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S. Aragone`s et al. / Tetrahedron: Asymmetry 14 (2003) 1847–1856
organic solvent was then evaporated, and the crude was
purified by column chromatography to furnish the
desired hydroxyazide.
4.10. (S)-2-O-Allyl-1-benzyl-but-3-en-1,2-diol 5
The general method for the allylation reaction was
applied, starting from 3 (1.80 g, 5.45 mmol), NaH
(60%, 654 mg, 16.4 mmol), allyl bromide (1.40 mL, 16.4
mmol) in anhydrous THF (25 mL). The reaction was
quenched after 2 h, and the crude was purified by
column chromatography (ethyl ether/petroleum ether
40–60° 1:4) to yield 5 (1.73 g, 92%) as a colourless
syrup. [h]2D5=−6.6 (c 1.2, CH2Cl2). IR (neat): w 1597,
4.7. General procedure for the azide reduction
Triphenylphosphine (393 mg, 1.5 mmol) was added to a
solution of the azide (1 mmol) in anhydrous THF (4.6
ml) and the reaction mixture was stirred until TLC
control showed that the starting material had been
completely consumed. At this point, water (360 mL, 20
mmol) was added and the mixture was stirred for 1 h at
reflux. The solvent was then evaporated at reduced
pressure, and the amine was finally purified by column
chromatography (eluting with CH2Cl2 and then with
CH2Cl2/MeOH 30:1).
1
1490, 1447, 1077, 767, 704 cm−1. H NMR (300 MHz,
CDCl3) l 7.38–7.10 (m, 15H), 5.93 (m, 1H), 5.74 (ddd,
1H, J 17.4, 9.9, 7.2), 5.31 (ddd, 1H, J 18.9, 3.3, 1.8),
5.27 (ddd, 1H, J 17.4, 1.8, 1.2), 5.22 (ddd, 1H, J 9.9,
1.8, 1.2), 5.17 (ddd, 1H, J 10.5, 3.3, 1.2), 4.12 (ddd, 1H,
J 13.0, 5.0, 1.2), 3.98 (ddd, 1H, J 13.0, 5.7, 1.2), 3.94
(m, 1H), 3.27 (dd, 1H, J 9.6, 6.4, 1.2), 3.07 (dd, 1H, J
9.6, 5.1). 13C NMR (74.5 MHz, CDCl3) l in ppm:
144.0, 136.3, 135.0, 128.7, 127.7, 126.9, 117.7, 116.5,
86.5, 79.6, 69.8, 66.6. Anal. calcd for C26H26O2: C,
84.29; H, 7.07. Found: C, 84.34; H, 7.02.
4.8. (S)-1-O-Trityl-but-3-en-1,2-diol 3
In a two-necked flask, the salt (CH3)3S+I− (4.84 g, 23.7
mmol) was dissolved in THF (73.0 mL), and then BuLi
(2.5 M in hexanes, 9.2 mL, 23.0 mmol) was added at
−10°C. The mixture was stirred for 30 min, and then
the epoxide 1 (2.50 g, 7.90 mmol), dissolved in THF
(7.3 mL), was added dropwise. The reaction was slowly
warmed to rt. After 2 h, dimethyl sulfide was removed
with an argon stream, the flask was cooled to 0°C, and
water was added dropwise. The mixture was extracted
with ethyl ether, and the combination of organic phases
was dried over magnesium sulfate and filtered. The
crude obtained after evaporation of the solvent was
purified by column chromatography (ethyl ether/
petroleum ether 40–60°, gradually increasing the polar-
ity from 1:2 to 1:1) to afford pure 3 as a syrup (1.80 g,
69%). [h]2D5=−2.5 (c 1.1, CH2Cl2). IR (neat): w 3430,
4.11. (S)-2-O-Ally1-O-benzyl-but-3-en-1,2-diol 6
The general method for the allylation reaction was
applied, starting from 4 (874 mg, 4.90 mmol), NaH
(60%, 589 mg, 14.7 mmol), allyl bromide (1.30 mL, 15.2
mmol) in anhydrous THF (22 mL). The reaction was
quenched after 1 h, and the crude was purified by
column chromatography (ethyl ether/petroleum ether
40–60° 1:5) to give compound 6 (778 mg, 82%) as a
colourless syrup. [h]D25=+1.1 (c 1.3, CH2Cl2). IR (neat):
1
w 1644, 1453, 1205, 738, 698 cm−1. H NMR (400 MHz,
CDCl3) l 7.25–7.08 (m, 5H), 5.92 (dddd, 1H, J 17.3,
10.3, 6.0, 5.2), 5.76 (ddd, 1H, J 17.5, 10.4, 6.6), 5.30
(ddd, 1H, J 17.5, 1.8, 1.2), 5.29 (ddd, 1H, J 17.3, 3.2,
1.6), 5.26 (ddd, 1H, J 10.4, 1.8, 0.8), 5.17 (ddd, 1H, J
10.3, 3.2, 1.4), 4.61 (d, 1H, J 12.0), 4.56 (d, 1H, J 12.0),
4.27 (ddd, 1H, J 13.4, 5.2, 1.6), 4.00 (m, 1H), 3.94 (dtd,
1H, J 13.4, 6.0, 1.6), 3.55 (dd, 1H, J 10.2, 6.4, 1.6), 3.50
(dd, 1H, J 10.2, 4.4). 13C NMR (100.5 MHz, CDCl3) l
in ppm: 138.2, 135.7, 134.8, 128.3, 127.6, 127.5, 118.2,
116.8, 79.3, 73.3, 72.8, 69.6. Anal. calcd for C22H20O2:
C, 77.03; H, 8.31. Found: C, 77.08; H, 8.67.
1
1596, 1490, 1445, 1075, 768, 740 cm−1. H NMR (300
MHz, CDCl3) l 7.46–7.21 (m, 15H), 5.80 (ddd, 1H, J
17.4, 10.6, 5.7), 5.30 (dt, 1H, J 17.4, 1.8), 5.15 (ddd, 1H,
J 10.6, 1.8, 1.5), 4.27 (m, 1H), 3.21 (dd, 1H, J 9.3, 3.9),
3.11 (dd, 1H, J 9.3, 7.4), 2.46 (bs, 1H). 13C NMR (74.5
MHz, CDCl3) l in ppm: 143.7, 136.9, 128.6, 127.8,
127.1, 116.3, 86.7, 71.9, 67.4. Anal. calcd for C23H22O2:
C, 83.60; H, 6.71. Found: C, 83.91; H, 6.51.
4.9. (S)-2-O-Allyl-1-trityl-but-3-en-1,2-diol
The method for the synthesis of 3 was followed, start-
ing from 2 (864 mg, 5.26 mmol), (CH3)3S+I− (3.22 g,
15.78 mmol), BuLi (6.1 mL, 12.25 mmol) in THF (56.5
mL). The reaction was completed after 3 h 30 min.
After the treatment previously described, column chro-
matography (ethyl ether/petroleum ether 40–60°, gradu-
ally increasing the polarity from 1:4 to 1:1) furnished
alkenol 4 (769 mg, 82%) as a syrup. [h]2D5=−0.4 (c 1.0,
CH2Cl2). IR (neat): w 3435, 1596, 1496, 1443, 1098, 768,
4.12. (S)-2-Trityloxymethyl-2,5-dihydrofuran 7
Starting from diene 5 (1.85 g, 5.40 mmol), ruthenium
catalyst (291 mg, 0.35 mmol) and dichloromethane (a
total of 250 mL), the general procedure for the
metathesis reaction was applied. The reaction was com-
pleted in 4 h, and after purification (hexanes/ethyl
acetate 10:1), compound 7 was isolated in pure form as
a white solid (1.33 g, 78%). Mp=102–109°C. [h]2D5=
−7.8 (c 0.9, CH2Cl2). IR (neat): w 1596, 1490−1446,
1
699 cm−1. H NMR (300 MHz, CDCl3) l 7.35–7.24 (m,
1
5H), 5.83 (ddd, 1H, J 17.5, 10.7, 5.6), 5.35 (dt, 1H, J
17.5, 1.5), 5.19 (dt, 1H, J 10.7, 1.5), 4.56 (m, 2H), 4.34
(m, 1H), 3.53 (dd, 1H, J 9.6, 3.3), 3.37 (dd, 1H, J 9.3,
7.6), 2.63 (bs, 1H). 13C NMR (74.5 MHz, CDCl3) l in
ppm: 137.7, 136.5, 128.4, 127.8, 127.7, 116.4, 73.9, 73.3,
71.4. Anal. calcd for C22H20O2: C, 74.13; H, 7.92.
Found: C, 73.94; H, 8.28.
1092, 761–702 cm−1. H NMR (300 MHz, CDCl3) l
7.48–7.18 (m, 15H), 5.96 (ddd, 1H, J 6.0, 4.0, 1.5), 5.80
(m, 1H), 5.00 (m, 2H), 4.71 (m, 2H), 3.15 (dd, 1H, J
9.3, 5.6), 3.10 (dd, 1H, J 9.3, 4.5). 13C NMR (74.5
MHz, CDCl3) l: 144.0, 128.7, 127.7, 127. 6, 127.4,
126.9, 86.3, 85.4, 75.5, 66.5. Anal. calcd for C24H22O2:
C, 84.18; H, 6.48. Found: C, 83.95; H, 6.17.