K. Tsubaki et al. / Tetrahedron: Asymmetry 14 (2003) 1393–1396
1395
hydroxide (6.0 M, 104 mL, 0.62 mol) was slowly added
to the organic layer at 0°C and stirred for 30 min.
White precipitate was collected by filtration and washed
with ether (150 mL, twice). The precipitate was added
to a mixed solvent of ether (1.5 L) and hydrochloric
acid solution. The organic layer was separated and
washed successively with 0.2 M aqueous sodium
hydroxide solution (500 mL, twice), 1.0 M hydrochloric
acid solution, and brine. After being dried over sodium
sulfate, the solvent was evaporated in vacuo to afford
crude 5 as a pale brown solid (107.1 g, 69% yield).
Crude 5 was directly used for the next step without
further purification. The characterization data have
been reported.6
Ether (50 mL) and petroleum ether (150 mL) were
added to the residue and allowed to stand for 2 days to
afford (aS)-7 as a white powder (47.9 g, 30% yield).
The residue obtained from the mother liquor was
purified by column chromatography (SiO2, 2 kg, n-hex-
ane/chloroform/ethyl acetate=6/3/1) to successively
gave (aS)-7 (17.1 g), a mixture (38.3 g) of (aS)-7 and
(aR)-7 and (aR)-7 (59.1 g). The mixture was again
purified by column chromatography to give (aS)-7
(13.2 g), a mixture (14.5 g), and (aR)-7 (7.8 g). The
third chromatography of the mixture (14.5 g) of (aS)-7
and (aR)-7 gave (aS)-7 (0.6 g), a mixture (1.1 g), and
(aR)-7 (12.9 g). Total yields of (aS)-7 and (aR)-7 were
75.8 g (45%) and 79.8 g (48%), respectively.
(aS)-7; mp=167–168°C (from ethyl acetate and n-hex-
ane); [h]2D0=−59 (c 1.04, CHCl3); IR (KBr) 3450, 2979,
3.3. 3,3%-Bis(benzyloxy)-1,1%-binaphthalene-2,2%-diol
( )-1
1
1772, 1712, 1621 cm−1; H NMR (200 MHz, CDCl3) l
0.4–1.0 (br, 6H), 1.39 (s, 18H), 4.2–4.4 (m, 2H), 5.0–5.3
(m, 2H), 5.29 (s, 4H), 7.15 (d, J=5.4 Hz, 4H), 7.25–
7.47 (m, 14H), 7.77 (d, J=7.8 Hz, 2H); MS (+APCI)
841.8 (M+1)+. Anal. calcd for C50H52N2O10: C, 71.41;
H, 6.23; N, 3.33. Found: C, 71.46; H, 6.20, N, 3.33.
To a solution of CuCl2 (107.6 g, 0.8 mol) in methanol
(600 mL), ( )-a-methylbenzylamine (129 mL, 1.0 mol)
was added under ice-bath cooling and stirred for 40
min (yellow–green solid was formed). A solution of
crude 5 (100 g, 0.4 mol) in dichloromethane (400 mL)
was added to the suspension at rt (the yellow–green
solid temporally dissolved and then large amount of
brown solid was deposited). The suspension was stirred
for 7 h. The solvent was evaporated under reduced
pressure and iced water (1 L) and conc. HCl (300 mL)
were successively added to the residue and extracted
with ethyl acetate (1.5 L). The organic layer was sepa-
rated, and the aqueous layer was washed with ethyl
acetate (1.5 L). The organic layer were combined and
washed with 1.0 M hydrochloric acid solution (1 L) and
brine. After being dried over sodium sulfate, the solvent
was evaporated in vacuo to afford crude ( )-1 as a pale
brown solid (99.4 g, 99% yield). Crude ( )-1 was
directly used for the next step without further purifica-
tion. A small part of the sample was subjected to the
further purification by column chromatography (SiO2,
n-hexane/ethyl acetate=5/1) to give an analytical sam-
ple. Mp 178–180°C (from ethyl acetate and ether); IR
(aR)-7; pale yellow viscous oil, [h]2D0=−24 (c 1.50,
CHCl3); IR (KBr) 3422, 2978, 1769, 1719, 1624 cm−1;
1H NMR (200 MHz, CDCl3) l 0.4–0.8 (br, 6H), 1.35 (s,
18H), 4.2–4.4 (m, 2H), 4.8–5.0 (m, 2H), 5.28 (s, 4H),
7.16 (d, J=4.0 Hz, 4H), 7.25–7.48 (m, 14H), 7.78 (d,
J=8.4 Hz, 2H); MS (+APCI) 841.8 (M+1)+. Anal.
calcd for C50H52N2O10: C, 71.41; H, 6.23; N, 3.33.
Found: C, 71.22; H, 6.29, N, 3.28.
3.5. (S)-3,3%-Bis(benzyloxy)-1,1%-binaphthalene-2,2%-diol
(S)-1
A solution of (aS)-7 (65.4 g, 77.8 mmol) in THF (460
mL) and aqueous sodium hydroxide (3.0 M, 78 mL,
0.23 mol) was stirred at 60°C for 11 h under an argon
atmosphere. The solvent was evaporated off (about 300
mL), ethyl acetate (650 mL) and water (650 mL) were
added to the residue and separated. The aqueous layer
was extracted with ethyl acetate (650 mL). The organic
layers were combined and washed successively with
water (500 mL), aqueous hydrochloric acid solution
(0.1 M, 500 mL), water (500 mL) and brine (100 m).
After being dried over sodium sulfate, the solvent was
evaporated in vacuo to give a residue as pale yellow
viscous oil. The residue was crystallized and triturated
with ether (25 mL) and n-hexane (45 mL) to give (S)-1
as a pale yellow powder (35.3 g, 91%). mp=131–133°C;
[h]D20=−56 (c 1.02, CHCl3), [h]2D0=−74 (c 1.81, THF)
for >99% ee, [lit.,3a [h]2D3=+22.0 (c 0.80, THF) 38% ee
R]; HPLC tR 21.7 min (S) (Chiralcel AS, i-PrOH/n-
hexane=20/80, 1.25 mL/min, u=254 nm). The first
aqueous layer was acidified with hydrochloric acid and
extracted with ethyl acetate (500 mL, twice). The
organic layer was washed successively with water (500
mL) and brine (100 m). After dried over sodium sulfate,
the solvent was evaporated in vacuo to give a residue as
a pale colorless viscous oil. The residue was crystallized
and triturated with n-hexane (20 mL) to give Boc-Ala-
OH as a white powder (23.3 g, 79%). [h]2D0=−26 (c 1.50,
AcOH) (pure Boc-Ala-OH, [h]2D0=−26 (c 1.78, AcOH)).
1
(CHCl3) 3532, 3067, 1463, 1445, 1380, 1011 cm−1; H
NMR (200 MHz, CDCl3) l 5.33 (s, 4H), 6.10 (s, 2H),
7.16 (d, J=4.8 Hz, 4H), 7.22–7.52 (m, 14H), 7.77 (d,
J=8.1 Hz, 2H); HRMS calcd for C34H26O4: 498.1831.
Found: 498.1816. Anal. calcd for C34H26O4: C, 81.91;
H, 5.26. Found: C, 81.67; H, 5.19.
3.4. 2-tert-Butoxycarbonylamino-propionic acid 3,3%-
bis(benzyloxy)-2%-(2-tert-butoxycarbonylamino-propionyl-
oxy)-1,1%-binaphthalenyl-2-yl ester. (aS)-7 and (aR)-7
To a solution of ( )-1 (99.0 g, 0.20 mol), Boc-Ala-OH
(94.0 g, 0.50 mol), and DMAP (1.0 g) in DMF (600
mL), WSC·HCl (114.4 g, 0.60 mol) was added portion-
wise under water-bath cooling and stirred for over
night. The reaction mixture was poured into the mixed
solvent of ether (1 L) and water (1.5 L). The aqueous
layer was extracted with ether (1 L). The organic layers
were combined and washed successively with aqueous
hydrochloric acid solution (0.1 M, 1 L), water (1 L,
twice), and brine. After being dried over sodium sulfate,
the solvent was evaporated in vacuo to give a residue.