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I. Izzo et al. / Tetrahedron: Asymmetry 16(2005) 1503–1511
eliminate Ac2O. The crude was dissolved in diethyl ether
and filtered on a short plug of Celite. The Et2O was evap-
orated in vacuum and the crude purified by flash chroma-
tography on silica gel (hexane–ether 8:2–65:35) to afford
a colourless oil 24 (143 mg, 64%). Sulfide 25 (10–30%)
was isolated as the secondary product during the various
was refluxed overnight at 120–130 ꢁC. Toluene was
added many times and evaporated to eliminate Ac2O.
The crude was dissolved in diethyl ether and filtered
on a short plug of Celite. Et2O was evaporated in vac-
uum and the crude purified by flash chromatography
on silica gel (hexane–ether 8:2–65:35) affording a color-
less oil (74 mg, 82%).
1
attempts. H NMR (200 MHz, CDCl3): d 7.36 (d, 2H,
J = 8.0Hz, C 6H4, I dia), 7.32 (d, 2H, J = 8.0Hz, C 6H4,
II dia), 7.11 (d, 4H, J = 8.0Hz, C 6H4, I and II dia), 6.4
(d, 1H, J = 3 Hz, I dia), 6.12 (d, 1H, J = 7 Hz, II dia),
5.80(m, 2H, I and II dia), 5.3 (m, 2H, I and II dia),
5.02 (m, 4H, I and II dia), 4.88 (dd, 1H, J = 7 and
3 Hz, I dia), 3.86 (dd, 1H, J = 7 and 1 Hz, II dia), 2.31
(s, 6H), 2.05 (s, 3H), 2.01 (s, 6H), 1.99 (s, 3H, II dia),
2.43–1.99 (m, 4H), 0.87 (s, 9H, s, I dia), 0.85 (s, 9H, II
dia), 0.07, 0.06, 0.05 (s, 12H, I and II dia). 13C NMR
(CDCl3): d 169.7, 169.5, 168.5, 138.4, 137.8, 134.5,
134.2, 132.6, 129.5, 129, 127.7, 117.7, 117.4, 97.1, 96.3,
82.3, 81.0, 72.8, 72.3, 38.2, 37.6, 25.8, 21.1, 18.2, À4.1,
1
Rf (two diastereoisomers, half point): 0.52. H NMR
(300 MHz, CDCl3): d 7.38 (d, 2H, J = 8.0Hz, C 6H4, I
dia), 7.33 (d, 2H, J = 8.0Hz, C 6H4, II dia), 7.09 (d,
4H, J = 8.0Hz, I and II dia), 6.34 (d, 1H, J = 4.2 Hz, I
dia), 6.32 (d, 1H, J = 2.7 Hz, II dia), 5.80(m, 2H, I
and II dia), 5.02 (m, 4H, I and II dia), 4.85 (d, 4H,
J = 7.0Hz superimposed of I and II dia), 3.98–3.52
(m, 12H, I and II dia), 3.37 (s, 3H, I dia), 3.36 (s, 3H,
II dia), 2.31 (s, 9H), 2.01 (s, 3H, I dia), 1.99 (s, 3H, II
dia), 2.43–1.99 (m, 4H), 0.88 (s, 9H, I dia), 0.86 (s,
9H, II dia), 0.07, 0.06, 0.05 (s, 12H, I and II dia). 13C
NMR (75 MHz, CDCl3): d 169.3, 169.1, 138.6, 138.0,
134.7, 134.4, 132.8, 129.7, 129.2, 127.9, 117.7, 117.4,
97.1, 96.5, 82.3, 81.0, 80.5, 80.1, 72.8, 72.3, 71.6, 67.8,
67.4, 58.9, 38.2, 37.6, 25.8, 21.1, 17.9, À4.4, À4.7.
1
À4.5. H NMR (200 MHz, CDCl3) of sulfide 25: d 7.29
(d, 2H, J = 7 Hz), 7.12 (d, 2H, J = 7 Hz), 5.72 (m, 1H),
5.05 (m, 3H), 3.85 (m, 1H), 3.02 (AB of an ABX system,
2H, JAX = 3 Hz, JBX = 7 Hz, JAB = 13 Hz, Dm = 45 Hz),
2.2–3 (m, 2H), 2.02 (s, 3H), 0.88 (s, 9H), 0.1 (2s, 6H).
13C NMR (50MHz, CDCl 3) of sulfide 25: d 168.5,
136.2, 127.4, 129.9, 124.6, 117.6, 75.2, 72.5, 36.8, 33.3,
25.7, 20.9, 18.6, À0.4, À0.43.
4.16. (3R,2R)-1-Hydroxy-2-tert-butyl-dimethylsilyloxy-
3-methoxyethoxymethyloxy-5-hexene 31
To a solution of 30 (0.248 g, 0.496 mmol) in dry Et2O
(12 mL), LiBH4 (43 mg, 1.99 mmol) was added. The
solution was stirred at room temperature for 3 h. The
solution was cooled to 0 ꢁC, diluted with Et2O (10mL)
and HCl (1 M, 10mL) added slowly. The aqueous phase
was extracted twice with CH2Cl2 (20mL) and once with
AcOEt (20mL). The organic layer was washed with
brine, dried over MgSO4 and concentrated in vacuum.
The crude was purified by flash chromatography (hex-
ane–ethyl acetate 4:1–3:2) affording a white amorphous
crystals (118 mg, 71%). Rf: (hexane–ethyl acetate 3:2)
4.14. (3R,2S,RS)-1-(p-Tolylsulfinyl)-2-tert-butyl-dimeth-
ylsilyloxy-3-methoxyethoxymethyloxy-5-hexene 29
To a suspension of KH (9.5 mg, 0.316 mmol) in dry
THF (1 mL) cooled to À78 ꢁC was added dropwise a
solution of alcohol 23 (58 mg, 0.158 mmol) in dry
THF (1.5 mL). The suspension was stirred for 30min
at À78 ꢁC and MEMCl (36 lL, 0.316 mmol) added.
The solution was stirred at À78 ꢁC for 15 min and at
rt for 1 h 30min. Saturated aqueous NH 4Cl (5 mL)
was added and the mixture extracted twice times with
AcOEt (10mL · 2) and once with CH2Cl2 (10mL).
The combined organic layers were washed with brine,
dried over MgSO4 and evaporated under reduced pres-
sure. The crude was purified by flash chromatography
on silica gel (hexane–ether 1:1 to ether) to afford a col-
ourless oil (53 mg, 77%). Rf: (hexane–ethyl acetate 3:2)
0.4. 1H NMR (300 MHz, CDCl3): d 7.41 ((AB)2 system,
4H, JAB = 8.2 Hz, Dm = 40Hz), 5.75 (m, 1H), 4.99 (m,
2H), 4.91 (d, 1H, J = 7.0Hz), 4.89 (d, 1H, J = 7.0Hz),
4.13 (m, 1H), 3.97 (m, 1H), 3.78 (m, 2H), 3.58 (m,
2H), 3.39 (s, 3H), 2.87 (AB fragment of an ABX system,
2H, JAX = 1.7 Hz, JBX = 10.6 Hz, JAB = 13.1 Hz,
Dm = 45 Hz), 2.40(s, 3H), 1.98 (m, 2H), 0.85 (s, 9H),
0.08 (s, 3H), 0.03 (s, 3H). 13C NMR (CDCl3): d 142.0,
141.4, 135.6, 130.0, 123.9, 117.1, 96.4, 75.2, 72.2, 71.8,
67.6, 59.3, 59.1, 36.1, 25.9, 21.4, 18.0, À4.33, À4.51.
1
0.4; H NMR (200 MHz, CDCl3): d 5.77 (m, 1H), 5.02
(br d, 1H), 5.01 (br d, 1H), 4.81 (d, 1H, J = 7.0Hz),
4.71 (d, 1H, J = 7.0Hz,), 3.86–3.46 (m, 6H), 3.35 (s,
3H), 2.34 (m, 1H), 2.10 (m, 1H), 0.85 (s, 9H), 0.03 (s,
3H), 0.02 (s, 3H). 13C NMR (50MHz, CDCl 3): d
135.0, 117.0, 96.5, 84.0, 72.6, 71.5, 67.3, 62.2, 58.8,
37.2, 25.7, 17.9, À4.6, À4.7. [a]D = +36 (c 2.2, CHCl3).
References
´
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Hanquet, G.; Solladie, G.; Izzo, I.; Crumbie, R. Tetrahe-
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[a]D = +140( c 2.0CHCl ).
3
4.15. (3R,2S)-1-(p-Tolylsulfenyl)-1-(acetoxy)-2-tert-
butyl-dimethylsilyloxy-3-methoxyethoxymethyl-5-
hexene 30
To a solution of 29 (84 mg, 0.18 mmol) in Ac2O (4 mL)
was added AcONa (177 mg, 2.16 mmol). The mixture
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657–665.