6710
K. Sa-ei, J. Montgomery / Tetrahedron 65 (2009) 6707–6711
(316 mg, 2.0 mmol) gave, after column chromatography (2% ether/
hexanes), 352 mg of (S)-tert-butyl 2,2-dimethyl-4-((S,Z)-1-(triiso-
propylsilyloxy)-2-(trimethylsilyl)hept-2-enyl)oxazolidine-3-car-
boxylate (3c) (68%) as a colorless oil as a (>95:5) ratio of
9H), 1.21–1.32 (m, 4H), 1.04–1.17 (m, 21H), 0.84 (t, J¼7.2 Hz, 3H),
13
0.29 (s, 9H); C NMR (100 MHz, C6D6, 75 ꢁC)
d 154.0, 143.5, 139.8,
80.9, 79.9, 73.3, 66.2, 60.0, 32.3, 31.9, 28.6, 22.8, 18.52, 18.50, 13.9,
13.3, 0.42; IR (film) 2945, 1705 cmꢀ1; HRMS ES (m/z): [MþNa]þ
calcd for C27H55NNaO4Si2 536.3567; found 536.3572.
diastereomers. 1H NMR (400 MHz, C6D6, 80 ꢁC)
d
6.57 (t, J¼7.6 Hz,
1H), 5.30 (major rotamer isomer, br s, 0.85H), 5.18 (minor rotamer,
br s, 0.15H), 4.27–4.34 (m, 1H), 4.03 (s, 1H), 3.78 (t, J¼8.4 Hz, 1H),
2.10–2.23 (m, 2H), 1.70 (s, 3H), 1.69 (s, 3H), 1.52 (s, 3H), 1.42 (s, 9H),
4.3.7. (S)-tert-Butyl 4-((S,Z)-1-(triisopropylsilyloxy)-2-
(trimethylsilyl)hexadec-2-enyl)oxazolidine-3-carboxylate (8d)
Following the general procedure, (S)-tert-butyl 4-formyloxazolidine-
3-carboxylate (7) (100 mg, 0.50 mmol), trimethyl(pentadec-1-ynyl)silane
(2d) (168 mg, 0.60 mmol), Ni(COD)2 (14 mg, 0.50 mmol), 1,3-dimesityli-
midazolium chloride (14 mg, 0.10 mmol), t-BuOK (6 mg, 0.50 mmol),
and i-Pr3SiH (158 mg,1.0 mmol) gave, aftercolumn chromatography
(2% ether/hexanes), 249 mg of (S)-tert-butyl 4-((S,Z)-1-(triisopro-
pylsilyloxy)-2-(trimethylsilyl)hept-2-enyl)oxazolidine-3-carboxyl-
ate (8d) (78%) as a colorless oil as a (>95:5) ratio of diastereomers.1H
1.27–1.44 (m, 4H), 1.14–1.22 (m, 21H), 0.87 (t, J¼7.2 Hz, 3H), 0.36 (s,
13
9H); C NMR (100 MHz, C6D6, 80 ꢁC)
d 153.5, 143.8, 140.8, 95.3,
79.6, 74.2, 62.7, 62.2, 32.3, 31.9, 28.6, 27.2, 26.2, 22.8, 18.7, 18.4, 13.9,
13.6, 0.78; IR (film) 2924, 1705 cmꢀ1; HRMS ES (m/z): [MþNa]þ
calcd for C29H59NNaO4Si2 564.3880; found 564.3875.
4.3.4. (S)-tert-Butyl 4-((S,E)-1-(triisopropylsilyloxy)-2-
(trimethylsilyl)but-2-enyl)oxazolidine-3-carboxylate (8a)
Following the general procedure, (S)-tert-butyl 4-formylox-
azolidine-3-carboxylate (7)15 (100 mg, 0.50 mmol), trimethyl-
(prop-1-ynyl)silane (2a) (67 mg, 0.60 mmol), Ni(COD)2 (14 mg,
0.05 mmol), 1,3-dimesitylimidazolium chloride (17 mg, 0.05 mmol),
t-BuOK (6 mg, 0.05 mmol), and i-Pr3SiH (158 mg, 1.0 mmol) gave,
after column chromatography (2% ether/hexanes), 182 mg of (S)-
tert-butyl 4-((S,E)-1-(triisopropylsilyloxy)-2-(trimethylsilyl)but-2-
enyl)oxazolidine-3-carboxylate (8a) (80%) as a colorless oil as
NMR (400 MHz, C6D6, 75 ꢁC)
d
6.23 (t, J¼7.2 Hz, 1H), 5.23 (s, 2H),
4.75 (d, J¼4.0 Hz, 1H), 4.23 (t, J¼7.6 Hz, 1H), 4.03 (t, J¼7.2 Hz, 1H),
3.83 (t, J¼8.0 Hz, 1H), 2.11–2.29 (m, 2H), 1.41 (s, 9H), 1.27–1.38 (m,
22H), 1.12–1.18 (m, 21H), 0.90 (t, J¼7.2 Hz, 3H), 0.30 (s, 9H); 13C
NMR (100 MHz, C6D6, 75 ꢁC)
d 153.5, 143.5, 139.8, 80.9, 79.9, 73.2,
66.2, 60.1, 32.2, 30.2, 30.1, 30.0, 29.9, 29.8, 29.7, 28.6, 23.0, 18.54,
18.48, 14.1, 13.3, 0.44; IR (film) 2925, 1705, 1612 cmꢀ1; HRMS ES
(m/z): [MþNa]þ calcd for C36H73NNaO2Si2 662.4976; found
642.4979.
1
a (>95:5) ratio of diastereomers. H NMR (400 MHz, C6D6, 75 ꢁC)
d
6.62 (qd, J¼7.2, 1.2 Hz, 1H), 5.22 (br s, 1H), 5.18 (s, 1H), 4.75 (d,
J¼4.4 Hz,1H), 4.16 (dd, J¼8.0, 7.2 Hz,1H), 3.99 (td, J¼7.2, 2.4 Hz,1H),
3.75 (t, J¼8.0 Hz, 1H), 1.67 (dd, J¼7.2, 1.2 Hz, 3H), 1.41 (s, 9H), 1.12–
4.4. Synthesis of
(Scheme 3)
D-erythro-sphingosine from compound 3a
1.14 (m, 21H), 0.27 (s, 9H); 13C NMR (100 MHz, C6D6, 75 ꢁC)
d 154.0,
141.2, 137.4, 80.8, 79.9, 73.4, 73.2, 66.2, 60.1, 28.5, 18.44, 18.39, 17.2,
13.29, 13.27, 0.13;IR (film) 2944, 2867, 1705, 1616 cmꢀ1; HRMS
ES (m/z): [MþNa]þ calcd for C24H49NNaO4Si2 494.3098; found
494.3100.
4.4.1. (S)-tert-Butyl 4-((R,E)-1-hydroxybut-2-enyl)-2,2-
dimethyloxazolidine-3-carboxylate (10)
n-Bu4NF (15.0 mL of 1.0 M in THF, 10.0 equiv) was added to
dissolve (S)-tert-butyl 2,2-dimethyl-4-((S,E)-1-(triisopropylsily-
loxy)-2-(trimethylsilyl)but-2-enyl)oxazolidine-3-carboxylate (3a)
(750 mg, 1.5 mmol) at rt. The solution was stirred for 12 h at rt, and
the mixture was quenched with saturated sodium bicarbonate and
extracted with ethyl acetate three times. The combined organic
layers were washed with brine and dried over magnesium sulfate,
filtered, and concentrated in vacuo. The residue was purified via
flash column chromatography (30% ether/hexanes) to afford
369 mg of (S)-tert-butyl 4-((R,E)-1-hydroxybut-2-enyl)-2,2-dimethyl-
oxazolidine-3-carboxylate (10) (91%) as a colorless oil. 1H NMR
4.3.5. (S)-tert-Butyl 4-((S,E)-3-phenyl-1-(triisopropylsilyloxy)-2-
(trimethylsilyl)allyl)oxazolidine-3-carboxylate (8b)
Following the general procedure, (S)-tert-butyl 4-formylox-
azolidine-3-carboxylate (7) (100 mg, 0.50 mmol), 1-phenyl-2-(tri-
methylsilyl)acetylene (2b) (104 mg, 0.60 mmol), Ni(COD)2 (14 mg,
0.05 mmol), 1,3-dimesitylimidazolium chloride (17 mg, 0.05 mmol),
t-BuOK (6 mg, 0.05 mmol), and i-Pr3SiH (158 mg, 1.0 mmol) gave,
after column chromatography (2% ether/hexanes), 213 mg of (S)-
tert-butyl 4-((S,E)-3-phenyl-1-(triisopropylsilyloxy)-2-(trimethyl-
silyl)allyl)oxazolidine-3-carboxylate (8b) (80%) as a light yellow oil
as a (>95:5) ratio of diastereomers. 1H NMR (400 MHz, C6D6, 75 ꢁC)
(400 MHz, C6D6, 75 ꢁC)
d
5.57 (dq, J¼15.2, 6.4 Hz, 1H), 5.42 (dd,
J¼15.2, 6.0 Hz, 1H), 4.21–4.28 (m, 1H), 3.86–3.96 (m, 1H), 3.74–3.82
(m, 1H), 3.64 (dd, J¼8.8, 6.8 Hz, 1H), 3.00 (v. br s, 1H), 1.61 (s, 3H),
1.55 (d, J¼6.4 Hz, 3H), 1.45 (s, 3H), 1.37 (s, 9H); 13C NMR (100 MHz,
d
7.81 (s, 1H), 7.03–7.17 (m, 5H), 5.44 (s, 1H), 5.24 (s, 1H), 4.77 (d,
J¼4.0 Hz, 1H), 4.25 (t, J¼7.6, 1.6 Hz, 1H), 4.16 (dt, J¼1.6, 7.6 Hz, 1H),
C6D6, 75 ꢁC)
d 131.7,126.8, 94.5, 80.0, 73.7, 64.9, 62.7, 28.4, 26.8, 24.4,
3.91 (t, J¼7.6 Hz, 1H), 1.42 (s, 9H), 1.82–1.90 (m, 21H), 0.12 (s, 9H);
17.6; IR (film) 3432, 2923, 1703 cmꢀ1; HRMS ES (m/z): [MþNa]þ
13C NMR (100 MHz, C6D6, 75 ꢁC)
d
154.1, 144.6, 142.1, 140.7, 128.7,
calcd for C14H25NNaO4 294.1681; found 294.1676.
128.2, 127.3, 80.9, 80.1, 73.84, 73.76, 66.1, 60.0, 28.6, 18.6, 18.5, 13.41,
13.43, 0.73; IR (film) 2944, 2867, 1702 cmꢀ1; HRMS ES (m/z):
[MþNa]þ calcd for C29H51NNaO4Si2 556.3254; found 556.3249.
4.4.2. (S)-tert-Butyl 4-((R,E)-1-hydroxyhexadec-2-enyl)-2,2-
dimethyloxazolidine-3-carboxylate (11)
Dichloromethane was added to dissolved (S)-tert-butyl 4-((R,E)-
1-hydroxybut-2-enyl)-2,2-dimethyloxazolidine-3-carboxylate (10)
(85 mg, 0.40 mmol) and pentadec-1-ene (170 mg, 0.80 mmol).
Second generation Grubbs catalyst (33 mg, 0.04 mmol) was added
to the solution and the reaction mixture was heated at reflux for
2 h. Additional pentadec-1-ene (170 mg, 0.80 mmol) and second
generation Grubbs catalyst (33 mg, 0.04 mmol) were then added.
After another 4 h, more second generation Grubbs catalyst (33 mg,
0.04 mmol) was added. The mixture was then concentrated, and
the residue was purified via flash chromatography (30% ether/
hexanes) to provide 144 mg of (S)-tert-butyl 4-((R,E)-1-hydroxy-
hexadec-2-enyl)-2,2-dimethyloxazolidine-3-carboxylate (11) (82%)
as a colorless oil. 1H NMR data (400 MHz, C6D6, 60 ꢁC) were iden-
tical to that previously reported.10a
4.3.6. (S)-tert-Butyl 4-((S,Z)-1-(triisopropylsilyloxy)-2-
(trimethylsilyl)hept-2-enyl)oxazolidine-3-carboxylate (8c)
Following the general procedure, (S)-tert-butyl 4-formylox-
azolidine-3-carboxylate (7) (100 mg, 0.50 mmol), hex-1-ynyltri-
methylsilane (2c) (92 mg, 0.60 mmol), Ni(COD)2 (14 mg, 0.50 mmol),
1,3-dimesitylimidazolium chloride (14 mg, 0.10 mmol), t-BuOK
(6 mg, 0.50 mmol), and i-Pr3SiH (158 mg, 1.0 mmol) gave, after
column chromatography (2% ether/hexanes), 200 mg of (S)-tert-
butyl 4-((S,Z)-1-(triisopropylsilyloxy)-2-(trimethylsilyl)hept-2-enyl)-
oxazolidine-3-carboxylate (8c) (78%) as a colorless oil as a (>95:5)
ratio of diastereomers. 1H NMR (400 MHz, C6D6)
1H), 5.25 (br s, 2H), 4.75 (d, J¼4.0 Hz, 1H), 4.21 (t, J¼7.6 Hz, 1H),
4.00–4.10 (m, 1H), 3.84 (t, J¼7.6 Hz, 1H), 2.00–2.18 (m, 2H), 1.39 (s,
d
6.57 (t, J¼7.2 Hz,