupling substrate 2 (0.2 mmol) under O2 (1 atm) atmo-
sphere. Vanadium catalyst (Ra,S,S)-1 (0.01 mmol, 5 mol %) was
added to the solution. The reaction mixture was stirred at 50 °C
for 2a, 2b, 2c, 2d, and 2f or 70 °C for 2e, 2g, 2h, 2i, and 2j until
the reaction had reached completion by monitoring with TLC anal-
ysis. The reaction mixture was then directly purified by silica gel
column chromatography eluting with ethyl acetate/hexane to give
the coupling product.
7.94 (d, J = 9.2 Hz, 2H), 7.76 (d, J = 8.7 Hz, 2H), 7.47 (dd, J = 8.7,
1.8 Hz, 2H), 7.38 (d, J = 9.2 Hz, 2H), 7.23 (d, J = 1.8 Hz, 2H), 5.05 (s,
2H). The enantiomeric excess was determined by HPLC with a
Daicel Chiralcel OD-H column (hexane/2-propanol = 9:1,
k = 235 nm,
flow
rate = 1.0 mL/min);
tR
(major
enan-
tiomer) = 15.9 min, tR (minor enantiomer) = 33.4 min, 73% ee.
4.9. (S)-7,70-Dimethoxy-1,10-bi-2-naphthol 3f4n
Reaction time: 48 h; reaction temperature: 50 °C; 87% yield;
D
4.4. (S)-1,10-Bi-2-naphthol 3a4n
[a
]
22 = +122.3 (c 1.0, CHCl3, 94% ee); 1H NMR (400 MHz, CDCl3):
d
7.86 (d, J = 8.7 Hz, 2H), 7.77 (d, J = 8.7 Hz, 2H), 7.21 (d,
Reaction time: 24 h; reaction temperature: 50 °C; 91% yield;
D
J = 8.7 Hz, 2H), 7.02 (dd, J = 8.7, 2.7 Hz, 2H), 6.47 (d, J = 2.7 Hz,
2H), 5.04 (s, 2H), 3.56 (s, 6H). The enantiomeric excess was
determined by HPLC with a Daicel Chiralpak AS-H column (hex-
ane/2-propanol = 9:1, k = 235 nm, flow rate = 1.0 mL/min); tR
(major enantiomer) = 18.8 min, tR (minor enantiomer) = 28.0 min,
94% ee.
[
a]
22 = ꢀ26.9 (c 1.0, THF, 80% ee); 1H NMR (400 MHz, CDCl3): d
7.98 (d, J = 8.7 Hz, 2H), 7.89 (d, J = 7.8 Hz, 2H), 7.43–7.34 (m, 4H),
7.31 (td, J = 7.8, 1.6 Hz, 2H), 7.15 (d, J = 8.2 Hz, 2H), 5.04 (s, 2H).
The enantiomeric excess was determined by HPLC with a Daicel
Chiralpak AS-H column (hexane/2-propanol = 7:1, k = 229 nm, flow
rate = 1.0 mL/min); tR (major enantiomer) = 9.8 min, tR (minor
enantiomer) = 15.1 min, 80% ee.
4.10. (S)-6,60-Dimethoxy-1,10-bi-2-naphthol 3g4n
4.5. (S)-7,70-Bis(methoxymethoxy)-1,10-bi-2-naphthol 3b4n
Reaction time: 48 h; reaction temperature: 50 °C; 78% yield;
Reaction time: 48 h; reaction temperature: 70 °C; 95% yield;
[a]D
20 = +25.6 (c 1.6, CHCl3, 63% ee); 1H NMR (400 MHz, CDCl3): d
7.83 (dd, J = 9.2, 1.8 Hz, 2H), 7.33 (dd, J = 9.2, 1.8 Hz, 2H), 7.19 (s,
2H), 7.05 (d, J = 9.2 Hz, 2H), 6.97 (dd, J = 9.2, 1.8 Hz, 2H), 4.94 (s,
2H), 3.89 (s, 6H). The enantiomeric excess was determined by HPLC
[a]
13 = +127.6 (c 1.1, CHCl3, 83% ee); 1H NMR (400 MHz, CDCl3): d
D
7.87 (d, J = 8.7 Hz, 2H), 7.79 (d, J = 8.7 Hz, 2H), 7.21 (d, J = 8.7 Hz,
2H), 7.14 (dd, J = 8.7, 2.3 Hz, 2H), 6.65 (d, J = 2.3 Hz, 2H), 5.08 (s,
with
a Daicel Chiralpak AS column (hexane/2-propanol = 4:1,